We perform 3D hydrodynamics simulations of an equal-mass quasi-circular live $10^6~{\rm M}_\odot$ massive black hole binary (MBHB) embedded in a prograde, locally isothermal circumbinary disk (CBD) with $0.1$ aspect ratio. The binary evolution is driven by the gaseous torques and its dynamics is described with $2.5$ post-Newtonian corrections. This approach allows us to track the influence of the CBD on a gravitational-wave (GW) driven MBHB inspiral from $55$ to $46$ Schwarzschild radii, i.e., at its early evolution in the LISA band at redshift $z\sim1$. For the first time for the $0.1$ aspect ratio disk, we report the measurement of gravitational and accretion torques with and without concurrent GW emission. We also report how the morphology of the accretion time series onto the MBHB modestly alters when GW emission is the dominant binary evolutionary mechanism. Lastly, we find that the gas-induced orbital phase-shift is $0.12$ rad over $600$ orbital cycles, which LISA should detect at $z=1$. Our results have implications for multi-messenger astronomy, since observation of accretion rate modulation by LSST/Roman surveys and phase-shift by LISA will provide crucial information on the complex environment surrounding MBHBs.

The period distribution of hot gaseous exoplanets depends strongly on mass. Clustering between the orbital periods of $\sim$3 to $\sim$5-6 days is seen for sub-Saturns ("Neptune ridge") and Jovians ("hot Jupiter pile-up"), contrasting with a sharp deficit interior to 3 days for sub-Saturns, not seen for Jovians ("Neptune desert"). During high-eccentricity migration, tidally-excited fundamental-modes (f-modes) act as a reservoir for orbital energy, and can take gaseous planets formed beyond several AU and place them at short separations. However, how f-modes relinquish their energy into the planet interior is unknown. Here, we show how f-modes can not only circularize orbits -- causing clustering near the Neptune ridge and hot-Jupiter pile-up -- but can also shock and unbind mass, leaving sub-Saturn cores in the Neptune desert. Our hydrodynamical simulations demonstrate that close approaches tidally excite f-modes, whose super-sonic velocities shock gaseous envelopes. Atmospheres cool by radiative diffusion or winds when shocks penetrate shallow versus deep depths. Planetary structural and orbital evolution is followed over many periastron passages using an iterative map: shocks that diffusively cool circularize and bunch orbits near the hot Jupiter pile-up and Neptune ridge, while shocks that drive outflows unbind envelopes and place gas giant cores in the Neptune desert. Sub-Saturns that dwell in the desert are predicted to arrive with large spin-orbit misalignments after producing luminous flares.

Galaxy formation models predict that galaxies grow inside-out, becoming larger over time. While observations broadly support this paradigm, the nature and timescales of this growth remain poorly constrained. We report the discovery of an extremely faint and young (~600 Myr) stellar component in the outer regions of the nearby galaxy Messier 74 (M74). Using deep optical imaging from the TST telescope at the Teide Observatory, reaching surface brightness limits of ~30-31.5 mag arcsec^-2 in the g, r and i bands, we detect stellar emission extending well beyond the previously known disc radius of ~14 kpc. This newly identified component reaches galactocentric distances of ~30 kpc, effectively doubling the known size of the stellar disc and matching the extent of the HI disc. The revised size of M74 places it in the upper envelope of the mass-size relations. The young age of the outer stellar population suggests a recent episode of disc growth, potentially occurring on timescales shorter than ~1 Gyr. We discuss a possible scenario in which a past flyby interaction with UGC 1176 may have triggered this extended star formation. Further studies of galaxies with similar deep imaging will be key to determining whether such rapid outer disc growth is common or exceptional.

Gravity models in which the dark energy equation of state crosses $w=-1$, also known as the phantom divide, have received extensive interest due to recent analyses favouring this behaviour. We introduce a new subclass of Horndeski scalar-tensor models capable of generating phantom crossing, whilst remaining minimally coupled to matter: the Asymptotic Cubic Galileon (ACG) models. We show that ACG models can jointly fit the expansion history inferred from observations of the Planck cosmic microwave background, baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument, and distance-ladder supernovae measurements from the Dark Energy Survey. We then demonstrate that perturbative observables, including the galaxy-ISW cross-correlation and void force profile, provide powerful constraints that confine viable and testable ACG models to a well-defined region of the broader Horndeski landscape. Model comparison metrics, including $\chi^{2}$ and Bayesian evidence, favour both ACG and $w_{0}w_{a}$CDM models over $\Lambda$CDM, with ACG providing a fit of comparable quality to $w_{0}w_{a}$CDM. Crucially, ACG models ground the observationally preferred $w_{0}w_{a}$CDM behaviour in a robust Lagrangian formulation. This enables interpretation beyond mere phenomenological fits, and motivates further tests of these models on nonlinear scales.

Within the highly successful $\Lambda$CDM paradigm established with cosmic microwave background (CMB) anisotropy measurements, the optical depth through reionization $\tau$ is the most uncertain due both to the difficulty in measuring large-angle polarization and the assumptions made in their interpretation. Currently, for the Planck primary data in the flat $\Lambda$CDM cosmology with slow-roll inflation and standard reionization, the one-sided 95% upper limit for $\tau$ is $\tau_{\rm max}=0.0696$. Yet when all current CMB measurements excluding large-angle polarization are combined with baryon acoustic oscillation (BAO) measurements, the one-sided 95% lower limit is an incompatible $\tau_{\rm min}=0.074$. If the long-standing low-power feature of the temperature measurements is interpreted as physically originating from inflation then $\tau$ inferred from large-angle polarization becomes larger. Marginalizing over templates of the low-power feature based on the generalized slow-roll formalism of inflation raises the Planck maximum to a more compatible $\tau_{\rm max}=0.075$ which further increases to $\tau_{\rm max} = 0.082$ with the inclusion of all CMB+BAO data. This marginalization does not assess the statistical significance of the low-power feature itself; rather, it shows that allowing a higher $\tau$ is a consequence of interpreting the anomaly as a physical feature instead of a statistical fluctuation.

We investigate the role of obscured active galactic nuclei (AGN) in recently quenched post-starburst galaxies (PSBs), using a sample of 65 photometrically selected PSBs in the PRIMER-UDS field at $1 < z < 2$. Combining JWST/MIRI 7.7 $\mu$m and 18 $\mu$m (F770W and F1800W) imaging with eight NIRCam and three HST/ACS bands, we probe hot dust emission to test for hidden AGN or dust-enshrouded star formation. We find strong differences between the low- and high-mass PSBs. Most high-mass PSBs ($ > 10^{10}\textrm{M}_\odot$) show no excess infrared emission (consistent with the quiescent population), indicating little or no dust-obscured activity, while low-mass PSBs display enhanced emission at 18 $\mu$m, which we attribute to residual star formation. AGN template modelling indicates that the absence of mid-IR excess in massive PSBs limits any dust-enshrouded AGN to Eddington ratios of $ < 1\%$. In addition, we show that the F770W--F1800W colour alone is a highly effective diagnostic for separating passive and star-forming galaxies, particularly at high stellar masses. Overall, our results provide further evidence for distinct quenching pathways within the PSB population, and confirm that massive PSBs show no evidence for excess AGN activity relative to older passive galaxies.

Strong gravitational lensing combined with JWST's spatio-spectral resolution enables resolved studies of star-forming regions in $z\sim$ 2-4 galaxies, but identifying and characterizing such regions in lensed integral-field and multi-band data remains a manual, observer-dependent process. We present $\texttt{SUMAC}$ (Software for the Uniform Manifold Approximation of Clumps), an unsupervised learning pipeline that segments JWST imaging and spectroscopy at the "spaxel" level by combining $\texttt{UMAP}$-based manifold embedding with $\texttt{HDBSCAN}$ density clustering applied to spectral energy distributions/spectra. We demonstrate the pipeline on JWST/NIRSpec PRISM IFS observations of the lensed galaxy SGAS111020.0+645950.8 at $z = 2.481$, recovering six physically distinct stellar/nebular populations. The cluster median SEDs separate cleanly on the presence and strength of H$\beta$+[OIII], H$\alpha$+[NII], $\beta_{NUV}$ slope, Balmer break strength, and the Balmer decrement, with bluer clusters tracing unobscured star-forming regions and progressively redder clusters tracing dusty star-forming regions.

Stellar obliquities provide a fossil record of hot Jupiter (HJ) migration. An emerging observational trend in single-star systems is that strongly misaligned HJs are largely confined to short orbital periods, while longer-period HJs are preferentially aligned. This pattern cannot be explained by tidal dissipation in the star and may instead preserve clues to the migration pathway. We show that secular high-eccentricity migration driven by a distant planetary companion naturally produces such an obliquity--period correlation. In our simulations, the shortest-period HJs tend to be produced by the von Zeipel--Lidov--Kozai mechanism driven by highly inclined companions, which results in a broad range of final stellar obliquities. The longest-period HJs, on the other hand, are produced over longer timescales by coplanar high-eccentricity migration, which preserves low obliquities. The transition between these two limits is not abrupt, with intermediate-period HJs displaying a moderate range of obliquities. According to this interpretation, we predict that the shortest-period HJs should have distant planetary companions with broadly distributed mutual inclinations, whereas the companions of longer-period HJs should reside in nearly coplanar orbits. Upcoming Gaia astrometric constraints will provide a key test of this picture.

Strong gravitational lensing by galaxy clusters combined with the resolution of JWST enables studies of star formation on ~10-100 pc scales in galaxies at z~2-4. As part of the LEnsing and Galaxy Growth: Observing Substructures survey (LEGGOS), we present an updated strong lensing model of the galaxy cluster SDSSJ1110+6459 (z=0.659), which lenses the clumpy star-forming galaxy SGASJ111020.0+645950.8 at z=2.481 into a highly magnified giant arc. Using JWST NIRCam imaging, NIRSpec spectroscopy, and archival HST data, we confirm and refine the identification of four multiply imaged background sources, including one newly identified system, and map over 20 luminous regions between each image of the primary arc. Spectroscopy confirms that several previously ambiguous edge "clumps" belong to the main arc at z=2.481. Despite the limited number of strongly lensed sources in the field, the resulting lens model has high precision, owing to the high density of JWST-resolved clump constraints that tightly probe the lensing potential near the giant arc. The model yields a projected lens mass of $M(<250~\mathrm{kpc}) = 1.21^{+0.09}_{-0.04} \times 10^{14}~M_\odot$, an Einstein radius of $\theta_\mathrm{E} = 10.8^{+0.3}_{-0.4}~\mathrm{arcsec}$, and a total effective magnification of $\mu_\mathrm{tot}=24.2^{+3.4}_{-1.2}$ for the giant arc. Across the arc, individual clump magnifications span $\mu_\mathrm{clump}\sim4-19$, with fractional magnification uncertainties of $\sigma_\mu/|\mu_{\rm best}|\sim0.03-0.09$. We report a $\sim2-8\times$ improvement in magnification precision over previous models. Ongoing and future analyses of this arc will enable robust measurements of star-forming structure, building on the lensing foundation established here for LEGGOS studies of galaxy growth and feedback during cosmic noon.

We present the first cosmological model for the lifecycle and luminous properties of PAHs in galaxies as they evolve from z=6-->0. We model 40 zoom-in galaxies, coupled with an on-the-fly model for the evolution of dust grains in the ISM. We assume that PAHs are ultrasmall (a < 13 Angstrom) carbonaceous dust grains, and couple this model with single-photon excitation calculations to compute the emergent mid-infrared spectra. (1) If we assume that dust is large upon formation, then PAHs are naturally able to form in situ in the ISM via grain-grain shattering. Interstellar collision velocities increase in low density, diffuse gas in our model; as galaxies evolve, the increase in fractional mass of diffuse gas drives an increase in grain-grain collision velocities and a corresponding rise in the PAH mass fraction (qPAH) from ~5 x 10^{-4} at z~4 to ~10^{-2} at z~0. (2) Increased PAH production in the diffuse ISM results in an inverse relationship between qPAH and the molecular gas fraction. (3) The PAH light-to-mass ratio scales linearly with the radiation field intensity (LPAH/MPAH ~ G_0) but anti-correlates with qPAH, because high-Sigma_SFR galaxies have a denser ISM that suppresses shattering. This means the physical qPAH and observed LPAH/LFIR do not evolve in lockstep. (4) The PAH-metallicity relationship (PZR) arises naturally in this framework: galaxies enrich and grow their diffuse ISM fraction simultaneously, linking rising metallicity to rising qPAH. Our models represent the first to reproduce the PZR observed across z=0-2. (5) The LPAH-SFR and LPAH-M_mol relations emerge from two effects: more massive galaxies have larger PAH reservoirs, and higher-SFR galaxies excite their PAHs more efficiently per unit mass. Taken together, these results suggest that grain-grain shattering in the diffuse ISM is the main driver behind the evolution of cosmic PAH abundances.

Dual nuclei systems are galaxy merger remnants or closely merging galaxies that have two distinct stellar cores separated by ~ 10pc to 10kpc. They are important laboratories for probing the co-evolution of stellar populations, galaxy dynamics, and central black holes during the hierarchical assembly of galaxies. In this study, we present a spectroscopic analysis of a sample of dual nuclei from the GOTHIC survey, using the penalized pixel-fitting (pPXF) code. The sample consists of star forming nuclei pairs, dual active galactic nuclei (DAGN) and mixed pairs. Using the SDSS spectra, we extracted stellar kinematics, emission line fluxes, the star formation history, metallicity of the nuclei, and derived important properties such as the supermassive black hole (SMBH) masses, accretion rates and SMBH ratios. We compared different properties of the nuclei in the dual systems, such as stellar velocity dispersion, stellar masses, black hole masses, age and metallicity. Our results show that the SMBH masses are higher for BHs in galaxy mergers compared to single nuclei for a given stellar mass, thus revealing that SMBHs grow during the galaxy merging process and not only due to the merger of SMBHs. Our study provides new observational constraints on the dynamical and evolutionary states of dual-nuclei systems, offering a deeper understanding of the role these systems play in galaxy evolution and central black hole growth.

The Wide-field Spectroscopic Telescope (WST) is a concept for a dedicated 12-m spectroscopic survey facility designed to address some of the most important questions in astrophysics in the 2040s. The WST will provide unprecedented spectroscopic survey capabilities by operating simultaneously over a 2-degree diameter field of view with 54 low-resolution spectrographs fed by 30,000 fibres, 8-16 high-resolution spectrographs fed by 2,000 fibres, and a large panoramic low-resolution integral-field spectrograph. Supported by Horizon Europe, the concept study has refined the science cases, facility architecture, operations model, sustainability strategy, and technology roadmap. The resulting reference design demonstrates that the WST is both scientifically transformative and technically feasible, while identifying the developments required to mitigate the remaining risks. The WST is designed as an ESO flagship facility for the post-ELT construction era and a key spectroscopic complement to the major imaging, time-domain, and multi-messenger facilities of the coming decades.

We present a LensMC lensing analysis of Euclid Quick Release 1 images that were made available in March 2025. We measured shapes, positions, weights, and other morphological parameters of galaxies with a surface number density of $26\;\text{arcmin}^{-2}$ for $I_{\scriptscriptstyle\rm E}<24.5$, achieving 75 arcmin$^{-2}$ for $I_{\scriptscriptstyle\rm E}<27$, in 63 deg$^2$ of Euclid VIS images. This is the first shear measurement catalogue produced with \lensmc in anticipation of the Euclid Data Release 1. To within the scope of this work and availability of survey volume, we found no spatial dependency in the additive biases. However, we developed an empirical bias correction based jointly on galaxy sizes and magnitudes, which was applied to the measurement of the lensing signal over the whole area. In order to validate the quality of our measurements, we calculated two-point statistics and cluster profile measurements, and cross-checked results with external cluster catalogues from WISE and the Dark Energy Survey. Additionally, by stacking shear profiles of random clusters we found that the low-redshift, large radii bins may be still contaminated by residual systematic effects. Thanks to Euclid image resolution and depth and overall good control of systematic errors, we are able to constrain the lensing profiles of clusters with masses of $10^{14}M_\odot$ out to $z\approx2$ over nearly 10 Gyr of evolution history.

Astrophysical simulations frequently address multi-scale, multi-physics problems through subsystem decomposition, problem-tailored integration schemes, and coupling on fixed manually set timescales. Here we introduce ReLaTS, a reinforcement learning framework that dynamically selects the coupling time step to optimize the trade-off between accuracy and computational cost. We validate ReLaTS on star clusters containing a planetary system, and test the method by varying the number of stars $N_\star$ in the cluster and the number of planets ($N_{\rm planet}$) orbiting one of them. The method finds the optimal coupling time step that balances speed and accuracy without requiring expert knowledge. In addition, the trained network operates independently of the coupled \textit{N}-body algorithms, displaying stable performance across a range of setups. We observe that the method is less reliable for cases with infinitesimal masses, as their contribution to the total energy is negligible compared to that of the massive bodies, and the network is not capable of recognizing potential errors generated while integrating them. For long-time integration of large $N$ systems, the error accumulates. The reinforcement learning algorithm, however, manages to keep the energy error below a pre-set threshold. This approach substantially reduces energy errors relative to fixed-time step baselines without substantial additional computational overhead. Once trained, ReLaTS requires no expert tuning and generalizes across diverse astrophysical domains, enabling adaptive multi-scale simulations.

We present the results from an extensive broad-band (radio to X-rays) observing campaign of the engine-driven Type Ib SN 2012au in the first 13 years of evolution. The early-time (${\delta}t\leq{190}$ d) radio and X-ray evolution is well-described by conventional models of a forward shock interacting with a wind-like circumstellar medium ($\rho_{\rm{CSM}}\propto{r}^{-2}$). However, starting at $\delta{t}\approx{6.7}$ yr, we detect a significant radio re-brightening. This late-time emission is dominated by a luminous component characterized by a broad and rapidly evolving spectral peak and a shallow optically thin spectral slope, $F_{\nu}\propto{\nu}^{-0.31\pm0.02}$. These properties imply a compact emitting region ($R\lesssim{10}^{16}$ cm) expanding at a remarkably slow velocity ($\lesssim{500}$ km/s) into a high-density environment ($\geq{10}^4 \rm{cm}^{-3}$), accompanied by a hard electron power-law index $p\approx{1.6}$. No soft or hard X-ray emission is detected at any epoch, indicating that high-energy radiation is either strongly absorbed or intrinsically absent. In the context of aspherical shock-CSM interaction models, these observations imply extreme properties of the CSM (geometry, density, total mass) that lack clear astrophysical motivation. Instead, we show that the emergence of radiation from a newborn Pulsar Wind Nebula (PWN) naturally explains the radio spectral evolution and high-energy limits, where the emission is governed by the adiabatic expansion of a relic pair plasma. We conclude that SN 2012au represents the most compelling candidate for a young, newborn PWN discovered to date, a scenario that can be directly tested with pending Very Long Baseline Interferometry (VLBI) observations.

Directly imaging and characterizing exoplanets requires extreme adaptive optics (XAO), which achieves exquisite wavefront correction over a small (<5") field of view. Temporal errors, where the wavefront evolves faster than the lag between wavefront sensing and control, are often a leading term in the error budget for these XAO systems. Predictive control mitigates temporal errors by predicting where the wavefront will be by the time the system correction is applied. In particular, empirical orthogonal functions (EOF) learn linear correlations in a wavefront using previous states in the wavefront sensor history. We present on-sky results of a new implementation of EOF built directly into the Keck-II real time controller. On-sky engineering tests at Keck Observatory of the predictive controller show a 20% performance improvement over a classic integrator according to wavefront residuals from the Shack-Hartmann Wavefront Sensor (SHWFS). Parameter optimization studies show that there is a clear improvement based on varying predictive filter hyper-parameters, but that within a reasonable regime, varying filter parameters does not degrade performance to notably worse than an integrator. NIRC2 imaging through the Brackett Gamma=2190nm filter shows comparable performance between an integrator and predictor, both comparing Strehl Ratio (SR) and coronagraph-free contrast. We also explore power in principal components, and find a modest improvement (on the order of 3% less area under the curve of component strength) from the predictor over the integrator. This work not only improves current observing for the Keck community, but also acts as a pathfinder for predictive control methods with extremely large telescopes.

We present first results from the JWST LEGGOS Survey (LEnsing and Galaxy Growth: Observing Substructures), aimed at studying the physics of clumpy star formation and quenching in eight lensed galaxies at $z\sim2$--4. LEGGOS combines multiple Cycle 2 JWST GO programs (GO 4125, GO 3843) and Cycle 1 archival data, and utilizes strong gravitational lensing with NIRCam imaging and NIRSpec integral-field spectroscopy. LEGGOS targets UV-bright, highly magnified systems to resolve $\sim$10--200 pc regions in both rest-frame optical continuum and nebular emission. This overview paper describes the survey design, data reduction and calibration strategy, and science-quality data products, and highlights early examples demonstrating how spectroscopy breaks key degeneracies inherent to photometry-only clump studies, including identifying recent quenching in previously-thought UV star forming galaxies. We introduce a uniform analysis framework that jointly models lensing reconstruction, multi-band photometry, and integral field spectroscopy to disentangle multiple stellar populations within individual clumps and their surrounding diffuse regions. Using maps of Balmer recombination lines and key emission line diagnostic ratios, we connect star formation histories, dust attenuation, and nebular conditions on sub-kpc scales -- LEGGOS galaxies range from uniform metallicities across the whole galaxy, to having higher clump metallicities and harder ionization conditions relative to diffuse regions. The full survey dataset, with simultaneous flux and morphology constraints on clumpy source-plane regions, and a flexible spectrophotometric SPS modeling approach, provides a direct bridge between parsec-scale star formation physics and galaxy assembly at and beyond cosmic noon, offering a robust and efficient means of resolving star formation in the first galaxies.

Solar type II radio bursts are widely regarded as signatures of shock waves propagating in the solar corona and are of particular importance for understanding shock-driven particle acceleration processes. Type II radio bursts often exhibit complex multi-lane and split-band features. The detailed spectral, temporal, and spatial structures carry key information about the shock properties and evolution. However, the physical origin of the multi-lane and split-band features remains unclear, largely due to a lack of spatially resolved data and understanding of the concurrent shock morphology and its magnetic-field context. In this work, we combine radio imaging spectroscopy of a multi-lane, split-band type II burst event with a three-dimensional global magnetohydrodynamic simulation of the associated coronal mass ejection-driven shock using the Alfvén Wave Solar atmosphere Model-Realtime. In this event, the burst intensity evolves from fundamental-emission dominated to harmonic-emission dominated. Meanwhile, the preferential emission source region moves from the Earth-facing side to the limb or far side, coinciding with quasi-perpendicular shock regions with enhanced Mach numbers. The observed spatial offset between the fundamental and harmonic sources is generally aligned with the projected shock-surface magnetic field from the simulation, consistent with anisotropic scattering in a magnetized turbulent plasma. These results establish a physical connection between type II radio sources and coronal shock magnetic geometry, providing new insight into the origin of the multi-lane features and their diagnostics of coronal shocks.

Feedback from massive stars in the form of radiation and winds impacts the associated host molecular cloud. Feedback can disperse cloud material and lead to the destruction of the cloud. Recent observations of the ionized carbon CII 158 micron line in high-mass star-forming regions have demonstrated that this line is an excellent tracer of the gas dynamics in such environments. Expanding CII shells have been detected, along with high-velocity gas escaping the natal cloud through low-density channels. Motivated by these results, we conducted a systematic analysis of spectrally resolved CII maps obtained with SOFIA towards ten high-mass star-forming regions hosting at least one O-type star. Across all regions, we identify high-velocity CII line wings with velocities that exceed the cloud escape velocity, indicating that this gas is not gravitationally confined. We show that the high-velocity gas exhibits a complex velocity structure and cannot be attributed solely to a single, coherent expanding CII bubble. The amount of material in these erosion flows depends on the evolutionary stage of the molecular cloud and its associated HII region. Once the initial bubble around the cluster ruptures, typically after 0.1 Myr, gas is expelled from the cloud. The resulting cloud erosion timescales based on these directly observed mass ejection rates typically vary between 2 and 10 Myr after the formation of the first O stars, similar to other indirect measures of molecular cloud life times. These results suggest that stellar feedback is able to remove enough molecular gas to terminate the star formation in the host cloud.

Since the Fermi satellite's identification of a candidate $\gamma$-ray burst (GRB) temporally coincident with GW150914, several tentative, and often debated, associations between electromagnetic (EM) transients and gravitational-wave (GW) signals from binary black hole (BBH) mergers have been reported. One such event, S241125n (later confirmed as GW241125_010116), was identified during the fourth observing run (O4) of Advanced LIGO and found to be spatially (within large GW localization uncertainty) and temporally coincident with a subthreshold GRB detected by the Swift Burst Alert Telescope Gamma-ray Urgent Archiver for Novel Opportunities (BAT-GUANO). Here, we present results from a radio follow-up campaign targeting the BAT-GUANO localization region, carried out with the Karl G. Jansky Very Large Array (VLA). We also re-analyze Swift/XRT observations of the field, and combine these results with optical upper limits. Our analysis constrains the isotropic kinetic energy of a putative relativistic jet launched in the BBH merger to $\lesssim 3 \times 10^{50}$ erg for $n_{ISM} = 1.0 cm^{-3}$. We also discuss both the challenges and the diagnostic power of radio follow up in assessing candidate BBH-GRB associations, and present projections for analogous radio studies in the LIGO-Virgo-KAGRA observing run 5 (O5), and in the era of next-generation ground-based instrumentation. The enhanced sensitivity and localization capabilities of detector networks such as Cosmic Explorer and the Einstein Telescope, paired with the enhanced sensitivity of next-generation radio interferometers such as the next-generation VLA and the Square Kilometre Array, will significantly strengthen coordinated multi-messenger follow-up of BBHs. These next-generation facilities are likely to provide an answer to whether BBHs host relativistic ejecta powered by mini-disk accretion.

Aims. Classical Cepheids (CCs) are fundamental standard candles for the extragalactic distance scale through their period-luminosity (P-L) relations. Although well calibrated in broadband systems, their behavior in narrowband filters remains poorly explored. Combining broad- and narrowband photometry can improve constraints on extinction and dust distributions. Methods. We derived multiband P-L relations for more than 8000 CCs in the Magellanic Clouds (MCs) using Southern Photometric Local Universe Survey (S-PLUS) observations in five broad and seven narrow bands. Single-epoch magnitudes were corrected using a framework that simultaneously accounts for relative reddening and line-of-sight depth. P-L coefficients were determined through iterative fitting and maximum-likelihood optimization, with uncertainties estimated from Bayesian Markov chain Monte Carlo analyses for both fundamental- and first-overtone-mode Cepheids. Results. We present the first Cepheid P-L relations in the S-PLUS photometric system. The relations provide consistent distance and reddening estimates across all 12 bands. Their dispersion decreases toward longer wavelengths, while the slopes vary from $\sim-2.0$ to $-2.8$ in the bluest bands and from $\sim-2.9$ to $-3.2$ in the reddest bands. The resulting reddening maps reveal strong spatial extinction variations and recover prominent structures, including 30~Doradus and the H\,I supergiant shell SGS~12 (LMC~3). The inferred orientations of the MCs is consistent with previous studies. Conclusions. Accurate distances and reddening can be recovered from single-epoch multiband photometry when combined with light-curve corrections, enabling high-precision three-dimensional mapping of the MCs.

The rapid appearance of supermassive black holes at high redshift motivates a reassessment of non-baryonic growth channels. We develop a loss-cone framework for collisionless dark-matter (DM) capture by early black-hole seeds, with particular attention to phase-space depletion and refilling. The calculation combines Eddington-inverted NFW-like halos, a relativistic direct-capture boundary, and an orbit-averaged Fokker-Planck treatment of angular-momentum transport. Primordial black holes (PBHs) are treated as massive perturbers whose refilling strength depends on both their abundance and individual mass. Collisionless refilling by triaxial or chaotic centrophilic orbits is included as a phenomenological upper-envelope channel. We show that ordinary stellar relaxation gives negligible DM-driven growth for the fiducial high-redshift seeds. PBH-driven granularity can yield order-of-magnitude growth in sufficiently compact halos, while triaxial or full-loss-cone supply can produce a rapid early burst. In the self-consistent calculations, however, the evolution generally becomes supply-limited. Once the accessible low-angular-momentum phase-space reservoir is depleted, the capture rate collapses and the black-hole mass saturates. Fixed-background NFW calculations therefore overestimate sustained growth, especially in the full-loss-cone limit. A TNG50-calibrated NFW benchmark gives negligible growth even under optimistic refilling assumptions. Collisionless DM capture is therefore unlikely to solve early SMBH growth in generic NFW-like halos, but it can provide a radiatively dark upper envelope in rare compact environments with efficient angular-momentum refilling.

Globular clusters (GCs) host multiple stellar populations with distinct chemical compositions, but their properties among very low-mass stars remain poorly constrained. The James Webb Space Telescope (JWST) enables precise infrared studies that are highly sensitive to abundance variations in cool stars. We initiate a homogeneous survey of Galactic GCs, based primarily on deep JWST GO-8960 observations and complemented by archival JWST and Hubble Space Telescope data, to characterize multiple populations across a wide range of cluster properties. In this first paper, we present the survey and initial NIRCam results. We analyze eleven GCs, deriving high-precision photometry and astrometry to measure proper motions. Multiple populations are detected among low-mass stars in all clusters, with diverse behaviors. We find discrete main sequences in NGC 288, NGC 6723, and NGC 2808, and more continuous distributions in NGC 104 and the Type II clusters NGC 1851 and NGC 6656. The bulge clusters NGC 6528, NGC 6553, and NGC 6440 show patterns consistent with varying helium and oxygen abundances that do not scale simply with cluster mass. In Terzan 5 and Liller 1, we identify populations spanning different ages and helium variations within the old population of Terzan 5. We also detect an M-dwarf gap in NGC 104 around 0.35 solar masses, consistent with the Jao Gap of field stars and open clusters. This work establishes the foundation for a homogeneous JWST survey of Galactic GCs and provides a valuable dataset for studies of cluster evolution, Galactic stellar populations, and background extragalactic sources.

This paper presents a brief overview of studies of magnetic filament formation in the solar convection zone. Two stages of magnetic filament formation and development are distinguished. The first stage can be described within the kinematic approximation for the MHD equation, since the average kinetic energy of convective motion exceeds the average magnetic field energy. Moreover, magnetic Reynolds number is on the order of $10^6$. Therefore, at the initial stage of magnetic filament formation, the magnetic field can be considered frozen-in. It turns out that at this stage, magnetic filaments begin to form at the boundaries of convective cells in hyperbolic regions of the flow. These regions act as attractors for the magnetic field. At the free boundary of the convective zone near the interfaces between convective cells, the magnetic field has a predominantly normal component relative to the boundary. As the magnetic field increases, the field's frozen-in nature in the filament is disrupted, and saturation occurs due to finite conductivity. It is important to note that the magnetic field growth and saturation in the filament at this stage can be determined by analyzing the behavior of the magnetic field at the free boundary, which, according to observations, can be considered flat. Moreover, the formation of magnetic filaments is independent of the internal structure of the convective cells and is determined by the behavior of the convective flow along the free surface. In the next stage, when the magnetic field in the filament is sufficiently strong, the magnetic field pressure gradient begins to impede the convective flow, leading to a shift of the hyperbolic regions toward the convective flow along the free surface. As a result, the transverse size of the filament increases and stops when the kinetic energy density and the magnetic field energy density become comparable.

We present the morphological, photometric, and spectroscopic properties of a z ~ 1 galaxy, "lil gal", serendipitously detected in JWST Mid Infrared Instrument (MIRI) images of nearby galaxy VV 340. In the MIRI F560W and F770W images, we identify what appears to be a spiral galaxy with a central bulge. However, in the F1500W image, a second peak appears ~0.7" northwest (NW) from the central bulge, calling into question the nature of this source as a clumpy disk, a high-redshift interloper, or a galaxy merger. Multi-band analyses of the three MIRI and four Hubble Space Telescope (HST) images suggest a photometric redshift of ~0.92. Spectroscopic analyses of data from the Keck Near-Infrared Echellette Spectrometer (NIRES) reveal two sets of [N II] and H-alpha emission lines corresponding to the two observed sources. A redshift of z = 0.9248 is identified for the NW companion. Fainter emission lines are identified from the underlying galaxy at z = 0.9225, suggesting a merging galaxy pair at a projected separation of ~5 kpc. From the emission line ratios from Keck NIRES and Keck Cosmic Web Imager (KCWI) spectra, we classify the system as hosting regions of active star formation, likely attributed to merger-induced starburst activity. The results demonstrate the necessity of resolved, spectroscopic follow-up analyses of galaxies found in deep JWST images to disentangle the role of galaxy mergers from clumpy disk galaxies at z ~ 1 to cosmic noon and beyond.

Gaia Data Release 3 (DR3) presents a unique dataset with approximately 2.1 million eclipsing binary star candidates. The unsustainability of manually classifying such a large volume of data has necessitated the development of reliable and scalable automated techniques. In this study, a novel multimodal deep learning model has been developed for the automated classification of approximately 2 million eclipsing binary stars in the Gaia DR3 archive based on their light curve morphologies (EA, EB, EW). The developed architecture simultaneously utilizes a Convolutional Neural Network (CNN) that extracts visual features from light curve images and a Multilayer Perceptron (MLP) that processes geometric model parameters. Noise-free synthetic light curves were used during the training process to ensure the model focuses on geometric shapes. Tests showed that the model achieved an accuracy rate of over 95% for all classes, exhibiting excellent separation performance, particularly in EA-type systems. As a result of the automated classification performed with the trained model, 40% of the Gaia DR3 eclipsing binaries were classified as EA, 30% as EB, and 30% as EW. This study provides a highly accurate and transferable classification framework for future large-scale sky surveys.

Large spectroscopic surveys now collect data at a scale that makes traditional visual inspection impractical. We present an unsupervised pipeline for spectroscopic quality assessment that requires no labeled training data. The method combines Uniform Manifold Approximation and Projection for dimensionality reduction with Friends-of-Friends clustering to isolate anomalous spectra for targeted review. We apply this pipeline to 58,291,334 spectra across 14,199 tiles from DESI Data Release 2, processing each tile independently to produce a tile-level outlier catalog. In each tile, the pipeline separates a dense core of typical spectra from small, isolated components and singletons, yielding a total of 1,095,816 outlier candidates. The mean tile-level outlier fraction is about 1.96 percent overall, with values of 0.76 percent and 2.36 percent for the dark and bright main-survey programs, respectively. From the visual inspection of 391 outlier candidates from the dark and bright programs of the main survey, we find that 66.8 percent exhibit identifiable spectral anomalies consistent with known reduction and calibration effects. By contrast, only 4.1 percent carry a non-zero quality flag from the standard reduction pipeline. This shows that the method provides a complementary quality-assessment layer to existing pipeline diagnostics and recovers a substantial population of problematic spectra that standard diagnostics miss. Extrapolating to the main-survey catalog, we estimate that approximately 218,000 candidate outliers are free of identifiable reduction artifacts and may correspond to genuine atypical spectra in the context of DESI. The pipeline is scalable, reproducible, and directly comparable across successive data releases, making it a practical quality-assurance monitor for DESI and future multi-object spectroscopic surveys.

High-redshift little red dots (LRDs) are compact sources characterized by V-shaped spectral energy distributions (SEDs), broad emission lines, and often prominent Balmer breaks. Their high number density and apparently large black hole masses suggest that they are essential to the early evolution of galaxies and supermassive black holes (SMBHs); however, the nature of their central engines remains uncertain. Here, we propose that LRDs are the supermassive, high-redshift analogs of the hyper-Eddington accreting Galactic microquasar SS~433, viewed at high inclinations. By scaling the hyper-Eddington accretion physics from stellar-mass black holes to supermassive scales, we show that the observed LRD features, including X-ray weakness, soft optical SEDs, apparent sub-Eddington accretion ratio, and Balmer breaks, emerge naturally from the self-shielding geometry of a puffed-up accretion disk. In this framework, the broad-line regions are ionized by anisotropic radiation escaping from the inner disk, analogous to the unseen UV/X-ray emission revealed by the W50 nebula in SS 433. Their low-inclination or lower-accretion-rate counterparts would appear as little blue dots (LBDs) or normal active galactic nuclei. Our model predicts that the Balmer break strength positively correlates with the broad-line width, that the emission lines are more variable than the optical continuum, that LRDs are intrinsically more luminous than observed, and that LBDs are more variable than LRDs. This unified-scale model redefines LRDs as the essential laboratories for observing the rapid accretion-driven growth that shaped the early assembly of galaxies and their central SMBHs.

Newtonian noise is expected to be the dominating noise source for low frequencies at the Einstein Telescope. It originates from seismic waves that cause density fluctuations in the rock around the interferometer. The mitigation strategy for Newtonian noise relies on an array of seismometers, placed at depth in boreholes, which provides measurements of the seismic wave field. We optimize the positions of the individual seismometers for the mitigation capabilities of the array for a full corner of the Einstein Telescope. We find that the mitigation capabilities of arrays with multiple seismometers in each borehole match the capabilities of only somewhat smaller arrays but with only one seismometer per borehole. Mitigation is further improved by extending the array with seismometers in the interferometer tunnels. Such configurations may hence provide a cost-effective way towards realizing an efficient seismic array. In each case, we quantify the broadband mitigation performance in the range from 1 to 10 Hz for arrays that are optimized for a frequency of 10 Hz, as well as the robustness of the arrays with respect to variations from their optimized positions. We find that larger arrays with several seismometers per borehole and additional seismometers in the tunnels provide promising broadband performance above 3 to 4 Hz and that such arrays are particularly stable against variations in the seismometer positions with mitigation factors $>6$ for an array of 20 boreholes with 3 seismometers each and $>15$ for a large array of 50 boreholes with 10 seismometers.

We present a study of dwarf galaxy candidates in the deepest optical imaging yet obtained of the field surrounding the nearby galaxies NGC 5068 and NGC 5084/NGC 5087, the latter two located in the peripheries of the Virgo Supercluster. This field, covering $\sim 2.6$ deg$^2$, was observed as part of the multi-band, wide-field and very deep data from VST-SMASH, a distance-limited program ($D < 11$ Mpc) that reaches $g$- and $r$-band surface brightness depths of $\mu \sim 30$ mag arcsec$^{-2}$. Using a two-step visual inspection procedure, we identify 47 dwarf galaxy candidates and perform the surface photometry of the sample and the fitting procedure with 1D Sérsic model on their profiles. Only 4 galaxies were previously reported in the literature, augmenting by one order of magnitude the number of dwarfs discovered in these regions. The colors (median $g-r = 0.57$ and $r-i = 0.24$ mag) and structural properties of the dwarf candidates are consistent with the literature, as are their scaling relations with effective radius, Sérsic index ($n < 2$), and absolute magnitude. We also investigate their central colour gradients, which exhibit significant scatter, and discuss them within the broader context of galaxy formation. We finally analyze their spatial distribution relative to potential host galaxies. We identify reasonable associations with NGC 5084, NGC 5087, and NGC 5068 as likely hosts for a significant fraction of the sample. Several candidates are at physically credible distances from NGC~5068, despite what their offset size-luminosity relation alone might indicate. Future spectroscopic and deeper imaging follow-up is required to determine distances and velocities, enabling robust association with hosts, studies of satellite distributions and counts, and comparisons with cosmological expectations for planes of satellites and dark matter models. (abridged)

The observed abundance of galaxy clusters as a function of mass and redshift provides a powerful route to precision cosmology; a key challenge for cluster cosmology is to establish the relation between cluster observables and cluster masses, for which cluster weak gravitational lensing has become the standard tool. A key challenge for cluster lensing is that the shear signal near cluster centers can reach the non-linear regime, where many shear estimators rely on perturbative assumptions that must be explicitly validated. In this work, we use image simulations to test the performance of the shear estimator AnaCal for cluster weak lensing under conditions representative of the 10-year LSST data. We find that AnaCal recovers the input shear with minimal bias even at mildly high shear, $|g|\sim 0.15$. We discover a radially decreasing mean shear response as seen previously in data, driven by the radial dependence of the convergence field; if unmodeled, this effect can bias shear inference. We also find a positive shear-estimation bias at third order in the reduced shear near the cluster center. However, because only a small fraction of galaxies lie in the high-shear regime and those measurements are further downweighted by the covariance matrix, the resulting mean cluster-mass bias for cluster lens masses in $[10^{14} M_\odot, 10^{15} M_\odot]$ -- adopting a scale cut of $\sim 0.2$ Mpc at $z=0.25$ -- is $0.24 \pm 0.26\%$ under ideal settings. These results demonstrate that AnaCal is a robust tool for accurate cluster mass calibration in the LSST era.

We present a multiwavelength investigation of the molecular cloud complex G12.79+0.43, which extends over $\sim18'$ on the sky. Several infrared- and radio-bright regions are arranged along an irregular rim, surrounding a central region characterised by diffuse 24~$\mu$m emission. CO molecular line observations reveal three prominent velocity components along the line of sight. Low-frequency radio continuum observations at 666 and 1300~MHz show diffuse emission spanning $\sim10.5'$ ($\sim$7.3~pc), predominantly filling the central region enclosed by the infrared-bright structures. We identify 70 compact radio sources and six \hii~regions across the cloud complex, which are likely powered by early B-type ZAMS stars. Using infrared data, we identify a total of 82 YSO candidates, including 28 Class~I sources, distributed across the cloud complex. On larger scales, the kinematics of the molecular gas over a $2^\circ\times2^\circ$ field indicate that G12.79+0.43 is located along the rim of a larger molecular superbubble (diameter $\sim50$~pc) that also encompasses the well-known W33 region. The inferred expansion age of this superbubble is $\sim0.3$~Myr. While the spatial association between G12.79+0.43 and the superbubble is evident, the current data do not allow us to establish a clear causal connection between the superbubble evolution and the ongoing star formation within G12.79+0.43.

We report the first XRISM observation of the low-mass AGN in the nearby dwarf galaxy NGC 4395 ($M_{\rm BH}\sim10^{4-5}\,M_\odot$), complemented by a simultaneous NuSTAR observation. We constrained the continuum by jointly fitting the XRISM/Resolve (2-12 keV) and NuSTAR (3-30 keV) spectra while excluding the Fe K band (5.5-7.5 keV). Relative to this baseline continuum, the time-averaged Resolve spectrum revealed an unresolved neutral Fe K$\alpha$ core with a velocity width of $\lesssim$110 km s$^{-1}$ and an adjacent redward wing. The red wing was well reproduced by an additional relativistically broadened Fe K component. Furthermore, time-resolved spectroscopy with $\approx$87 ks bins showed that the diskline profile varied significantly over the $\sim$400 ks observation. This evolution can be interpreted in terms of changes in the inner radius of the line-emitting region, together with a possible inclination modulation with a period of $\approx$210 ks. If interpreted as Lense-Thirring precession of a tilted inner flow, the observed period would favor the low end of the black hole mass estimates ($M_{\rm BH}\approx9\times10^3\,M_\odot$) and imply a moderate spin ($a\gtrsim0.6$). These results highlight the capability of XRISM to track relativistic disk dynamics in AGNs.

Testing the validity of the cosmological principle's assumption of large-scale isotropy remains crucial for modern cosmology. We investigate the angular distributions of gamma-ray bursts using the GRB catalog from Neil Gehrels Swift Observatory (Swift) for an independent probe of isotropy. Using the HEALPix spherical harmonic decomposition, we estimate the dipole and quadrupole amplitudes and compare them against the null hypothesis obtained from 500 isotropic Monte Carlo realizations. Our results show 2.9$\sigma$ dipole and 7.2$\sigma$ quadrupole amplitude when applied to the raw data. To account for observational biases, we then create an exposure map using the pointing history, roll angle, and the partial coding fraction of the Swift Telescope. Reevaluating the null hypothesis using this map reduces the significance of these anisotropies to less than $1\sigma$. Therefore, our findings confirm statistical isotropy of the GRB sky using the Swift data, consistent with previous studies. We have also made the Swift exposure map publicly available.

In next-generation spectroscopic facilities, high-multiplex fiber positioning systems must operate within highly constrained focal surfaces, such as the Wide-Field Spectroscopic Telescope (WST) requiring 30,000+ fibers across a 1.4-meter surface. The Fiber Location EXtender (FLEX) positioner meets these constraints by improving fiber patrol radii while minimizing telecentric error and positioner spacing for dense clustering and high Multi-Object Spectrograph (MOS) multiplexing. The patented FLEX concept utilizes a superelastic nickel-titanium alloy (Nitinol) inside three concentric, geometrically altered tubes. This construction ensures the tip remains parallel with its base during tilting, while internal routing allows the fiber to run freely along the axis to minimize Focal Ratio Degradation (FRD). Designed for a patrol radius of 2.5x the pitch within the WST architecture, the design delivers a maximum patrol radius up to ~22.5 mm with a telecentric error of less than 0.39 degrees. FLEX utilizes three piezoelectric actuators to provide large radial displacements and precise focus adjustment. To scale this architecture, a modular focal surface layout of 90 identical curvilinear modules has been devised. This layout houses 30,240 positioners across a 2-degree hexagonal field-of-view (FoV), accommodating a central hole for an Integral Field pickoff mirror. Only three support struts are required, obscuring just 0.8% of the FoV while allowing full positioner coverage. One in 16 positioners is allocated for high-resolution spectroscopy, with the remainder split among three low-resolution spectrograph sets; all four sets achieve virtually full coverage of the FoV.

Gamma-ray emission has now been detected from a variety of source classes in the Galaxy, including clusters of young massive stars. RCW 38, a very young embedded massive star cluster, is a case of particular interest: its gamma-ray emission detected up to hundreds of GeV, provided the first observational evidence of high-energy particle acceleration powered exclusively by stellar winds. In this work, we aim to characterize the emission mechanisms responsible for the gamma-ray flux in RCW 38 and to provide estimates of the acceleration efficiency, as well as the fraction of accelerated electrons compared to protons, $K_{ep}$. We present the most comprehensive multi-wavelength study of a single star cluster to date. Our analysis ranges from MHz radio observations obtained with the GLEAM-X survey from the Murchison Widefield Array (MWA) to GeV gamma-ray data from Fermi-LAT, and includes GHz and THz measurements from Parkes, Planck, and IRAS. We model the thermal and non-thermal emission of RCW 38 using an eight-parameter model constrained by the Markov chain Monte Carlo method. Our results support an interpretation in which the gamma-ray emission from RCW 38 is produced by hadronic interactions with the host molecular cloud. We derive robust constraints on the electron-to-proton ratio, with $K_{ep} \lesssim 10^{-3}$, and on the acceleration efficiency, estimated to be $\gtrsim$1%, consistent with the values required to explain the cosmic-ray composition, and in particular its $^{22}$Ne anomaly. These results strengthen the idea that stellar clusters play a significant role as contributors to cosmic-ray protons in our Galaxy at least up to energies of a few TeV. Future investigations with the next generation of ground-based detectors will determine whether they also play a relevant role at higher energies, particularly in the context of the cosmic-ray knee.

We present a new all-sky model of low-frequency diffuse Galactic emission in the regime where synchrotron, free-free, and spinning dust dominate. The model extends the Planck 2015 diffuse component-separation analysis by incorporating recent radio and microwave surveys. We fit 35 full- and partial-sky maps at 1 degree resolution, including S-PASS at 2.30 GHz, C-BASS at 4.76 GHz, and QUIJOTE at 10-20 GHz, together with reprocessed WMAP and Planck LFI data from the Cosmoglobe collaboration and Planck HFI channels. Using a Bayesian parametric approach with Commander, we derive spatially varying amplitude and spectral parameter maps for the dominant low-frequency foreground components in total intensity. The main products are a full-sky synchrotron amplitude and spectral-index solution, an all-sky characterization of spinning dust emission with a single-component log-normal spectral model, and a reconstructed all-sky total-intensity map at 4.76 GHz tracing diffuse synchrotron emission with reduced systematics relative to Haslam 408 MHz. The revised low-frequency anchoring increases the recovered synchrotron amplitude: at 4.76 GHz, it is approximately a factor of two higher than the Planck 2015 prediction. The model achieves RMS temperature residuals below 10 $\mathrm{\mu}$K over 95% of the sky up to 353 GHz, with fractional residuals below 1.5% in the Galactic plane and below 5% across QUIJOTE bands. Residual angular power spectra lie more than two orders of magnitude below the CMB spectrum. These products describe the transition between radio and microwave emission and provide a new reference for foreground modeling and sky-simulation applications.

We report the discovery of [CII] 158 micron emission in and around the most distant known massive quiescent galaxy RUBIES-UDS-QG-z7 at z = 7.27. Observed with ALMA in band 6, the [CII] line independently confirms the spectroscopic redshift from JWST/NIRSpec spectra at low and medium resolution. The emission extends over an effective radius R_eff,[CII] = 8 +/- 3 kpc, well beyond the compact stellar body traced by JWST/NIRCam (R_eff = 209 (+33/-24) pc), with a significant fraction of approximately 70% of the flux arising from a circumgalactic halo. No dust continuum is detected at rest-frame ~160 micron, setting an upper limit on the infrared luminosity of L_IR < 1.4 x 10^11 Lsun, overall consistent with expectations from rest-frame UV to near-infrared SED modeling under energy balance. Converting the galaxy-scale [CII] emission into cold gas mass, we find log(M_mol/Msun) = 9.53 (+0.32/-0.31) and log(M_HI/Msun) = 9.46-10.34, depending on the assumed calibration and metallicity. Despite being approximately 10x more gas-poor than typical star-forming galaxies at fixed redshift, stellar mass, and [CII] to gas mass conversion, RUBIES-UDS-QG-z7 retains a substantial cold gas reservoir with fractions f_gas >~ 20% and long depletion timescales across most assumptions. The extended [CII] halo carries approximately twice as much gas as the galaxy alone and shows a blueshifted velocity offset consistent with the tentative gas outflow detected in MgII absorption in previous work, suggesting a past episode of AGN-driven gas expulsion possibly linked to the suppression of star formation. The presence of a large gas reservoir in and around a massive quiescent galaxy just 700 Myr after the Big Bang implies that whatever mechanism is suppressing star formation must be remarkably effective at maintaining a low star formation efficiency on ~100 Myr timescales, even in the presence of abundant fuel.

The dimensionless tidal deformability, $\Lambda$, of neutron stars (NSs), inferred from gravitational-wave (GW) observations, has thus far been used primarily to constrain the pressure of dense matter near twice nuclear saturation density, leaving the core equation of state (EOS) largely inaccessible to inspiral-phase GW observations. We show that the core EOS can be probed directly through $\Lambda$ using a perturbative analysis of the dimensionless stellar-structure and tidal-response equations formulated in terms of scaled intrinsic variables, without invoking any specific EOS model. We uncover a remarkable EOS-insensitive scaling relation between $\Lambda$ and the central EOS parameter $\mathrm{X}\equiv P_{\rm c}/\varepsilon_{\rm c}$, where $P_{\rm c}$ and $\varepsilon_{\rm c}$ denote the central pressure and energy density, respectively. The relation is validated against a broad ensemble of physically viable EOSs. Applying it to tidal deformabilities inferred from events such as GW170817 enables a direct determination of $\mathrm{X}$. We further derive a tight lower bound, $\Lambda_{\rm{TOV}}\gtrsim 9.2^{+1.2}_{-1.2}$, for maximum-mass NSs along stable mass-radius sequences, quantitatively demonstrating that even the most compact stable NSs remain distinctly separated from black holes, for which $\Lambda_{\rm{BH}}=0$. These findings reveal a previously unrecognized connection between inspiral-phase tidal deformability and the core EOS, establishing a direct link between GW observables and the microphysics of ultradense matter in the strong-gravity regime. The resulting scaling establishes inspiral-phase tidal deformability as a direct and largely model-insensitive probe of the EOS of NS cores.

Context: With Gaia's third Data Release (DR3), low-resolution BP/RP (XP) spectra became available for more than 219 million sources. In previous work, we developed a fast method for detecting absorption and emission lines while measuring their equivalent widths directly from the XP spectral coefficients. Aims: Our aim is to conduct a systematic search for H$\alpha$ emitters in the Gaia DR3 XP spectra. Methods: We measured the equivalent width of the Balmer H$\alpha$ line for all sources with Gaia XP spectra, and selected an initial sample of 556100 sources depicting an H$\alpha$ emission-like feature at 2$\sigma$ level or above. Using a semi-supervised classifier complemented by manual spectral labelling, we removed sources that merely masqueraded as emission-line stars. Results: We find that 95% of the initial candidates are most likely cool M-type stars, where a molecular absorption band gives rise to a local maximum that can mimic H$\alpha$ emission. Subsequently, 28394 sources are flagged as bona-fide H$\alpha$ emitters using the Gaia DR3 XP spectra. The majority are Be-like candidates (26287), active M-type stars (717), Herbig Ae/Be candidates (525), quasi-stellar objects (204), Wolf-Rayet stars (177), cataclysmic variables (51), and carbon stars (18), among other sources. Our equivalent widths and stellar classifications are in good agreement with results from higher-resolution studies and recent Gaia XP spectra-based catalogues. Ground-based spectroscopic follow-up for some of the newly found emitters reinforces our confidence in the catalogue.

The radio--X-ray correlation and Fundamental Plane (FP) of black hole activity can serve as a diagnostic tool for the origin of X-ray emissions. There was a scaling relation between radio and X-ray emissions for High-synchrotron-peaked BL Lacertae objects (HBLs), i.e., $L_{\rm{R}}\propto L_{\rm{X}}^{0.64}$, which can be explained by ADAF-dominated mode or synchrotron cooling (Syn-c). However, many results of studying blazar physics show that the X-ray emissions of HBLs are mainly produced by the synchrotron process of jets. Therefore, Syn-c appears to provide a plausible explanation for this relation. To further clarify the origin of X-ray emissions of HBLs, we constructed a sample containing 69 HBLs in this paper to re-investigate their radio--X-ray correlation and FP. Considering the Doppler beaming effect, we find that the intrinsic radio--X-ray correlation and FP of HBLs are $L_{\rm R,int}\propto L_{\rm X,int}^{0.68}$ and $\log L_{\rm R,int}=(0.57\pm0.06)\log L_{\rm X,int}+(0.33\pm0.11)\log M_{\rm BH}+(12.65\pm2.00)$, respectively. Our results agree with the scaling relation mention above, which suggests these scaling relations are not artificial. By employing the theoretical model of Syn-c, we find that these shallow radio--X-ray correlations and FP are caused by Syn-c, which implies that the X-ray emissions of HBLs may be produced by rapidly cooling, high-energy electrons accelerated at a shock. This is consistent with results of the recent X-ray polarization observations of HBLs. Our results provide the observational evidence of $L_{\rm R}\propto L_{\rm X_{\text{Syn-c}}}^{0.6\sim0.7}$.

X-ray observations are a primary probe of the intracluster medium, widely used to infer galaxy cluster masses and scaling relations. We present and validate a pipeline to generate X-ray emission maps of galaxy groups and clusters from large cosmological simulations, and use it to study the origin of deviations from self-similarity across the group-to-cluster transition. We apply this pipeline to the Illustris-TNG300 and MillenniumTNG simulations, constructing \mbox{X-ray} emission maps and spectra based on APEC cooling functions. For simulations that do not explicitly track individual chemical abundances, we introduce a metallicity-based prescription that accurately reproduces the full spectral emission. We derive the $L_{\mathrm{X}}$--$M_{500}$, $M_{\mathrm{gas}}$--$M_{500}$, and $T$--$M_{500}$ scaling relations over $10^{12.5} \leq M_{500} \leq 10^{15.5}\,\mathrm{M}_\odot$, compare them with observational data, and quantify the hydrostatic equilibrium and spectroscopic temperature biases through synthetic X-ray analyses. The simulated scaling relations are in good overall agreement with observations and are best described by broken power laws with a pivot at $M_{500}=10^{13.67}\,\mathrm{M}_\odot$. At high masses, the slopes are close to self-similar expectations; at lower masses the relations steepen significantly, reflecting the growing importance of AGN feedback. X-ray hydrostatic masses are systematically underestimated by $15\%$, independently of cluster mass. When spectroscopic effects are included, the bias becomes mass-dependent, ranging from $15\%$ at low masses to $21\%$ at high masses. The recovered X-ray luminosity, measured in the $0.15$--$1\,R_{500}$ aperture, is also mass-dependent: high-mass clusters are underestimated by $18\%$, while low-mass systems show discrepancies of up to $33\%$, driven by single-temperature spectral modelling of the gas outside the core.

We present a cosmological reassessment of light sterile-neutrino scenarios, examining whether current observations exclude sterile neutrinos as a class or primarily constrain the fully thermalized case. We consider three distinct realizations: (i) a fully thermalized sterile species (FTS), (ii) a thermal relic with a suppressed temperature relative to the active neutrino background (DTS), and (iii) a Dodelson-Widrow-like (DW) sterile neutrino with reduced phase-space normalization. Constraints are derived within both LambdaCDM and the CPL dynamical dark-energy framework using combinations of Planck CMB data, DESI DR2 BAO measurements, and the PantheonPlus and Union3 Type Ia supernova samples. For baseline data combinations without a local H0 prior, the FTS scenario is strongly disfavored in both cosmological models. Adding the local H0^DN prior allows LambdaCDM+FTS to accommodate the high local H0 value and become statistically competitive with standard LambdaCDM once SNIa data are included, although the sterile-neutrino mass remains consistent with zero. By contrast, partially populated sterile-neutrino scenarios remain viable: the DW realization is broadly compatible with current observations, while the DTS scenario yields the weakest cosmological pressure among the cases considered. Overall, cosmological data mainly require a strongly suppressed effective sterile abundance, leading to tight constraints on m_eff^sterile while allowing substantially weaker bounds on the physical sterile mass. We conclude that current observations do not generically exclude sterile neutrinos, but rather place strong pressure on fully thermalized or highly populated scenarios, highlighting the importance of production history and phase-space distribution when interpreting cosmological constraints.

Wave-optics interference in strongly lensed gravitational waves is a new interferometric probe of dark matter substructure: a subhalo population threading a galaxy-scale lens imprints frequency-dependent distortions on the amplification factor of each macro image. In a companion paper (arXiv:2603.04267), we computed these imprints for the magnified minimum image. Here, we extend the calculation to the saddle-point image and we assess the detectability of the combined signal with the Laser Interferometer Space Antenna (LISA). Evaluating the amplification factor at a saddle is numerically delicate, because the equal-arrival-time contours are open and the subhalo signal is a small difference of large terms; we present a time-domain method that resolves it. Across a Monte Carlo ensemble of cold dark matter subhalo realizations, subhalos induce percent-level amplitude and phase modulations in both image parities, while the mean (de)magnification splits by parity: the minimum is net magnified and the saddle net demagnified. Demodulating the macro-image interference recovers the per-image modulations, and a matched-filter analysis that projects out the lens parameters yields a combined detection above $5\sigma$ in $62\%$ of realizations for fiducial massive-black-hole-binary sources of total mass $\sim10^{6}\,M_\odot$ at redshift $1.5$, provided the source lies close to the lens caustic at small impact parameter $y_{\rm src}\lesssim0.1$. Folding these naive per-event significances through optimistic strong-lensing rate forecasts yields $10$-$20$ substructure detections over the LISA mission. Strongly lensed gravitational waves are thus a sensitive, complementary probe of substructure at $10^{4}$-$10^{7}\,M_\odot$ scales inaccessible to electromagnetic observations.

Interstellar water (H$_2$O) ice exhibits significantly varied profiles over its spectral features with temperature and thermal history. No previous radiative transfer model of a protoplanetary disk has fully accounted for these effects over 3 - 200$\mu$m simultaneously. A radiative transfer model with region-based distribution of ices and applicable ice optical constant composites (OCCs) is required to properly model the distribution and spectral signatures of water ice in disks. We build such H$_2$O ice OCCs by combining multiple experiment measurements of the imaginary refractive indices, $k$, to cover from 0.1 - 10,000$\mu$m and perform Kramers-Kronig (KK) integrations to derive updated real refractive indices, $n$. We construct H$_2$O ice OCCs for two thermal histories: first, direct deposit and measure at a fixed temperature ices (DT) and deposit and cool down (DC) ices, for five and eight distinct temperatures, respectively. Next, we self-consistently apply these within a radiative transfer model of a protoplanetary disk according to its thermal structure. This produces the first self-consistent RT profiles for the two most commonly used spectroscopic tracers of thermal processing of H$_2$O ice. To assess the impact that appropriate H$_2$O optical constants have on the 3$\mu$m absorption and 45 and 63$\mu$m emission profiles, we run four RADMC-3D radiative transfer models of edge-on class II disk, HH 48 NE. The four models each use different OCCs; the standard single temperature crystalline and amorphous H$_2$O ice OCCs available from OpTool and our own multi-temperature DT set of OCCs and DC only set of OCCs. We find that ices must have been thermally processed at temperatures higher than the local disk temperature in order to produce crystalline spectral profiles at 3, 45 or 63$\mu$m in disks, suggesting local heating events or outward transport to colder regions.

Protoplanetary disks evolve in clustered environments where interactions with nearby stars and interstellar gas are common. Such environmental processes, including stellar flybys and gas infall, can significantly perturb disk structures over the disk lifetime and potentially influence the evolution of embedded planets. We investigate how environmental interactions affect the architecture of Class II systems that host both a disk and already-formed planets, and assess their impact on disk structure and dynamics, as well as planetary evolution. We performed 3D simulations using the Phantom smoothed particle hydrodynamics (SPH) code, including multiple dust species treated with a dust-as-particles approach that accounts for dust back-reaction on the gas. We modeled a disk hosting two planets in a 2:1 mean-motion resonance and subjected the system to two types of perturbations: an infalling gaseous cloudlet and a stellar flyby. Infall and flyby perturbations change the disk morphology and dynamical state. Infalling gas increases the disk mass and angular momentum, dynamically exciting the dust and producing eccentric, multi-ring dust structures. The stellar flyby truncates the disk, compacting the dust distribution radially and enhancing episodic radial migration of dust grains. These processes excite eccentricity in both gas and dust, leading to distinct accretion pathways for the planets. In particular, the flyby promotes inward dust migration, which may enhance solid accretion onto the planets, while infall preferentially increases the accretion rate of the inner planet. Environmental interactions during the Class II phase can reshape disk-planet systems, imprinting dynamical signatures that may persist into later evolutionary stages. Both late infall and stellar flybys can lead to the formation of eccentric and narrow debris disks and influence the growth and composition of planets.

TIFUUN (THz Integral Field Units with Universal Nanotechnology) is an ultra-wideband mm-submm wave imaging spectrometer that capitalizes on the highly scalable integrated superconducting spectrometer technology. TIFUUN has two slots for integral field units (IFUs), which can jointly be optimized as open-hardware for each astronomical observation in terms of spatial and spectral coverage. These IFUs can have observation frequencies in the range of 90--360 GHz, with spectral resolution up to $R\equiv F/\Delta F \le 1,000$, with up to $\sim$18,000 kinetic inductance detectors (shared by the two IFUs with a flexible ratio). The ultra-wide 4:1 (2 octave) bandwidth optics fits in a remarkably compact volume, by means of thin silicon lenses and a high chief ray angle design. The first pair of IFUs are being developed for the SUBLIME (Study of the Universe By Line Intensity Mapping Experiments) experiment that aims to map CII emission at redshift $\sim$6 to trace the cosmic large-scale structure and the buildup of galaxies during reionization, using TIFUUN on the ASTE 10-m telescope. The scalability, flexibility and compactness makes TIFUUN a highly compatible and portable system suited also for upcoming telescope facilities in the vicinity, such as FYST and AtLAST/LST.

The Carruthers Geocorona Observatory -- launched in September 2025 -- is NASA's first mission devoted to investigating the fundamental nature of Earth's exosphere from its distant vantage in halo orbit around the Earth-Sun L1 Lagrange point. Its primary payload, the GeoCoronal Imager, consists of two coaligned photometric imagers that measure ultraviolet Lyman-alpha emission radiance from exospheric hydrogen simultaneously at wide- and narrow- fields of view. The imagers use Micro Channel Plate intensified Complimentary Metal Oxide Semiconductor detectors, which are known to add various artifacts to the final image telemetered from the spacecraft, hereby known as instrument effects. This paper details the algorithms used to retrieve and remove instrument effects from raw telemetry on-orbit, including detector voltage bias, thermal dark current, particle radiation, flat-field, and distortion. Finally, the science data processing pipeline from raw telemetry to instrument-effect corrected images is detailed. Algorithm performance is measured via a synthetic numerical image generator or validated on pre-launch experiments.

We present time-series observations of the split comet 240P/NEAT near perihelion, obtained using the Nordic Optical Telescope. The brighter component, 240P-A, has an estimated radius in the range 400 m to 600 m, and loses dust at the peak rate 130 kg/s. The ejected dust has characteristic size 50 micron, is expelled sunward at 25 m/s, with a total ejected mass in the period of observation 1.5x10^9 kg. Mass loss from the fainter component, 240P-B, peaks at 35 kg/s and the total ejected mass was 2.3x10^8 kg. The radius of 240P-B is uncertain, with a best estimate about 300 m and an absolute lower limit 50 m. 240P-A and 240P-B are currently separating at about 1 m/s, a speed that is likely accelerating as a result of differential outgassing forces, and have a separation age over 3 years. The splitting of 240P is incompatible with the action of tides, impact, and internal pressure build up. 240P fits a developing picture, in which small comets are destroyed by rotational instabilities triggered by outgassing torques, an explanation that can be tested in 240P by future observations.

We present an analysis of a sample of 36 Little Red and Blue Dots (LRDs and LBDs) at $2.26<z<7.89$, identified by JWST in the GOODS fields. While both categories are selected to have broad Balmer lines, both of them are extremely X-ray weak. Both classes share the same location on various diagnostic diagrams, consistent with AGN excitation (with some deviations which can be ascribed to low metallicity), although their weak HeII emission suggests a generally softer ionizing spectrum than ordinary AGN. LRDs display Ly$\alpha$ emission stronger than normal star-forming galaxies, and with a broad component consistent with the broad component of H$\alpha$. Overall, these findings indicate that LRDs and LBDs are both powered by growing black holes and their ionizing radiation escapes to ionize the surrounding interstellar medium (ISM). The broad Balmer lines ($H\alpha_b$ and $H\beta_b$) have different apparent properties: LBDs have EW(H$\alpha _b$) and $H\alpha_b/H\beta_b$ broadly consistent with normal AGN, while LRDs have higher values of both quantities, although still in the tail of the quasars distribution. LRD models in which a gas envelope completely encases the black hole, are inconsistent with these results -- these scenarios need modification to include clumpiness, or a (classical) equatorial geometry, letting ionizing photons reach the ISM. The different broad Balmer properties imply that LBDs cannot simply be LRDs with more galaxy contribution. Scenarios in which LRDs are simply dust-obscured LBDs seem broadly consistent with the observations. Finally, these results indicate that LRDs' bolometric luminosities estimated assuming isotropic emission and complete covering by the absorber are inadequate. The few X-ray-detected LRDs suggest no deviation from the standard AGN bolometric corrections, once absorption is accounted for.

We present an analytical stationary isentropic solution of the spherically symmetric Euler equations in the gravitational field of a star using an equation of state of ionizable monatomic gas. The solution consists of a fully ionized hydrostatic inner region, followed by a thick hydrostatic recombination region where the density decreases by orders of magnitude, the radius increases by about an order of magnitude and the temperature decreases by a factor of two. Within this recombination region, a large portion of the recombination energy is used for lifting the gas subsonically. This region ends at a critical point, located roughly at $10-100~\rm{AU}$, where the gas is mostly recombined, beyond which it flows supersonically as a wind. We find the position and the quantities of the gas at the critical point and derive the mass-loss rate of the solution. We apply our solution to evolved stars, with a compact core surrounded by a high entropy envelope. We derive the mass-loss rate as a function of time. As the star is losing mass, it goes through a sequence of our solutions, in a runaway manner which ends once most of the high entropy envelope is lost. The recombination-driven winds are initiated once the stars expands to a radius of about $1~\rm{AU}~M/M_\odot$ and are terminated on a timescale of $10^1-10^4~\rm{years}$. We discuss the implications for common envelope evolution.

Hot Neptunes are close-in exoplanets that occupy a sparsely populated region of parameter space known as the "hot-Neptune desert". Their presence in this extreme environment is puzzling as it implies a complex history involving intense stellar radiation, atmospheric loss, and unique migration patterns, different from Neptunes at larger orbital periods. We are running an observational programme conceived to enlarge the number of close-in Neptune-sized planets, with well-measured physical and orbital parameters, with the aim of contributing to obtaining a statistically significant sample needed to clarify what the formation and migration pathways of this class of exoplanets are. We used currently available TESS photometry, along with new (HARPS-N) and archival (HIRES) high-precision radial-velocity measurements, to review the main properties of the planetary systems TOI-1272 and TOI-1694 by means of joint-fit analyses that, in the case of TOI-1272, included Gaussian-process regressions for carefully modelling stellar activity. Our final estimates of the parameters of the two systems are consistent with previous measurements but have smaller uncertainties. We identified the radial-velocity variation of TOI-1272 found in the HIRES data as stellar activity rather than planetary in nature and, therefore, rejected the non-transiting planet TOI-1272c. This opens up the possibility that TOI-1272b's eccentricity is the result of high-eccentricity migration. The larger number of data at our disposal also allowed us to point out that both TOI-1694b and TOI-1694c move on slightly eccentric orbits. The current orbital architecture of TOI-1694 suggests a history of migration driven by both disc and dynamical interactions.

We present the evolution of the resolved mass-weighted age, stellar metallicity, and sSFR of 872 Milky Way Analog (MWA) progenitors up to redshift $z=5$ from the Canadian Unbiased Cluster Survey (CANUCS). The metallicity and mass-weighted ages were obtained via spatially resolved SED-fitting with the non-parametric code Dense Basis. We split the sample into mergers versus non-mergers using the merger parameter from the Gini-$M_{20}$ plane obtained through Gini-$M_{20}$ analysis of the morphology of the stellar mass maps with Statmorph. Across our redshift range, non-mergers have negative or flat average age gradients from $-0.022$ to 0.005 dex/kpc, and positive or flat sSFR gradients from $-0.089$ to 0.092 dex/kpc, consistent with inside-out assembly. The average $\log(Z/\Zsun)$ gradients for non-mergers range from $-0.029$ to 0.044 dex/kpc, however, positive gradients only appear between $2 < z < 3$. At every redshift epoch, mergers typically have flatter age gradients, more negative sSFR gradients, and similar metallicity gradients compared to non-mergers. We divide the property maps of ongoing mergers into separate regions based on their component galaxies, and find little to no difference between the components' average ages or metallicities, but the less massive of the merging system is on average $0.1-0.4$ dex higher in sSFR. Our results point to major mergers contributing some momentary disruption to the general trend of inside-out mass assembly, but does not upend the overall picture of MWA disks growing inside-out over cosmic time.

We revisit the growth of central black holes via tidal disruption events (TDEs) and plunges of stellar-mass black holes (sBHs). Our model incorporates the current understanding of mass segregation, where sBHs sink to the center, enhancing the rates of both TDEs and plunges. We demonstrate that in dense cluster cores, with densities exceeding $10^6\,\mathrm{M_\odot\,{pc}^{-3}}$, seeds of initial mass $M_0\gtrsim100\,M_\odot$ undergo runaway growth. This runaway terminates once the black hole radius of influence surpasses the core radius, or equivalently, most of the core mass has been consumed. This typically results in an intermediate-mass black hole (IMBH), within a few $\mathrm{Gyr}$. Subsequent growth proceeds as a power law. In contrast to observed supermassive black holes (SMBHs), which tightly follow the famous $M \propto \sigma^\beta$ with $\beta \cong5$, our derived sBH accretion rates, integrated over a galactic lifetime, predict final masses of $M\approx10^5\,M_\odot \times(\sigma/50\mathrm{km\;s^{-1}})^{2.5}$. While our prediction for the contribution of plunges to the growth of the IMBH is robust, the TDE contribution can be negligible if only a small fraction of their mass is actually accreted or up to 3 times higher than the plunges contribution if half a stellar mass gets accreted in each event. Below $M\sim10^5\,M_{\odot}$ this accreted star and sBH mass exceeds the extrapolation of the observed $M$-$\sigma$ relation. This predicts that the $M$-$\sigma$ scaling must flatten below $M \sim 10^5\,M_{\odot}$ to a shallower, $2.26<\beta<2.5$ profile. If confirmed by observations, this would indicate capture-driven growth.

Resolving the impact of magnetic field instabilities in triggering small scale turbulent flow and the associated rearrangement of the field is of critical importance in understanding multimessenger observables in binary neutron star mergers, and angular momentum transport in neutron stars and accretion disks. Direct simulation of these instabilities are unfeasible, however large-eddy simulations can incorporate the impact of this turbulence with a subgrid model. We present the first machine-learning-based subgrid model for special relativistic magnetohydrodynamics, trained using a neural network. We demonstrate its performance in online simulations of the 3D Kelvin-Helmholtz instability through both a priori and a posteriori tests. Evaluated in a low resolution simulation, our model captures magnetic field amplification of a simulation at 4 times the resolution with a speed-up of a factor 44. This demonstrates the applicability of such methods in general relativistic simulations of neutron star mergers and other scenarios.

It is commonly assumed that the spin-orbit angles of binary black holes (BBHs) originating from dense stellar environments rapidly converge to an isotropic distribution following a number of strong gravitational encounters. We challenge this assumption by modeling the evolution of the BBH orbital angular momentum orientation through successive binary--single encounters as a random walk on the unit sphere, yielding an exact solution for the orientation distribution after $n$ encounters and a closed-form expression for the number of encounters required to reach isotropy. To characterize the step distribution, we conduct a large suite of Newtonian point-particle scattering experiments with an equal-mass binary, varying the mass of the single, and obtain semi-analytic expressions for both the mean step size and the full distribution of steps. Applying these results to BBHs with initially aligned spins, as may arise from the evolution of primordial massive binaries, we find that spin-orbit alignment can survive several strong encounters before being erased. This has direct implications for the slight trend toward spin-orbit alignment reported in GWTC-5.0 as well as for the retention of hierarchical merger products, such as the components of GW231123.

Long-term records of the Martian atmosphere based on general circulation models and reanalysis of atmospheric state variables are important to understand the diurnal, seasonal, and climatological changes of the planet. Atmospheric dynamics of the Martian atmosphere are strongly influenced by the characterization of dust lifting, solar insolation, and spatial variations in topography. We present ARCO-Mars, a unified Analysis-Ready Cloud-Optimized dataset providing integrated access to three independent Mars atmospheric reanalysis products: EMARS, MACDA, and OpenMARS spanning over Mars Years 24-35. These reanalyses assimilate thermal infrared retrievals from the MGS/TES, ODY/THEMIS, and MRO/MCS instruments, providing both two and three-dimensional surface and atmospheric state variables, including temperature, winds, surface pressure, and dust optical depth. The dataset is stored in Zarr v3 format and hosted on HuggingFace, enabling efficient cloud-based access without requiring local storage of the full archive. We compare the state variables between the three reanalysis products to identify systematic differences, attributed to differences in data assimilation and general circulation models. ARCO-Mars provides a community resource for Mars atmospheric science, numerical weather prediction validation, and machine learning applications, including weather forecasting and data assimilation.

The scientific utility of large single-dish radio telescopes depends critically on the stability and fidelity of their beam patterns, which govern angular resolution, sensitivity, and polarimetric accuracy. For the 32-m Ghana Radio Astronomy Observatory (GRAO) antenna, electromagnetic simulations reveal residual sidelobes, structural diffraction, and cross-polar leakage that limit performance in high-dynamic-range and polarisation-sensitive observations. To address these limitations, we develop a finite-impulse-response (FIR) spatial filtering framework that reformulates beam optimisation as a digital signal processing problem. By exploiting the equivalence between angular displacement and spatial frequency, classical FIR design methods, window-based and Parks-McClellan algorithms are adapted to operate directly on simulated Jones fields. This approach enables controlled suppression of high spatial frequency artefacts responsible for sidelobes and polarisation mixing, while preserving the telescope's diffraction-limited resolution. Applied to the GRAO 5 GHz beam model, the method achieves substantial reductions in near-in sidelobe ripple, improves beam smoothness, and lowers cross-polar leakage below -30 dB at boresight. These improvements translate into enhanced calibration stability and polarimetric precision, strengthening the telescope's capacity for Very Long Baseline Interferometry, spectral-line surveys, and pulsar timing. Beyond GRAO, the method provides a generalisable, non-invasive, and computationally efficient pathway for beam control applicable to other single-dish and phased-array instruments. The results establish digital spatial filtering as a practical complement to conventional optical or mechanical optimisation, advancing the integration of electromagnetic modelling and signal processing in next-generation radio astronomical instrumentation.

The James Webb Space Telescope (JWST) has recently revealed evidence of supermassive black holes (SMBHs) forming in the cores of high redshift galaxies that grew in mass extremely rapidly during the first billion years of the universe. In this study we present a new solution where the growth mass factor of BHs, $\gamma(t) \propto \dot M_{BH}/M_{BH}$, varies with time, following the changes of radiative efficiency, $\epsilon$, and Eddington ratio, $\lambda_{Edd}$, caused by the variation in accretion flow. By optimizing the accretion rate, $\dot M_{BH}$, we obtained a solution that is universal, that is, which applies to any BH at any redshift. This suggests that the mass of the BH is a thermodynamics state function, in good agreement with the no hair theorem and the four laws of mechanics of BHs.

We report an ab initio and master-equation investigation of the gas-phase reactions of thioformaldehyde (H2CS) with CN and CCH radicals, motivated by the recent detection of the S-containing species HCSCN and HCSCCH in cold interstellar environments. Structures and frequencies were obtained at the DSD-PBEP86/aug-cc-pVTZ level, with energetics refined by CCSD(T)-F12a calculations and kinetics treated using an energy-grained master equation. The CN + H2CS reaction proceeds through orientation-dependent entrance channels. Two barrierless addition pathways lead to a connected multi-well network that preferentially forms cyano thioformaldehyde, HCSCN + H, whereas abstraction-type channels leading to HNC + HCS or HCN + HCS contribute only marginally. The calculated kinetics indicate capture-controlled low-temperature reactivity and a strong preference for HCSCN formation, suggesting that this reaction should be considered in astrochemical models of cold clouds. For CCH + H2CS, barrierless capture gives access to two connected entrance adducts. Although the cyclic product is the most exothermic channel, its formation is kinetically hindered by a high-lying late transition state. The flux is shared between propynethial formation, HCSCCH + H, and the HCCH + HCS channel, with the latter being favored. These results show that subtle differences in radical structure, bonding preferences, and entrance-channel topology strongly affect product branching in S-containing radical-molecule reactions. The computed mechanisms and rate coefficients provide useful input for astrochemical models of sulfur chemistry in cold molecular clouds and for interpreting recent molecular detections in sources such as TMC-1.

One of the most striking findings of exoplanetary science is the ubiquity of clouds. A conventional approach to infer the cloud compositions is to utilize the thermochemical equilibrium model assuming the same temperature shared with clouds and ambient gases; however, this assumption is actually not always valid, especially in the tenuous upper atmospheres where particle-gas collisions are infrequent. In this study, we investigate the radiative equilibrium temperatures of exoplanetary clouds to assess the thermal stability of aerosols in the low atmospheric pressure limit. For eight cloud-forming condensates (KCl, ZnS, Na$_2$S, MnS, SiO$_2$, Mg$_2$SiO$_4$, Fe, and Al$_2$O$_3$), we solve the energy balance between stellar radiative heating and infrared cooling to calculate the particle temperature, which is then compared with their condensation temperatures. We find three composition-dependent groups in the particle-temperature behavior, and show that silicate condensates (SiO$_2$ and Mg$_2$SiO$_4$) maintain a cool enough temperature in a wide range of stellar and planetary conditions. Conversely, sulfide condensates (ZnS, Na$_2$S, and MnS) are readily heated to their sublimation temperatures even on temperate planets. WASP-17b and HD 189733b fall within the thermodynamically stable regime for SiO$_2$ clouds, consistent with recent JWST observations. We also examine the vertical profiles of cloud temperatures on WASP-17b, showing that Fe clouds cannot exist on the dayside, and Al$_2$O$_3$ clouds can exist only in a confined region, even though atmospheric temperature appears to allow the formation of these clouds. This study provides novel insights on cloud compositions in upper exoplanetary atmospheres, testable by upcoming atmospheric surveys of JWST and Ariel.

Wide-field surveys like Euclid mark a new era of extragalactic stellar stream studies. With a large number of streams, it is now possible to constrain the dark matter halos of galaxies in a cosmological volume and draw comparisons to theoretical expectations for the geometry of dark matter halos. This study combines Euclid imaging with visual detection and segmentation annotations to analyse streams. We use projected stream morphologies to constrain the shape and centre-of-mass position (CoM) of each host galaxy's potential, jointly probing baryonic and dark matter distributions. These inferences complement weak lensing methods, with sensitivity to halo profile and geometry on sub-virial scales. The method enables both stacked, population-level constraints on halo flattening and CoM position, and constraints on these quantities for individual halos. We also present a novel method for transforming segmentation maps of stellar streams into smooth, curvature-preserving tracks optimised for fast and robust dynamical inference. This approach enables rapid modelling of stream morphology, supports a statistically rigorous combination of constraints across multiple streams within a single galaxy, and enables joint inference across galactic hosts. From our study of 13 galaxies with prominent tidal streams, we find agreement with spherical halos, albeit a mild preference for flattening with $q = 0.95^{+0.05}_{-0.10}$ at 68\% confidence. This is promising early agreement with $\Lambda$CDM predictions. With thousands more discovered streams expected across \Euclid's mission, our programme will enable precise measurements of halo shapes and CoM positions across large samples and redshifts, offering constraints on the geometry of dark matter halos.

We present an analysis of the chromospheric emission of Fe I + Fe II in the wing of the Ca II K line of 21 G and K giant stars. Stellar parameters and absolute chromospheric fluxes were obtained by comparison with PHOENIX models. The iron-blend emission shows a proportionality with the Ca II K flux for stars with similar stellar parameters and also for individual stars observed at different epochs, confirming that both diagnostics seems to respond to the same underlying chromospheric conditions. We found a dependence of the iron-blend emission on stellar parameters by fitting a power-law relation. The exponent of the effective temperature statistically matches with that found for Ca II K; which, together with a metallicity dependence, indicate that the iron-blend may act as an indirect tracer of chromospheric thermal conditions. The chromospheric emission flux ratio (Fe I + Fe II)/Ca II K exhibits a distinct slope change around log g approx. 2.5 dex; which causes the gravity dependence to be different for stars with gravities lower and higher than 2.5 dex. This behavior suggests a transition between regimes where the two diagnostics probe similar physical conditions and where they begin to diverge in the sensitivity to the chromospheric extension. We discuss the implications of this behavior for the thermal structure of the lower chromosphere and for the formation heights of both diagnostics.

The understanding of the mechanism(s) by which massive stars collapse and possibly explode is rapidly maturing. Uncertainties in the structure of the stellar core at the onset of collapse are often dominant in numerical simulations, and a limited number of progenitor grids are available. This is especially true for explosions where rotation and magnetic fields play a significant or primary role. We present a grid of 113 single-star models with initial masses $M_{\rm ZAMS}=30-90\,M_{\odot}$ and initial rigid rotation $\omega_{\rm ZAMS}=0.5-0.99\,\omega_{\rm crit}$ computed at $Z=0.001$ with the open-source stellar evolution code \textsc{MESA}. We adopt a 128-isotope nuclear reaction network capable of following the weak reactions deleptonizing the core during and after silicon core burning. By construction, these models experience rotationally-induced chemically-homogeneous evolution, and reach the onset of collapse ($v_{\rm infall}\lesssim -300\,\mathrm{km\ s^{-1}}$) with large and structured amounts of angular momentum, possibly sufficient to form accretion disks on a proto-compact object. Therefore, these progenitor structures provide a homogeneous set of models with updated input physics and improved algorithmic accuracy to understand stellar explosions of (some types of) stripped-envelope supernovae, possibly jetted and/or broad-lined, collapsars or magnetar-powered, and/or long $\gamma$-ray bursts.

Recent baryon acoustic oscillation measurements from DESI provide important new clues for reassessing whether the standard $\Lambda$CDM model offers a sufficient description of the late-time expansion history of the Universe. When combined with cosmic microwave background and type Ia supernova data, these measurements show an apparent departure from the $\Lambda$CDM model, commonly described as dynamical dark energy (DDE) with equation of state crossing the phantom divide (i.e., quintom behavior). This review examines the current status of the DESI-motivated indications for DDE and their possible implications for physics beyond $\Lambda$CDM. We discuss how the strength of the preference for DDE depends on the adopted parametrization and dataset combination, and how residual systematics or internal tensions among datasets may affect its interpretation. At the background level, several mechanisms beyond $\Lambda$CDM can produce similar expansion histories. We therefore further discuss how the same effective departure from $w=-1$ may arise from physically distinct scenarios, including interacting dark energy, non-minimally coupled gravity, and non-standard dark matter. Meanwhile, these different new-physics interpretations may have different implications for current cosmological tensions, especially those involving $H_0$, $S_8$, and $\sum m_\nu$. In conclusion, the question posed by DESI is not merely whether dark energy evolves with time, but rather how, within the framework of precision cosmology, to disentangle new physics scenarios from systematic errors.

Broadband observations with the {\em Fermi} mission reveal that a large fraction of gamma-ray burst (GRB) spectra are dominated by non-thermal emission, while a small fraction are dominated by thermal/quasi-thermal emission, likely indicating the difference in jet composition among GRB. By selecting two typical long GRBs (080916C and 090902B) and two short GRBs (130603B and 090510), we present a comparative analysis to investigate whether the composition of prompt GRB jets influences the afterglow emission for bursts originating from both massive star collapse and compact binary mergers. Incorporating emission from both primary and cascade electron populations, we fit the multi-wavelength afterglow lightcurves of these GRBs with the standard forward shock model and analyze the particle acceleration and radiation physics of the jets. Our results show that the afterglow lightcurve evolution with the characteristic parameters is not related to the composition of the GRB fireball but rather depends on the ambient medium density. The early UV-optical afterglows of the two long GRBs are dominated by synchrotron emission from cascaded $e^{\pm}$ pairs produced via the $\gamma\gamma$ annihilation process, whereas this is not the case for the two short GRBs. These results suggest that the internal energy of the fireball is converted into jet kinetic energy during the prompt phase, and that the fireball composition leaves no detectable footprint on the afterglow jet. Instead, the density of the ambient medium plays an essential role in shaping the afterglow emission.

One path to understand how planets form is to link their present-day atmospheric composition to predictions from planet formation models. For the hottest planets, the abundances of refractory species can provide a useful formation tracer, complementing the traditionally used C/O and overall metallicity. Here we investigate the refractory abundance in the atmosphere of the ultra-hot Jupiter WASP-121 b, combining new JWST MIRI/LRS observations with archival NIRSpec/G395H and NIRISS/SOSS data to obtain a panchromatic dayside emission spectrum from 0.6 to 12 $\mu$m. Our retrieval analysis detects the refractory tracer SiO gas at high confidence, in addition to previously detected volatile species. The atmosphere is enriched in volatile and refractory species, with enhanced refractory-to-volatile ratios of Si/O=$3.54^{+0.86}_{-0.69}$x stellar and Si/C=$3.05^{+1.12}_{-0.80}$x stellar, relative to new stellar abundance constraints from ESPRESSO data. In addition, we confirm the depletion of TiO and the need for an additional source of reflected light opacity with a geometric albedo of $0.22\pm0.03$. The retrieved dayside temperature profile has a strong inversion layer, with a more complex structure than standard parameterizations can accommodate, and an eclipse map analysis indicates a small eastward hotspot offset of $4.8^{+2.7\circ}_{-2.8}$. Comparing our results with models of planet formation, we find that the measured enrichment pattern was shaped by accretion from multiple reservoirs, either through a mixture of solid and gas accretion interior to the water ice line or through continued solid accretion during inward migration from farther out in the disk. Finally, we model the planet's dynamical history and find that it could reach its current high-obliquity orbit as a consequence of a post-formation dynamical event, such as planet-planet scattering or von Zeipel-Lidov-Kozai cycles.

Tessellation methods are extensively employed in the analyses of cosmic large-scale structure (LSS). However, these techniques are highly sensitive to perturbations in both densities and positions of points, often leading to substantial rearrangements of tessellation configurations. As a result, considerable additional statistical errors are introduced in various tessellation-based statistics, thereby weakening their cosmological constraints. In this work, we identify this issue and propose an efficacious measurement scheme through subsampling and averaging to enhance the stabilities of tessellation-based statistics. As a case study, we apply the new scheme to measure multiple primary void statistics [i.e., void size function (VSF), void two-point correlation function (VTCF), and void power spectrum (VPS)] in two distinct classes of voids, based on Delaunay and Voronoi tessellations, respectively. We notice that the statistical uncertainties in void statistics can be predominantly attributed to tessellation instabilities. Through rigorous testing, we demonstrate that the proposed method can substantially eliminate these scatters to deeply mine the statistical power of void statistics. Specifically, we find that our method can dramatically boost the signal-to-noise ratios (SNRs) of void Baryon Acoustic Oscillations (BAOs) and significantly improve the constraining power of void statistics on cosmological parameters. These findings showcase enormous application potentials of our new method in maximizing extraction of cosmological information from galaxy surveys. Importantly, our method is simple yet highly potent with broad applicability, hopefully evolving into a standard framework for measuring tessellation-based statistics in the future.

A parameter used to characterise star formation activity in MCs is the efficiency per free-fall time, $\epsilon_{\rm ff}$, although commonly referred to as an efficiency, it is formally the ratio between the star formation rate (SFR) and the gas-infall rate. Here we numerically study the collapse of cores and define $\epsilon_{\rm ff}\equiv\langle\dot{M}_\star\rangle/(M_{\rm core}/\tau_{\rm ff})$, where $\langle\dot{M}_\star\rangle$ is the average SFR, $M_{\rm core}$ is the gas mass within the core (as the gas cells above a density threshold), and $\tau_{\rm ff}$ is the free-fall time of the core gas. We perform simplified numerical experiments of the gravitational collapse of an isolated core, varying the initial mean number density ($n_0=100$ and $1000~\rm cm^{-3}$) and adopting closed/open BCs to (dis)allow fresh gas accretion into the domain. The simulations start with a slight central Gaussian overdensity that evolved into a power-law profile, $n\propto r^{-p}$ with $p\to2$. As the collapse proceeds, a sink particle forms in the center of the core. We find that both the BCs and the adopted core definition modify the measured core properties and, consequently, the inferred $\epsilon_{\rm ff}$. Low-density models have less mass available, and their accretion histories are therefore much more sensitive to the choice of BCs, while high-density runs, with their larger mass reservoirs, maintain similar accretion histories regardless of the BCs. In all models, after sink formation, $\epsilon_{\rm ff}$ rises and then remains relatively stable while accretion continues to replenish the core's mass, but increases once the gas reservoir is exhausted. Somewhat counterintuitively, $\epsilon_{\rm ff}$ is higher in the low-mass cores, since the larger gas infall rates onto the high-mass cores compensate for their higher SFR. We conclude that the inferred $\epsilon_{\rm ff}$ depends sensitively on both the adopted core definition and external mass supply

Solar flares, particularly those of the M- and X-class, have a significant impact on human life because of their potential to disrupt critical infrastructure and communication systems on Earth. Accurate prediction of solar flares is crucial for mitigating these risks, but the black-box nature of conventional deep learning models used in flare prediction limits their trustworthiness and interpretability. In this paper, we propose a new approach to solar flare prediction using photospheric magnetic field parameters or features with deep learning. To improve model interpretability, we integrate explainable artificial intelligence (XAI) techniques, including SHapley Additive exPlanations (SHAP) and partial dependence plots (PDPs), into our prediction framework. XAI methods provide transparency by analyzing the importance and interactions of features used by our model. Specifically, SHAP values offer a global and local understanding of the features, while PDPs provide insights into feature-level trends. These techniques demonstrate the potential of XAI in deploying AI-driven solutions in high-impact applications such as solar flare prediction, paving the way for more informed decision-making in solar physics and space weather studies.

this http URL limb darkening encodes the thermal and radiative structure of stellar photospheres and is a key ingredient in modeling transit light curves and transmission spectra. It was recently shown that stellar surface magnetic fields modify limb darkening in stars with near-solar fundamental parameters, and that only magnetic models can reproduce high-precision transit observations for such stars. However, for stars with non-solar fundamental parameters, the magnitude of the magnetic effect on limb darkening remain unconstrained. this http URL aim to investigate how surface magnetism affects stellar limb darkening across a range of fundamental parameters and to provide the community with center-to-limb spectra of stars at different magnetization levels. Methods. We use the MPS-ATLAS code to compute synthetic spectra from 3D radiative magnetohydrodynamic box-in-a-star simulations performed with the MURaM code. These simulations self-consistently capture photospheric magneto-convection without relying on ad hoc parameterizations. We perform calculations for main-sequence stars at solar metallicity with effective temperatures in the range Teff = 3200 - 6800 K. For stars with solar effective temperature we also consider metal-poor, M/H = -1.0, and metal-rich, M/H = 0.5, cases. Results. We show that the magnitude of the magnetic effect depends strongly on stellar fundamental parameters, increasing toward hotter and more metal-rich stars. Overall, limb darkening is significantly affected by magnetic fields in K, G, and F dwarfs, while the effect becomes negligible in M-dwarfs. We release a public database of synthetic spectra at 10 disk positions.

We present an analysis of the intraday flux and spectral variability of BL Lacertae from 2020 September 30 to 2024 December 7, covering its highest recorded brightness and low, intermediate, and high flux states. Our study involved 62 nights of multi-band (BVRI) optical monitoring using four ground-based telescopes located in Egypt, Türkiye, and Bulgaria. We assessed intraday flux variability using the power-enhanced F-test and the nested ANOVA test. Significant variability was detected in 88 out of 117 light curves, consistent with previous studies of this object during active epochs. The maximum variability amplitude is 44.5 per cent in the B band. Spectral analysis reveals a bluer-when-brighter trend during intraday flares, supporting a synchrotron origin for the variable emission. For a subset of well-sampled flares, we model their profiles with a double exponential function, deriving rise and decay time-scales, thereby constraining the characteristic times of particle acceleration and cooling processes within the relativistic jet. Assuming a turbulent jet model, we determined limits on the radii and magnetic field strengths of the emitting regions. We detected soft time lags for a multi-band flare and from their analysis, derived the Doppler factor and magnetic field strength of the corresponding emitting region. Our long-term, high-cadence study confirms that BL Lacertae was in an exceptionally active phase during the 2020-2024 period, with intraday variability being a common phenomenon. The results underscore the dynamic nature of the jet emission region and provide valuable observational constraints for models of blazar variability and jet physics.

PKS 1725+123 is a flat-spectrum radio quasar (FSRQ) with a redshift of $z=0.586$. The detection of this object in the TeV band was reported by the MAGIC telescopes and H.E.S.S. in August 2025. Subsequently, we promptly initiated Target-of-Opportunity observations using the Space-based multi-band astronomical Variable Objects Monitor (SVOM) satellite. By analyzing the observational optical data from SVOM-VT and comprehensively examining the Fermi-LAT and Swift-XRT observational data, it was found that the source is in a high-flux state across the optical, X-ray, and GeV $\gamma$-ray bands around the time of the TeV detections. Its optical flux reaches a historically unprecedented high level and shows significant variability on timescale as short as minutes. The variability is accompanied by changes in the color index, exhibiting a \textit{bluer when brighter} behavior during the high-flux state. Based on the simultaneous multi-wavelength data, we construct the broadband spectral energy distribution (SED) of the source in the high-flux state. PKS 1725+123 demonstrates a remarkably high synchrotron peak frequency, which is distinctly different from that of other FSRQs. We propose a two-zone spine-sheath jet model to reproduce this SED. The optical--X-ray emission is generated by the synchrotron process of the relativistic electrons within a compact zone. The inverse Compton (IC) scattering processes of the same electron population contribute to the low-energy end of the Fermi-LAT spectrum, while the high-energy end of the Fermi-LAT spectrum is ascribed to the IC scattering of the synchrotron photons within the compact zone by the higher-energy electrons in an extended region.

We analyse physical and chemical structure of the hot molecular core RCW120 S2, based on high-sensitivity (2-4 mK) APEX observations at 1.3 mm. The analysis reveals a rich molecular inventory, including complex organic molecules (COMs) such as CH$_3$OH, CH$_3$CHO, CH$_3$OCHO and CH$_3$OCH. We derive gas temperatures (20-300 K), H$_2$ densities (10$^4$-10$^7$cm$^{-3}$), and molecular column densities. The detected emission probes a radially stratified envelope, with cooler (<= 60 K) and less dense (10$^4$-10$^5$cm$^{-3}$) outer layers traced by SO, SO2, and c-C$_3$H$_2$, while warmer (60-100 K) and denser (10$^5$-10$^7$cm$^{-3}$) inner regions are traced by H$_2$CO, OCS, and low-excitation CH$_3$CN. The hot gas (<= 100 K) exhibits broad (8-10 km/s) lines from high-excitation CH$_3$OH, CH$_3$CN, HDO, and CH$_3$OCH$_3$. Relative molecular abundances of COMs generally agree with astrochemical hot-core models, while methanol appears underabundant and CH$_3$CN overabundant compared to predictions. We attribute these discrepancies to the need for interferometric observations at intermediate spatial scales to resolve the core's true filling factor and radial gradients.

We investigate a quintessence dark-energy model with an exponential potential and an exponential coupling to cold dark matter (CDM), hereafter referred to as the CQ-EXP model, using Planck CMB, DESI BAO, and DES-Dovekie supernova observations. We also examine how variations in the neutrino mass sector affect the constraints. When the neutrino mass sum is fixed at $\sum m_\nu=0.06$ eV, the data favor a coupling between quintessence and CDM, with the coupling parameter $\beta$ deviating from zero at more than $3\sigma$. In particular, the observations favor the $\beta<0$ branch, where the energy transfer between the two dark sectors changes sign and the effective equation of state (EoS) of dark energy crosses the phantom divide, $w=-1$. When the effective neutrino mass parameter $\sum m_{\nu,\mathrm{eff}}$ is treated as a free parameter, the data show a preference for negative values of $\sum m_{\nu,\mathrm{eff}}$. This additional freedom weakens the preference for the coupling between quintessence and CDM and leads to nearly identical values of $\chi^2_{\rm min}$ for the CQ-EXP models with $\beta>0$ and $\beta<0$, corresponding respectively to models without and with phantom-divide crossing in the effective EoS. Both values are slightly larger than that obtained in the $w_0w_a$CDM model, indicating that the CQ-EXP model cannot be statistically distinguished from the $w_0w_a$CDM model with the data considered here. Therefore, when $\sum m_\nu$ is fixed, current observations favor the CQ-EXP model with phantom-divide crossing. In contrast, when negative values of $\sum m_{\nu,\mathrm{eff}}$ are allowed, a CQ-EXP dark energy without crossing $w=-1$ can also provide an effective explanation of the latest observations.

Magnetic fields thread the interstellar medium from the largest to the smallest scales and play an important role in molecular cloud evolution and star formation. Quantifying this requires measurements of the field strengths, and the most direct way to measure them is via the Zeeman effect in spectral lines. The effect is subtle for the typical field strengths expected from theory, from a few $\mu$G in diffuse molecular clouds to a few 10s of mG in dense star-forming regions, and detections are scarce. Existing measurements of magnetic field strength suggest dense clouds and cores are marginally supercritical (cannot prevent collapse, but can inhibit it), but may be biased due to small sample sizes. Zeeman effect measurements tracing different scales and densities within molecular clouds can reveal the variation of field strengths, providing critical measurements to address the question of whether star formation is primarily regulated by magnetic fields or turbulence on different scales. Observations with SKA precursors such MeerKAT and FAST are beginning to increase the number of Zeeman effect detections in nearby star-forming regions. The SKA will extend their reach to many regions within our Galaxy that are best representative of where most stars form, while zooming in on the densest star-forming regions, providing a statistical basis for the role of magnetic fields in molecular cloud evolution and star formation. We present predictions and plans for Zeeman effect observations with the SKA telescopes, demonstrating the significant advances they will provide for studies of magnetic fields in molecular clouds.

Warm inflation is usually expected to completely deplete the inflaton condensate by dissipating its energy into radiation. We show that this expectation fails in a simple and observationally viable regime. In a strongly dissipative warm inflationary scenario, the dissipative ratio, $Q=\Upsilon/(3H)$, can fall rapidly after the end of inflation as the system approaches radiation domination, thereby suppressing further energy transfer to the thermal bath. This leads to a residual inflaton condensate, which subsequently evolves as an effectively non-dissipative scalar field. For potentials with a stable quadratic minimum, this remnant inflaton manifests as a cold dark matter component. We establish this mechanism for the minimal renormalizable potential, with a dissipative coefficient $\Upsilon\propto T^3$. In this case, current cosmological data allow strong dissipation while leaving the inflaton mass weakly constrained by inflationary observables. The observed dark matter abundance then fixes its mass to be $m \approx 0.02\,{\rm MeV}$, while larger masses overclose the Universe. The transition to matter-like scaling occurs well before BBN, avoiding a long-lived inflaton dark radiation component. Relic inflaton dark matter therefore turns the post-inflationary dynamics of warm inflation into a new late time constraint on its parameter space.

Spacecraft operations scheduling is a highly constrained, long-horizon combinatorial optimization problem that traditionally relies on heuristics, constraint programming, or manual planning. We present a scalable deep reinforcement learning framework developed and deployed for NASA's Carruthers Geocorona Observatory mission. Our framework introduces a macro-action abstraction known as activity blocks coupled with dynamic action-masking to navigate the intractably large search space and strictly enforce complex power, thermal, and instrument constraints. The resulting architecture generates globally feasible schedules with overwhelming probability, establishes operational trust, and executes a full training cycle in under six hours, circumventing the need for policy robustness by enabling rapid, on-demand retraining. Further, resulting schedules outperform baseline heuristics in scheduled science quality. The deep reinforcement learning framework was deployed as the default operational scheduler for the Carruthers Geocorona Observatory mission from the outset of the mission, demonstrating that deep reinforcement learning can be trusted for real spacecraft operations under complex, evolving constraints.

Large astronomical observatories are increasingly adopting distributed peer review (DPR) to manage growing proposal volumes, yet empirical comparisons with panel-based systems remain limited. Beginning in 2021 (Cycle 8), the Atacama Large Millimeter/submillimeter Array (ALMA) transitioned to DPR for the majority of proposals, with DPR applied to nearly all proposals from Cycle 9 onward. Under DPR, each Principal Investigator (PI) designates a reviewer to evaluate a set of proposals without collective discussion. This study analyzes over 20,000 proposals and 160,000 reviews spanning 13 cycles to assess the impact of this change. We find that DPR largely reproduces the systematic ranking trends observed in panel evaluations across PI demographics, technical characteristics, and scientific areas, consistent with panel outcomes both before and after discussion. Scientific diversity among the top-ranked proposals is similar between DPR and post-discussion panel rankings. Individual proposal ranks show substantial dispersion under both DPR and panel assessments prior to discussion, with discussion only partially reducing this variance. The observed dispersion therefore reflects intrinsic variation in reviewer judgments rather than a byproduct of the distributed process itself. In Cycle 12, reviewers rated the majority of DPR written comments as high or adequate quality, with no dependence on reviewer career stage. However, 10% of reviews were rated as low quality, highlighting the challenge of maintaining quality standards across the approximately 16,000 reviews produced each cycle. Overall, our results indicate that DPR reproduces the population-level ranking structure obtained in panel review, despite differences in review mechanics and the role of discussion.

(Abridged.) The local environment of a Type Ia supernova (SN Ia) encodes information on progenitor age, star formation, dust, and chemical enrichment that may influence both its light-curve properties and its standardized luminosity. We assemble a homogeneous explosion-site dataset to test how near-ultraviolet (UV) imaging combined with optical integral-field spectroscopy improves the characterization of SN Ia environments and their connection to SN observables. We analyze 340 low-redshift SN Ia sites observed with HST/WFC3 F275W and matched VLT/MUSE spectroscopy. For each site we measure local photometry, extract a 1 kpc-aperture spectrum, model the stellar continuum with a joint UV+optical fit, derive local stellar and gas-phase properties, and fit the SN light curves with SALT3-NIR. UV emission is detected at 235 of the 337 sites with valid HST imaging. The UV- and Halpha-based SFR surface densities are strongly correlated, with the UV estimates systematically higher by about 0.5 dex. Including the UV constraint shifts local luminosity-weighted ages toward older values by a median of +0.20 dex for UV detections and +0.45 dex for UV non-detections, showing that UV data help break age-dust-metallicity degeneracies. Consistently, F275W-r is very strongly correlated with the joint-fit stellar age. Within the 169-SN Ia calibration sample, the joint stellar age, the Halpha specific SFR, and the UV specific SFR all correlate strongly with the SALT3 stretch parameter x1, with significances above 6.8 sigma. After standardization, Hubble-residual trends are weaker, with amplitudes of about 0.04-0.06 mag. The results support a primary age-stretch mechanism largely absorbed by standard light-curve corrections, while any residual luminosity dependence on local environment is weaker and subtler.

We present the multiwavelength variability of the BL Lac object PKS 0735+178, associated with the high-energy neutrino event IC211208A. The light curves cover the radio (1-230 GHz), optical, and Fermi-LAT $\gamma$-ray bands over a $\sim$30 years time-scale. The light curves are correlated, with delays from 0 to 1200 days increasing towards lower frequencies, consistent with emission from an opacity-stratified jet. The bright flare after the IC211208A event indicates emission from a compact, optically thick region with enhanced activity and more efficient particle acceleration. Short optical and $\gamma$-ray bursts have been detected very close to the neutrino event, within a few days. The $\sim$12-day lag between the $\gamma$-ray and optical emissions is detected for the first time, suggesting that the emission regions are not co-spatial. A characteristic variability time-scale of $\sim$10-11 yr is robustly detected in the radio-mm bands ($\geq3\sigma$), while the optical and $\gamma$-ray data show weaker, shorter-period signals. The independent constraints from the VLBI core-shift measurements and radio time delays yield consistent estimates of the jet geometry and disturbance propagation, supporting variability governed by jet propagation effects. The long-term modulation is consistent with a slow variation in energy release at the jet base, while individual flares arise from shocks propagating downstream. Jet precession may contribute to the long-term modulation; however, the required viewing angles are inconsistent with the VLBI constraints, indicating that precession alone cannot explain the observed variability.

IGR J17480-2446 is a low-mass X-ray binary, harboring an exceptional accreting pulsar (a neutron star) with an unusual spin frequency of 11 Hz and a very slow post-outburst crust cooling. The former may imply that it is observed at an early stage of recycling, while the latter was shown to indicate the presence in the outer crust of a low thermal conductivity layer, possibly made of glass. Here we argue that the glass layer formation is a natural result of accretion induced failure of pristine cold crystal crust. This allows us to determine the mass of the accreted material as $\Delta M \approx 2.4\times 10^{-6}~M_\odot$, confirming very early accretion stage for this neutron star. An analysis of spin and thermal state reveals a peculiar set of neutron star birth properties which is commonly associated with `recycled' neutron stars, i.e.\ those that have been experiencing prolonged periods of accretion from a companion. We speculate that such birth properties may represent the outcome of neutron star formation in an electron-capture supernova.

We present a novel method to conduct targeted gravitational-wave searches for compact binary mergers using the GstLAL inspiral pipeline. By incorporating sky localization and timing information from external electromagnetic triggers, we enhance the sensitivity of the search for sub-threshold gravitational-wave signals associated with events such as short gamma-ray bursts. Our approach modifies the standard likelihood ratio ranking statistic to include a sky localization prior, allowing for a more focused analysis on specific regions of the sky. We demonstrate the effectiveness of this method through injection studies, comparing the performance of the targeted search against the standard all-sky search configuration. The results show a significant improvement in detection efficiency for signals consistent with the provided sky location and timing, while maintaining control over false alarm rates. This targeted search framework enables rapid follow-up of electromagnetic transients, facilitating multi-messenger astronomy efforts in the era of advanced gravitational-wave detectors.

Accurate NH3 pressure-broadening parameters are essential for reliable line-by-line simulations in atmospheric sensing, combustion diagnostics, and planetary/exoplanet studies. Current HITRAN NH3 self- and air-broadened half-widths rely largely on the Nemtchinov rotational correlation and database rules that clamp or assign default values beyond the validated range, limiting the representation of measured rotational trends, especially at high J''. Here, published NH3 self- and air-broadened Lorentz half-widths were compiled and reassessed to develop updated HITRAN-ready empirical correlations. The dataset includes 1317 self-broadened and 1231 air-broadened widths at, or reduced to, 296 K across multiple bands, branches, and rotational states. The analysis shows that linewidths are governed mainly by rotational dependence rather than branch, band, or vibration-inversion effects. Weighted, positivity-constrained third-degree polynomial fits were developed for gamma_self and gamma_air as functions of the branch-dependent index m and K''. The new correlations reduce the MAPE from 10.95% to 6.80% for air broadening and from 23.61% to 10.89% for self broadening relative to HITRAN2024. Comparisons with PNNL and pure-NH3 spectra further confirm improved absorption simulations, providing a physically constrained replacement for the current HITRAN NH3 broadening treatment.

We investigate cosmic anisotropy within the updated Pantheon+ sample using both the dipole fitting (DF) and hemisphere comparison (HC) methods. With the DF method, the dipole signal within the full sample is statistically weak. However, the low-$z$ subsample yields a dipole signal of $A_{\mathrm{D}} = 0.952^{+0.454}_{-0.403} \times 10^{-3}$ at $\sim 2\sigma$ significance, pointing towards $(l,b) = (149.77^\circ, -12.20^\circ)$. This signal is predominantly driven by a combined subset of surveys 5, 56, 63, and 150, which is characterized by an amplitude of $A_{\mathrm{D}} = 1.730_{-0.715}^{+0.554} \times 10^{-3}$ towards $(l,b) = (153.05^\circ, -1.25^\circ)$. For the HC method, the full sample yields a maximum anisotropy level of $\mathrm{AL}_{\mathrm{max}} = 0.289 \pm 0.052$ oriented towards $(l,b) = (127.97^\circ, 17.90^\circ)$ with a $1.56\sigma$ significance. This preferred direction is primarily determined by the highly inhomogeneous SNLS subsample, whereas the low-$z$ and high-$z$ subsamples act to suppress the anisotropy level along this axis. These subsample-dependent results suggest that the apparent anisotropy arises from local structures or the inhomogeneous distribution of the datasets rather than an intrinsic cosmic anisotropy.

We report the discovery of a bow-shock pulsar wind nebula (PWN), dubbed Thunder, powered by the radio pulsar PSR J1631-4722 and projected within the Galactic supernova remnant (SNR) G336.7+0.5 (Nimbus). The system was first identified in observations from the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey and further characterised using MeerKAT Galactic Plane Survey data together with follow-up observations at 5.5 and 9 GHz obtained with the Australia Telescope Compact Array (ATCA). Assuming a distance of 7 kpc, the radio images resolve an elongated ~80 arcsec (2.7 pc) cometary nebula, indicative of a high velocity pulsar. An X-ray counterpart extending ~50 arcsec (1.7 pc) is detected in archival XMM-Newton data. The flat radio spectrum ($\alpha$ = -0.27 $\pm$ 0.05) and hard X-ray photon index ($\Gamma$ = 1.6 $\pm$ 0.4) indicate synchrotron emission from relativistic particles injected in the pulsar wind. Polarisation analysis reveals a highly ordered magnetic field aligned with the nebular flow, with fractional polarisation reaching up to 30% in the tail. An equipartition estimate gives a PWN magnetic-field strength of Beq $\approx$ 54-140 $\mu$G. Pulsar timing over a ~2.2 yr baseline reveals strong timing noise and a small spin glitch with amplitude $\Delta{\nu}/{\nu}$ = 1.10$\times$10$^{-8}$. The SNR shows no clear diffuse X-ray counterpart. The morphology and multiwavelength properties of the Nimbus-Thunder system, along with evolutionary models, constrain the system's age to approximately 30-45 kyr, placing the remnant in the late Sedov phase, approaching the transition to the radiative stage.

With the community's increasing interest in the cislunar space, building a navigation constellation servicing the whole cislunar space has become a pressing need. Previous studies mainly focus on constellations using orbits close to the Moon, which limits the servicing volume of the constellation. In this work, a four-satellite constellation using one L3 orbit, one L4 orbit, one L5 orbit and an orbit close to the Moon is proposed. The orbit determination accuracy is an important factor to be considered when designing parameters of the constellation. In this study, the mode of autonomous orbit determination (AOD) based on inter-satellite range data is considered. With such a model, the out-of-plane design parameters are identified as the main parameters influencing the AOD accuracy. For the AOD based on short arcs, we find that the increase of the out-of-plane amplitude can improve the AOD accuracy, and the out-of-plane initial phases have a more complex influence. A novel relative planarity factor (RPF) $P_\text{r}$, which has negative correlation with the AOD accuracy, is proposed as the metric to evaluate the variation of AOD performance. Using $P_\text{r}$, we demonstrate that the coplanarity of the constellation can significantly reduce the AOD accuracy. For the long arc AOD, the influence of different parameters is insignificant.

The Fermi bubbles have been identified as a collimated bipolar outflow emanating from the Milky-Way center, tracing strong forward shocks which extend $\sim10$ kpc from the Galactic disk, originating from a $\sim10^{56\pm1}$ erg outburst. These shocks are sufficiently strong, extended, and energetic to produce a detectable flux of $\gtrsim 10$ TeV neutrinos, especially in their denser north and east, but early IceCube data were insufficient for identifying the signal. We find that IceCube high-energy starting events (HESE 12-year) correlate with the $\textit{Fermi}$-LAT sky map outside the Galactic plane ($>3\sigma$). Testing for neutrinos coincident with the bubble shells, localized using $\textit{eROSITA}$ data, we detect ($>4\sigma$) both bubbles at high ($|b|>30^{\circ}$) latitudes, with a local excess ($>5\sigma$) mainly in their X-ray bright eastern shells. The signal matches the anticipated secondaries of relativistic ions carrying $\sim 10^{54.5}$ erg (with factor $\sim3$ uncertainty) in each bubble, shock-accelerated to $>$PeV energies. The results verify the strength of the shocks, suggesting an ion acceleration efficiency of order $\sim10\%$. We also present preliminary evidence for neutrinos from the even larger shells of the eROSITA bubbles, which encapsulate their younger Fermi-bubble counterparts, carrying a similar energy and confined by shocks nearly as strong.

Fast radio bursts (FRBs) are luminous, millisecond-duration extragalactic radio transients that have emerged as a powerful, complementary cosmological probe for investigating the late-time cosmic evolution, offering unique advantages over conventional probes such as Type Ia supernovae, baryon acoustic oscillations, and cosmic microwave background radiation. This review systematically summarizes the cosmological applications of FRBs, focusing on their critical roles in measuring the Hubble constant ($H_0$) and constraining dark energy properties. Benefiting from the precise dispersion measure (DM) - redshift relation of localized FRBs, the integrated electron density of the intergalactic medium (IGM) along the line of sight can be tightly modeled, enabling independent and low-redshift measurements of the cosmic expansion rate. Current FRB samples consisting of localized and non-localized events provide competitive $H_0$ constraints, offering an independent method to measure $H_0$. FRBs also serve as effective tracers to constrain dark energy equation-of-state parameters. We comprehensively discuss key limiting factors for FRB cosmological precision, including uncertainties in Galactic and host galaxy electron density models, and IGM inhomogeneities. With the rapid growth of high-precision FRB surveys and localized FRB samples, FRBs are promising to provide stringent constraints on late-time cosmic acceleration, dark energy evolution and cosmic baryons.

We present a global unbinned-likelihood analysis of the rest-frame ultraviolet (UV) quasar luminosity function (QLF) over $0.1\le z\le7.5$, using a final analysis sample of 70,960 Type~1 quasars selected from the homogenized compilation of Kulkarni et al. (2019). We test a shape-preserving luminosity and density evolution (LADE) framework, in which the local luminosity function (LF) shape is fixed and the redshift evolution is described by separate density- and luminosity-evolution factors. For a double-power-law (DPL) local LF, we search 81 LADE models built from nine density-evolution and nine luminosity-evolution functions, and compare them with two flexible double-power-law (FDPL) reference models. The fiducial shape-preserving LADE model gives the lowest Akaike information criterion (AIC) and Bayesian information criterion (BIC) values among the main models considered, and 12 DPL-based LADE models have lower AIC and BIC values than both FDPL reference models. Repeating the model-grid analysis with a modified-Schechter local LF gives the same preferred evolutionary structure, indicating that the result is not driven only by the assumed local LF shape. The fitted evolution functions further show that the luminosity-evolution component is the more stable part of the LADE decomposition: it rises rapidly to $z\simeq2$--3 and then flattens or slowly declines. The density-evolution component is more model dependent, but the preferred LADE models consistently require a declining effective normalization toward high redshift. Taken together, we conclude that a shape-preserving framework offers a statistically efficient and compact empirical description of the global UV QLF.

We present the first measurement of the angular two-point correlation function \(w(\theta)\) of radio sources from the MeerKAT Large Area Synoptic Survey (MeerKLASS) UHF on-the-fly (OTF) continuum Data Release~1. DR1 provides interferometric Stokes-\(I\) imaging at a reference frequency of 816\,MHz over \(\sim 800~\mathrm{deg}^2\) within the DESI footprint. We detect a positive clustering signal over \(0.02^\circ \lesssim \theta \lesssim 10^\circ\). The measurement is stable to reasonable variations of the depth mask and flux threshold on intermediate and large scales. Modelling the intermediate-scale signal (\(0.112^\circ\le\theta\le 1.36^\circ\)) with a fixed-slope power law (\(\gamma=1.8\)) yields \(A(1^\circ)=(1.434\pm0.475)\times10^{-3}\), corresponding to \(\log_{10}A=-2.843^{+0.124}_{-0.175}\). We infer an effective large-scale bias by fitting \(\Lambda\)CDM projected-matter templates \(w_{\rm DM}(\theta)\) computed with \textsc{CAMB} and Limber projection, including an integral-constraint correction evaluated from random--random weights. Using two bracketing T-RECS redshift-distribution priors, we obtain \(b_{\rm eff}=1.998\pm0.350\) (AGN prior) and \(b_{\rm eff}=1.530\pm0.265\) (TOTAL prior), demonstrating that the dominant modelling uncertainty arises from \(N(z)\). As a derived summary we Limber-invert the power-law amplitude to obtain \(r_0=6.18\pm1.13\) and \(5.59\pm1.02~h^{-1}\mathrm{Mpc}\) for the AGN and TOTAL priors, respectively. These results establish MeerKLASS UHF DR1 as a new wide-area, intermediate-frequency dataset for radio-continuum clustering. As MeerKLASS expands and overlapping optical/IR spectroscopy provides improved redshift calibration, future releases will enable population-split clustering and bias evolution measurements with substantially reduced modelling uncertainty.

In this study, we numerically investigate Bondi-Hoyle-Lyttleton (BHL) accretion around Kerr-Sen black holes and examine how the charge-related deformation of the spacetime affects the shock-cone morphology, the variation of the mass accretion rate, and the quasi-periodic oscillation (QPO)-like temporal behavior. The relativistic BHL flow is solved numerically in the equatorial plane for two different black hole spin parameters, a = 0.9 M and a = 0.5 M. From the numerically computed mass accretion rate signal, we calculate the power spectral density (PSD) and perform multi-component Lorentzian fits to identify the dominant QPO-like modes excited around the black hole. The results show that the Kerr-Sen deformation shifts the characteristic frequencies, changes the coherence properties of the oscillation modes, and produces near-resonant harmonic structures close to 3:2 and 2:1. By using inverse mass scaling, the numerically computed frequencies are compared with observed QPOs from stellar-mass, intermediate-mass, and supermassive black hole systems. In particular, reasonable agreement between the numerical simulation results and observations is found for the sources GRS 1915+105, IGR J17091-3624, M82 X-1, NGC 5408 X-1, RE J1034+396, 1H 0707-495, and ESO 113-G010. This comparative analysis indicates that Kerr-Sen black hole shock-cone oscillations may provide a unified framework for interpreting timing features over a broad range of black hole masses and may additionally contribute to constraining the mass and spin parameters of sources whose properties are not yet fully established observationally. These findings further imply that combined hydrodynamical and timing diagnostics constitute a promising approach for assessing the extent to which deviations associated with the Kerr-Sen geometry can be empirically distinguished from those of the Kerr spacetime.

Magnetic fields are ubiquitous in the universe. They play a key role in shaping the activity of stars, the habitability of rocky planets, and the long-term retention of planetary atmospheres. Theoretical scaling laws are largely constrained by the limited set of stars and Solar System planets, leading to a wide range of possible values for hot giant planets outside of the Solar System from fractions of the Jovian field to orders of magnitude larger. Ultra-hot Jupiters, with their highly ionised atmospheres, provide a new avenue to probe magnetic effects, as their atmospheric circulation could be directly sensitive to atmospheric magnetic field strength. Using high-spectral resolution observations targeting the iron lines of ultra-hot Jupiters we measure the Doppler shift and thus the wind speed of seven transiting ultra-hot Jupiters. We find a clear decrease of wind speed with increasing planetary temperature, a trend inconsistent with purely hydrodynamic mechanisms but naturally reproduced by magnetic drag. From this relation we estimate the possible strength of magnetic fields of hot giant planets to at most a few gauss - comparable to the Jovian equatorial field. Our results support the idea that magnetic fields affect the atmospheric circulation of ultra-hot Jupiters and could provide a crucial benchmark for scaling laws used to predict magnetic fields in exoplanets, from hot Jupiters to rocky Earths with additional implications for future direct observations.

To advance our understanding of dust properties in class 0/I young stellar objects, it is crucial to resolve their structures at multiple wavelengths and investigate how grain growth and environmental effects shape their spectral properties. We present 0.5 arcsec resolution ALMA observations of the GSS 30 complex at 1.2-3.0 mm from the FAUST large programme, achieving a linear resolution of 69 au. We analyse the dust continuum emission and perform modelling to constrain dust properties and disk structures. For IRS3, the spectral index increases radially from 2.0 at the centre to 2.5 at the disk edge, while decreasing to 1.6-1.8 along the outflow direction. The asymmetric low-alpha region towards the northeastern blueshifted lobe may result from cold outer envelope dust obscuring warmer inner regions. SED fitting suggests maximum grain sizes of tens of microns and a dust mass of 650-1510 M_earth. IRS1 is associated with an extended north-eastern structure, which may represent an outflow-disk complex, a trailing structure linked to a circumbinary disk, or a gas streamer accreting onto IRS1. The central IRS1 shows alpha < 0.8, consistent with marginally optically thick free-free emission. IRS2 displays brightness variations over 420 s, and multi-epoch comparison suggests a flare lasting tens of minutes, likely caused by magnetic activity in the protostar. Our results highlight the importance of environmental effects, including dust obscuration and streamer structures, in shaping the observed properties of young disks, and reveal millimetre variability associated with possible protostellar magnetic flares.

Convection in icy moon oceans is strongly influenced by rotation, organizing into slantwise columnar structures aligned with the planetary rotation axis. They generate significant meridional heat transport, which can affect the ice shell topography, a primary observable of these moons. However, global ocean simulations cannot resolve convection under realistic icy moon conditions, and traditional convection schemes cannot represent slantwise convection. Here, we develop a slantwise convection scheme and implement it in a global ocean model. We perform benchmark tests in a global spherical shell by comparing parameterized fluxes with convection-resolving simulations. The scheme reproduces the meridional heat transport inside the tangent cylinder, where slantwise convection dominates. The resulting meridional heat transport significantly modifies the surface heat flux, producing variations comparable to the imposed bottom heating magnitude. Although the simulations with parameterized convection cannot fully reproduce the temperature structure, likely due to an inability to reproduce the temperature gradients near the boundaries, they capture the bulk interior vertical temperature gradient. The new scheme allows unresolved slantwise convection to be represented in global ocean simulations for icy moons. It is also applicable to other rapidly rotating oceans with small natural Rossby number ($\mathrm{Ro}^* \ll 1$), including deep ocean worlds on exoplanets.

We investigate whether embedded stellar-mass black holes (sBHs) in active galactic nucleus (AGN) disks can leave observable optical/UV variability signatures through migration-trap-driven magnetic heating. This mechanism operates when sBHs migrating toward torque-balance radii pile up near migration traps, triggering localized, stochastic magnetic reconnection that heats the disk atmosphere. It is potentially important because it provides a physical source of non-coronal disk heating and directly links optical/UV continuum variability to otherwise hidden compact-object populations. By coupling a one-dimensional sBH population synthesis model with a corona-heated accretion-disk reprocessing variability framework, we show that migration traps concentrate sBHs at preferred radii and generate localized, stochastic reconnection heating. The resulting heating is self-regulated: sBH pile-ups enhance the reconnection rate, while gap opening reduces the local gas density and partially suppresses the reconnection power. This heating produces excess short-timescale optical/UV variability, flattened short-term structure functions, and deviations from the standard $\tau\propto\lambda^{4/3}$ lag-wavelength relation, which describes the time delay between variability at different wavelengths for a standard thin accretion disk. These signatures are strongest at low-to-moderate Eddington ratios, and related observations could provide indirect evidence for embedded compact-object populations in AGN disks.

We present an investigation of the Tully-Fisher (TF) relation solely for galaxies hosting an active galactic nucleus (AGN). Using 22 galaxies with primary, z-independent distances, we find that active galaxies exhibit significantly larger scatter about all TF relations compared to each respective calibration for (largely) inactive galaxies. The larger scatter persists despite removal of the AGN contamination from the photometry of the Type 1 AGNs via 1) careful surface brightness decompositions or 2) employing SEDs to constrain the light contribution of the AGN. These results suggest that the influence of an AGN on its host galaxy's surface brightness may extend beyond the nucleus. We also calculate the percentage difference between TF and primary distances, and find that TF-based distances are biased towards overestimation of the primary distances to active galaxies by anywhere from 5-10 percent for the optical/near-infrared and approximately 15 percent for distances predicted from inverting the Baryonic TF (BTF) relation. As TF-based distances (especially the I-band) are relied on heavily for analysis and modeling of the local peculiar velocity (Vpec) field, we suggest that active galaxies be removed from future Vpec modeling samples.

We present a study of two tailed radio galaxies in the core of a massive, dynamically young galaxy group - an early group-group merger. Using VLA (3 GHz and 1.4 GHz), MeerKAT (1.35 GHz), and GMRT (610 and 325 MHz) observations, we investigate their radio spectral properties, spectral and dynamical ages. Radio morphologies show clear evidence of interaction with the intragroup medium (IGM). One galaxy is a wide-angle tail (WAT) source, while the other is most likely a head-tail (HT) galaxy. Both galaxies exhibit high radio luminosities, and we find spectral indices of $\alpha=0.8\pm 0.1$ (WAT) and $\alpha=0.6\pm 0.2$ (HT). Spectral index analysis reveals spectral steepening with distance from the core in both galaxies, with localized flattening in the WAT lobes and hotspots along the northern jet, and indications of such flattening in the middle of the HT tail. Spectral ages derived using Jaffe-Perola model are $33.80\substack{+7.63 \\ -7.23}$ Myr (WAT) and $20.86\substack{+10.07 \\ -17.17}$ Myr (HT), significantly lower than dynamical ages of $420\pm60$ to $700\pm100$ Myr (WAT) and $140\pm20$ Myr (and possibly up to $280\pm40$ Myr, for HT), yielding dynamical-to-spectral age ratios of $\sim12-20$ and $\sim7$ (and up to $\sim14$), respectively. The discrepancy may be reduced by using more complex dynamical age models, incorporating interactions with the IGM, which requires deeper X-ray observations of the group. Spectral age estimates may be affected by mixing of electron populations, and could be better constrained with future deep, high-resolution broad-band radio observations at both MHz and frequencies above 3 GHz. The combination of extended radio structures, spectral signatures of radiative aging with localized re-acceleration, and activity timescales up to hundreds of Myr indicates that galaxies are actively interacting with, and likely depositing energy into their environment.

We present a unified, multi-scale study of non-Gaussianity of Galactic foreground emissions using Minkowski Functionals and generalized skewness-kurtosis parameters, focusing on the characterization of small-scale non-Gaussianity and its underlying physical origin. We find that all foreground components studied exhibit a remarkably universal non-Gaussian nature dominated by excess kurtosis, whose shape remains stable across angular scales despite large differences in emission physics. Focusing on thermal dust, we perform a detailed comparison between observed maps (GNILC and Planck 545 GHz) and dust model realizations (PySM and filament-based models) to assess the performance of state-of-the-art models in reproducing the observed non-Gaussian properties. At the global level, GNILC and PySM display closely matched kurtosis behavior over the angular scales where the GNILC reconstruction is reliable, while the filament-based model produces substantially weaker skewness and kurtosis signals. For PySM, however, a patch-based analysis reveals statistically significant regional variations, indicating that while the model reproduces the overall non-Gaussian amplitude and scale dependence, it does not fully capture the spatial variability of the observed kurtosis signal. Using simple PDF-based toy models, we demonstrate that the universal kurtosis signature arises from the combination of heavy-tailed one-point statistics and steep large-scale spatial correlations, while its detailed amplitude and scale dependence depend on the underlying foreground physics. These results identify excess kurtosis as a robust statistical fingerprint of Galactic foregrounds and provide a practical framework for validating small-scale foreground models for future CMB analyses.

Luminous red novae are astrophysical transients associated with unstable mass transfer in interacting binaries and are commonly interpreted as outcomes of common-envelope evolution, possibly ending in merger. These interactions can liberate large amounts of gas, part of which may later condense into dust. We study the luminous red novae AT2021biy and AT2021blu to constrain their binary progenitors, estimate the mass ejected during the outbursts, and infer the dust mass from the infrared evolution of their remnants. We computed two grids of binary stellar-evolution tracks with the MESA binary module, constrained by pre-outburst photometry. We applied mass-transfer instability criteria to select progenitors able to merge on timescales compatible with archival observations. From these models, we estimated the gas mass lost during the mass-transfer phase and lower and upper bounds on the envelope mass that could be ejected during common-envelope evolution using the available orbital energy. We compared these ejecta-mass estimates with values inferred from light-curve models. Finally, we modeled mid-infrared NEOWISE data to derive dust masses up to ~3 years post-outburst, providing an additional lower limit on the total ejecta mass. We constrained the donor masses to Md = 18-23 Msun for AT2021biy and Md = 14 +/- 0.5 Msun for AT2021blu. Lower limits on the ejected envelope mass are 0.03-2.98 Msun for AT2021biy and 0.02-0.1 Msun for AT2021blu. Comparison with light-curve models favors intermediate mass ratios, q = 3-10 for AT2021biy and q = 5-15 for AT2021blu. The inferred dust masses are 1-5 orders of magnitude below the estimated ejected envelope masses, implying that only a small fraction of the gas condenses into dust. Their evolution is consistent with shock interaction and suggests pre-existing circumstellar material, in line with the pre-outburst mass loss predicted by our MESA models.

Recent models of pulsar polarization predict that the position and ellipticity angles of the polarization vector can trace portions of a small or great circle on the Poincare sphere. A great circle can arise from a transition in dominance of orthogonal polarization modes, where the relative intensity of the modes changes with pulse longitude. A small circle may be caused by a rotation of the vector, where the phase difference between the modes changes with pulse longitude or wavelength. Observations of PSRs B1133+16 and B2016+28 are reanalyzed to search for these polarization features within their pulse profiles. The polarization angles observed in part of PSR B1133+16 are shown to follow a great circle on the Poincare sphere. The angles observed across the pulse of PSR B2016+28 follow an arc that resembles a portion of a great circle that has been altered by the pulsar's rotation. The observations are interpreted within the context of three different polarization models. All three models produce similar results for both pulsars and indicate that the observed geodesics are caused by mode transitions. The arc observed in PSR B2016+28 can also be interpreted as a vector rotation, provided the modes are elliptically polarized. The observations and accompanying analysis show that mode transitions are not restricted to the equatorial plane of the Poincare sphere and that arcs and partial circles may be more common than previously recognized.

We present a numerical implementation of dissipative relativistic magnetohydrodynamics based on Bemfica-Disconzi-Noronha-Kovtun (BDNK) theory, in which first-order corrections render the equations causal without introducing additional dynamical variables. We show how these corrections can be incorporated in a finite-volume scheme describing the coupled dissipation of energy, momentum, and magnetic field, with the latter treated as a one-form charge. While a minimal set of BDNK terms can convert diffusive equations into telegrapher-type equations, we find that in the ultra-relativistic limit an additional correction is required for the system to behave in a stable and causal manner. With this set of equations, we develop an efficient method for primitive-variable recovery and validate the implementation through an analytical benchmark and various two-dimensional simulations.

The Carruthers Geocorona Observatory is NASA's first mission dedicated to investigating the fundamental nature of Earth's exosphere. Its primary payload, the GeoCoronal Imager, consists of two co-aligned broadband photometric imagers that support simultaneous, common-volume sensing of ultraviolet emission by exospheric hydrogen atoms. However, accurate parameter retrieval requires precise knowledge of the instrument's wavelength dependent responsivity. To that end, the mission aims to perform photometric measurement of stars and invert the observed fluxes to constrain the final passband. An objective, algorithm-driven ranking criterion identifies the best subset of stars to observe from a refined UV stellar spectral library tied to CALSPEC standards. The entire workflow - including the spectral library, passband inversion, and selection criterion - is validated using synthetically generated stellar measurements, which show that the proposed retrieval algorithm has high recovery fidelity, achieving passband error rates of <7% for both primary Lyman-alpha science channels.

We take advantage of the state-of-the-art semi-analytic model \texttt{FEGA25} \citep{contini2025}, run on merger trees extracted from three dark matter-only cosmological simulations, to study the relation between the black hole (BH) occupation fraction, $f_{\rm BH,occ}$, and galaxy stellar mass as a function of BH mass threshold, galaxy type, simulated volume, numerical resolution, sampled galaxy population, and redshift. \texttt{FEGA25} includes an improved treatment of active galactic nucleus feedback and does not impose a pre-existing BH seed population: BHs grow naturally through quasar and radio modes. Starting from the prerequisite that \texttt{FEGA25} reproduces the observed BH mass function from at least $z=2$ to the present day, our analysis leads to several results. We find that $f_{\rm BH,occ}$ increases with stellar mass, but that its normalization and shape depend strongly on the adopted BH mass threshold and on the relative contribution of central and satellite galaxies. The relative behavior of central and satellite galaxies depends on the simulation box and BH mass threshold, while the global relation should be interpreted as a population-weighted quantity. We also find significant box-to-box variations, reflecting the combined impact of numerical resolution, simulated volume, and sampled galaxy population. The redshift evolution is not universal: YS50 and the \texttt{NewCluster} zoom-in simulation show a trend qualitatively similar to that reported by \citet{tremmel2024}, whereas larger-volume boxes show the opposite behavior. Finally, comparison with other studies shows that the inferred occupation fraction is highly sensitive to BH mass threshold, simulated volume, numerical resolution, and sampled galaxy population.

Neutral hydrogen (H{\,\small I}) in the circumgalactic medium (CGM) and intergalactic medium (IGM) traces baryon cycling and galaxy evolution, yet fine filamentary substructures in diffuse CGM/IGM H{\,\small I} remain poorly constrained observationally. We combine FAST FEASTS single-dish and VLA THINGS interferometric H{\,\small I} data of the NGC 4631 group to report the first robust detection of kpc-scale filamentary structures in the CGM/IGM, with widths of $0.5$-$3.3\ \mathrm{kpc}$ and lengths of $6.1$-$49.8\ \mathrm{kpc}$. These features confirm that low-density CGM/IGM gas hosts velocity coherent substructure. From position-velocity kinematic analysis, we identify three filament classes (U-shaped, linear, and wavy), implying diverse formation mechanisms. Our results establish a structural bridge connecting pc-scale interstellar filaments, kpc-scale CGM/IGM filaments, and Mpc-scale cosmic-web filaments, providing key observational support for multiscale gaseous coupling in cosmic ecosystem.

Aims: We aim to quantify the metallicity dependence of the SBCR for red giant branch (RGB) stars and to test the robustness of the relation using asteroseismic radii, Gaia distances, and atmospheric parameters from APOGEE. Methods: We selected more than 2,000 RGB stars from APOKASC-3 to calibrate and validate the SBCR. Johnson V magnitudes were synthesized from Gaia XP spectra and homogenized to widely used SBCR photometric systems, while K_s photometry was taken from 2MASS. Angular diameters derived from asteroseismic radii and Gaia distances (ARD) were used to construct the SBCR. We explored three fitting strategies: metallicity-free, metallicity-binned, and global metallicity-dependent relations. Results: Over the range V-K_s=2-3, the SBCR shows only a weak metallicity dependence. A change of 1 dex in [Fe/H] modifies the predicted angular diameter by less than 1%, well below the intrinsic scatter of the calibration (~0.05 mag). This result is consistent with theoretical expectations. Comparison with the interferometric sample reveals a systematic offset of ~1.5% toward smaller angular diameters in our SBCR predictions, with a mild color dependence. Conclusions: The metallicity effect on the SBCR is small in the color range explored here, but it becomes relevant for sub-percent distance measurements. Our results show that large RGB samples with asteroseismic radii and Gaia distances provide a powerful observational route for SBCR calibration, with clear potential for extension to cooler and redder giants as the precision and parameter coverage of the input data improve.

OQ208 is a nearby, partially obscured quasar (z=0.077) that is a young, bright, parsec scale radio source. We assemble archival and new high frequency VLBA and VLA observations and optical spectra to form a data-set spanning 39 years. Radio light curves covering 58 years were also compiled. We utilize new spectrophotmetry to calibrate previous spectroscopy using forbidden narrow lines that are expected to be stable on much longer time scales. VLBA and VLA observations of a light-year scale bright nuclear flare at 15.4~GHz and 22~GHz reveal a rise (fade) beginning in mid-1996 (early-2000). Quasi-contemporaneously, from 2/7/1997-6/3/2000, the H$\alpha$ broad line equivalent widths (EWs) and fluxes dropped dramatically. In the context of the tendency of radio loud quasars to have a depressed extreme ultraviolet (EUV) continuum (the main source of ionizing flux for H$\alpha$) relative to radio quiet quasars at matched UV luminosity (the EUV deficit of radio loud quasars), this may not be a coincidence. Analytic models previously developed to explain the relationship between jet power and the EUV deficit are consistent with (but not direct observational proof of) the small EWs being a consequence of transient magnetically arrested accretion states from $\sim1997-2001$. The 22 GHz VLBA nucleus gradually fades, in 2023 the flux density is $<5\%$ of its value in 2000. The environs of the nucleus also fade at 22 GHz, but in a time delayed fashion.

Photometric classification of supernovae increasingly requires models that are not only accurate within a single survey but also robust to changes in cadence, noise properties, filter coverage, and survey domain. We investigate the generalization and domain stability of a compact 16-feature representation for Type Ia supernova classification. The feature set consists of physically interpretable descriptors of brightness, color, variability, and temporal evolution. Using the Supernova Photometric Classification Challenge (SPCC) dataset as the reference domain, we confirm that a compact XGBoost classifier achieves strong within-survey performance, reaching an F1 score of 0.844 and a PR-AUC of 0.928 on a held-out test set. We then evaluate robustness under alternative classifiers, repeated resampling, feature perturbations, missing-band proxies, shortened temporal coverage, and cross-survey transfer to PLAsTiCC. The compact representation remains stable under resampling and moderate perturbations, but direct SPCC$\rightarrow$PLAsTiCC transfer produces a substantial performance degradation. Class-conditional centroid analysis shows that the SPCC and PLAsTiCC Type Ia populations occupy different regions of the compact feature space. The cross-survey Ia centroid shift exceeds the Ia/non-Ia separation within either survey, indicating that the transfer gap is driven primarily by feature-space domain shift rather than classifier instability. These results show that compact physically interpretable features are robust within a survey and useful for diagnostic analysis, but are not automatically survey-invariant. Cross-survey deployment therefore requires feature harmonization, domain adaptation, or restriction to a smaller set of survey-stable features.

Near-IR spectra of a homogeneous sample of 15 red giants in the Galactic nuclear star cluster, within 1.5 pc of SgrA*, have been acquired with X-shooter at the Very Large Telescope. From these spectra line-of-sight radial velocities and chemical abundances of iron, carbon, oxygen and other alpha and light elements have been derived. By combining radial velocities from this study and proper motions from the literature we computed the orbits of these stars, finding that they have been confined within 12 pc from SgrA* for their entire lifetime, thus strongly suggesting an in-situ formation and evolution. Iron abundances between half and twice solar, about solar-scaled values within +/-0.1 dex for {\alpha} elements, Ti and V, some enhancement of [Na/Fe], [K/Fe] and [Al/Fe] and some depletion of [C/Fe] with respect to the solar ratios have been measured. The inferred chemical abundance distributions are consistent with a formation from a gas enriched by both type II and type I SNe over a prolonged timescale, closely matching those of the metal-rich populations of the inner bulge field and other complex stellar systems like Terzan 5 and Liller 1.

During a tidal disruption event (TDE), a star loses mass due to the tidal gravitational forces of the black hole. In a partial tidal disruption event, a stellar remnant is left behind. Several dozen TDEs have been detected so far, including repeating partial events. We use the Phantom smoothed particle hydrodynamics code to model the disruption of a 1 Msun star around a 10^6 Msun black hole for impact parameters resulting in less than equal to 50 % mass loss. We only consider zero energy orbits. Our simulations show that the mass fallback rate can exceed the Eddington limit for beta greater than or equal to 0.8, allowing debris to obscure the accretion disc by forming a reprocessing layer, similar to full TDEs. The mass fallback rate is shallower than t^{-5/3}, tracking closer to t^{-9/4}. Assuming thermal emission from the debris, that shock heating is trapped, that electron scattering dominates the opacity, and a color correction f_{col} of 1.7, we find temperatures of ~10^4 K, optical bolometric luminosities of ~ 10^{42-44} erg/s and blackbody radii ranging from 10-100 au for our simulations. We compare our values with observations and find support for the previous argument that some TDEs classified as full disruptions might actually be partial. Moreover, our results explain the detected optical/UV TDEs. We also find that our zero energy partial TDEs have properties similar to the repeating partial TDEs such as ASSASN-19dj, ASSASN-14ko, ASSASN-18ul, ASSASN-22ci, AT2020vdq and AT2022dbl. In the beta=0.8, isentropic simulation where radiation is assumed to escape, we find X-ray luminosities of ~ 10^{44-45} erg/s and radii lower than the inner most stable circular orbit.

Post-common-envelope binaries are the natural laboratories for constraining the physics of common envelope evolution, which is one of the most uncertain phases in binary stellar evolution. Traditional binary population synthesis models, adopting mass transfer stability criteria based on polytropic stellar models, systematically overpredict the number of post-common-envelope binaries with solar-type main-sequence companions. In this work, we present an updated binary population synthesis model using the rapid binary evolution code \textit{Binary Star Evolution}, incorporating a physically motivated mass transfer stability criterion and a self-consistent envelope binding energy prescription. We compile a comprehensive sample of classic white dwarf + main sequence post-common-envelope binaries with well-measured parameters, hosting both M-dwarf and A/F/G/K- stars. We find that the enhanced mass transfer stability is an additional mechanism responsible for the observed dearth of post-common-envelope binaries with solar-type main sequence companions; neither magnetic braking nor selection effects alone can fully account for this deficit, and a combination of all three processes is most likely required. Models with inefficient common envelope evolution ($\alpha_{\rm CE}=0.25$) provide the best overall match to the observed population. These results highlight the critical role of MT stability in shaping the observed post-common-envelope binaries population and provide new constraints on common envelope evolution.

The upcoming launch of the PLATO mission will open a new area of exoplanetary research by probing transiting exoplanets at long orbital periods around bright stars. These planets will be amenable to follow-up observations, especially with the ESO telescopes as the first PLATO field is in the southern sky. In this paper we listed the lessons we learned by monitoring the bright HIP41378 multi-planetary system over one decade via both radial-velocity and transit observations. These lessons are important for the follow-up strategy of PLATO transiting exoplanets.

The assembly history of the central regions of disc galaxies is regulated by dynamical processes that trigger gas infall events, leading to active star formation in nuclear stellar discs (NSD) and in nuclear stellar clusters (NSC). In the Milky Way, recent studies of its nuclear regions have revealed a complex star formation history (SFH), with an initial burst associated to the formation of the Galactic bar, followed by a non-constant star formation rate. In this work, we aim to study the formation and evolution of nuclear structures and their link with the formation of large-scale structures. Our goal is to investigate the effects of the bar and spiral arms on the gas dynamics and, as a result on the SFH of NSDs and NSCs. We run a simulation of an isolated Milky Way-like galaxy with the SWIFT N-Body+hydro simulation code, including star formation and stellar feedback from SNIa & SNII. We start from a live DM halo and a pre-existing stellar & gaseous disc with 20% gas fraction, which form a bar, a boxy/peanut bulge, spiral arms and nuclear structures. We study the SFH of these regions and how they relate to variations in the bar length, strength and pattern speed. We investigate the role of spiral arms and their interaction with the bar. We find that the SFH of the nuclear regions display a main burst at bar formation time, due to bar-driven gas inflows. After bar formation, we find secondary periodic formation bursts, that do not appear in the disc SFH. These bursts occur when the spiral arms and the bar, rotating at different pattern speeds, reconnect, triggering secondary gas inflow events. The interaction of spiral arms and the galactic bar can enhance non-axisymmetric features in the disc, triggering bar-driven gas infall even after the bar has formed. These bar-spiral reconnection events are imprinted into the SFH of the NSCs and NSDs as episodic star formation bursts.

Cold collisionless matter is usually described by pressureless fluid equations; this fails in three-dimensional spherical geometry. For the cold spherical case, kinetic and fluid share the same time-domain dynamics, but in the spectrum the kinetic system admits one solution the fluid does not: a discrete mode at twice the central orbital frequency, $\omega_0 = 2\Omega(0)$. It is specific to 3D: razor-thin disks reduce to the fluid. Nonlinear simulations confirm it survives at finite dispersion. Around Sgr~A$^*$, it predicts $\delta\omega/\Omega \sim 10^{-4}$, set by the enclosed stellar mass, at the level GRAVITY probes.

Multi-planetary systems provide key constraints on planet formation and evolution, as their architecture encodes the dynamical history of planets formed within a common protoplanetary disk. However, the current population remains strongly biased toward compact, short-period systems, and only a limited number of such systems with measured masses and radii are known. HIP 41378 is an exceptional system hosting five transiting planets with orbital periods up to 1.5 years, including an ultra-low density planet HIP 41378 f. The outer transiting planets d and e remained poorly constrained with unknown periods and masses, leaving the system architecture only partially characterised. We present long-term monitoring of this target with high-precision radial-velocity (RV) instruments (HARPS, HARPS-N, HIRES, and ESPRESSO) and space-based photometry spanning 2015-2024. We detect RV signals for all the planets, confirming their orbital periods and constraining their masses. In particular, the RV data strongly favour an orbital period of Pd = 278 days for planet d and refine the orbital period of planet e to Pe = 393+3-5 days. We measure a new mass of Mf = 25 \pm 5 earth masses for HIP 41378 f, confirming its super-puff nature with a bulk density of 0.166+0.033-0.036 g cm3. We also confirm the planetary nature of HIP 41378 g, a non-transiting planet with a 63-day period, and determine its minimum mass. In addition, the RVs reveal a long-period signal, with P = 2602+468-433 days, which we attribute to the candidate planet HIP 41378 h, although a stellar magnetic cycle cannot be excluded. Finally, we investigate the system's dynamical architecture and resonant structure, assess its completeness by constraining additional undetected planets, and discuss the implications for the origin and internal structure of the remarkable planet HIP 41378 f.

We report the RAD@home citizen science discovery of a unique bow-and-arrow-shaped radio galaxy (BAARG; RAD J104501.6+352852, z = 0.159) identified in LoTSS DR2. The source exhibits striking asymmetry: on the western side, a narrow jet feeds a sector-shaped emission region at ~115 kpc, extending backward to form a ~560 kpc arc-like structure; on the eastern side, the jet develops an S-shaped distortion extending to ~250 kpc, followed by a faint, offset tail reaching ~600 kpc. Our analysis shows that the host resides in a dynamically complex, multi-halo environment with nearby cluster-scale systems at similar redshifts. The observed morphology is consistent with interaction between the radio plasma and the surrounding medium, influenced by large-scale environmental gradients and bulk motions. The western structure is consistent with compression of radio plasma near a bow-shock-like feature, possibly linked to supersonic motion of the infalling host galaxy and its circumgalactic medium. This possibly represents one of the first instances in which morphology and environment together suggest signatures of infall- or shock-related processes; surveys such as LoTSS DR3 may reveal similar systems, offering new insights into the interplay between radio galaxies and their large-scale environments.

We study the motion of dust particles inspiraling from distant dust reservoirs toward a close-in planetary system, including the combined effects of radiation pressure and Poynting-Robertson (PR) drag. As dust particles migrate inward, they can be trapped in mean motion resonances (MMRs) depending on the competition between the planet's gravity and PR drag. Our goals are to understand the conditions under which particles can be trapped in MMRs, the evolution in and eventual escape from resonance, and the fraction of dust particles which will hit the planetary upper atmosphere, seeding it with heavy elements. Low-order eccentricity expansions of the disturbing function break down, so we employ an exact, rapid-phase--averaged disturbing function to determine resonant equilibrium points and their stability. We derive analytic expressions for the growth rate of dissipative equilibrium points and confirm that librations are generically overstable in important low-order resonances such as $3\!:\!1$, $2\!:\!1$, and $3\!:\!2$, implying that resonant capture is ultimately temporary and dust particles escape over a wide range of planet masses and dust size. After resonance escape, the dust orbit is planet-crossing and its subsequent evolution is intrinsically stochastic, governed by repeated close encounters that produce random gravitational kicks. We develop an analytic, epicycle-based scattering model to derive the impact parameter distribution $P(b)$ and the resulting energy change distribution $P(\Delta x)$. Using these encounter distributions, we construct a Monte Carlo method that predicts the fractions of dust particles that collide with the planet, sublimate near the star, or are ejected. Comparison of the Monte Carlo calculations with orbit integrations shows good agreement across the cases studied.

We present a spectral analysis of the NuSTAR and NICER observations of the accreting millisecond X-ray pulsar IGR J17062-6143, performed in 2022. The source remained in the hard spectral state during the observations, with a luminosity of about 0.2-1.3$\%$ of the Eddington luminosity. The continuum emission of the NuSTAR spectrum is entirely dominated by a power-law component or by Comptonized emission of disk photons by a plasma with a high electron temperature ($\gtrsim100$ keV). The NuSTAR spectrum also reveals clear evidence of disk reflection, a broad Fe K line around 6-8 keV, and a Compton hump peaking at 20 keV, irrespective of the choice of the continuum models. Our spectral studies suggest a disk extending close to the neutron star surface ($\sim$7-17 $R_{\rm g}$) at low inclination angles ($\sim$20$^\circ$-40$^\circ$), as revealed by a couple of self-consistent relativistic reflection models, relxill and relxillCP. In addition, we detected type-II bursts for the first time in the NICER observation of this source. Light curve profiles of type-II bursts exhibit different patterns, mostly associated with the so-called mode-0 and mode-1 type-II bursts. The energy spectra of the persistent (pre-burst) and burst emission are well described by an absorbed Comptonization component, scattering diskbb- and blackbody-distributed photons, respectively, by a corona with a temperature of 1-3 keV. Although the origin of the type-II burst is not very clear, it has been substantially linked to magnetospheric gating of the accretion flow.

Terrestrial planets likely experienced one or more giant impacts during their formation that inflicted large thermal, chemical, and rotational perturbations. The early states of terrestrial planets are expected to be dominated by the thermal and rotational outcomes of giant impacts, but critical parameters that control internal processes, such as the pressures and temperatures of core formation, are not fully understood. Here we present the results from a representative suite of collisions between Moon- to super-Earth-mass bodies using the SWIFT hydrocode and updated ANEOS equations of state, allowing more robust temperature calculations. Using these results and the HERCULES planetary structure code, we calculated the contributions from thermal energy, gravitational potential energy, and post-impact rotation on the pressure-temperature conditions of the core-mantle boundary (CMB). We derived scaling laws for the efficiency of impact heating, mantle-core heat partitioning, and CMB pressures and temperatures. We find that post-impact CMB pressures are generally lower than previously assumed, due to both thermal and rotational effects. Full mantle melting is common and a substantial fraction of mantle material is heated above the Fe-MgO solvus closure temperature for impacts with modified specific energies $Q_S>10^6$ J/kg, implying that a miscible layer could form close to the CMB for many giant impacts. The comparatively low internal pressures and large regions of metal-silicate miscibility after giant impacts have significant effects on the processes of core formation, and our work indicates that metal-silicate equilibration would occur near the CMB during later post-impact cooling, consistent with Earth's geochemistry.

We present detailed model diffuse continuum (DC) plus hydrogen emission line templates from a summation over a broad range in hydrogen gas densities. We address the effect of finite gas densities and the presence of weak higher-order emission-line transitions on the strength and location of the Balmer and Paschen jumps which act to shift the jumps red-ward of their respective vacuum wavelength positions and substantially soften the gradient of the jump. Our photoionisation model-based DC template favours a lower optical depth and lower electron temperature than traditionally employed for the Balmer continuum, directly impacting empirical estimates of the strength of UV FeII. Microturbulent velocities increase the emission-line -- continuum contrast, suppressing the DC contribution and weakening the jump heights, though the spectral shape of the DC remains broadly similar. Even with these additional complexities, a spectral decomposition of the UV-Optical-IR spectrum of the NLS1 Mrk 110, which includes a substantial DC contribution (30-50% of the total light at 3600A), reveals a significant deficit in emission just longward of the Balmer jump. Interestingly, significant thermal DC emission acts to flatten the SED through the UV-optical, negating oft-employed intrinsic reddening. Our best fit 1000A - 3 micron model requires a black hole mass of $~10^{8}$ Msun, similar to that inferred when considering features in the H/He broad emission line profiles, that suggest the presence of gravitational redshift. Finally, we provide diagnostic plots that may assist the spectral modeler to construct a physically useful DC spectrum and quantify its contribution to AGN UV-optical spectra.

One of the current challenges in observational cosmology is obtaining high-precision polarisation maps of the CMB to measure primordial $B$-modes and constrain the tensor-to-scalar ratio ($r$). The weakness of this signal compared to foregrounds and $E$-to-$B$ leakage makes this task particularly challenging, requiring large detector arrays operating at multiple frequencies and extremely precise calibration. We present a cross-calibration algorithm to determine relative calibration of detectors within the same frequency band of a CMB experiment. The method iteratively compares single-detector maps with band-averaged maps and can be applied to any calibration parameter that can be observed and corrected at the map level, relaxing pre-flight calibration requirements and enabling post-processing validation. We validate the pipeline by calibrating the polarisation angle of simulated LiteBIRD observations, including both random detector miscalibration and wafer-level rotations. The algorithm converges to correct values with arcminute precision. Finally, we propagate residual calibration uncertainties through component separation and tensor-to-scalar ratio estimation pipelines using both parametric (FgBuster) and blind (HILC) methods. The induced bias on $r$ remains well below the LiteBIRD systematics budget of $\delta r < 6.5\times10^{-6}$, demonstrating that the method is suitable for next-generation CMB experiments.

High-resolution thermal emission spectroscopy provides a powerful probe of atmospheric circulation in ultra-hot Jupiters (UHJs), with Doppler shifts encoding information about the 3D wind field across the planet disk. Retrieving these wind properties from phase-dependent emission spectra requires a forward model that is both physically motivated and computationally tractable. We present dopplerkernel, a new forward model that parametrizes the projected line-of-sight velocity field on the planet disk using four wind parameters (an equatorial jet speed $v_\mathrm{jet}$ and width $\sigma_\mathrm{jet}$, a source-to-sink flow speed $v_\mathrm{wind}$, and a flow convergence longitude $\varphi_\mathrm{sink}$) and constructs a broadening kernel via weighted kernel-density estimation. We apply this framework in a Bayesian retrieval to synthetic $K$-band emission spectra of WASP-76b generated from three 3D GCM outputs. Our retrievals successfully recover the equatorial jet in the drag-free GCM to within ${\sim}1$ km/s of the zonal mean and infer day-to-night wind speeds in good agreement with GCM averages at 1-10 mbar for all three drag regimes. We find that spectral resolutions of $R \sim 100{,}000$ offer an optimal trade-off: sufficient to resolve global wind features while avoiding spurious detections caused by model-data mismatches at higher resolution. Combining pre- and post-eclipse phases yields more reliable constraints than either alone, particularly on the orientation of the source-to-sink flow. Experiments with more complex weight functions reveal a degeneracy between the velocity field and the thermal weighting, cautioning against overparametrization. In conclusion, a parametric broadening-kernel model with a small number of physically interpretable parameters can accurately reproduce the phase-dependent line shifts, shapes, and strengths in UHJ emission spectra.

We present a spatially resolved archaeological reconstruction of the Sextans dwarf spheroidal (dSph) galaxy using deep DECam wide-field photometry and the PANCAKE CMD-fitting code. By analyzing the star formation history (SFH) and age-metallicity relationship (AMR) across four radial zones, namely: core, ring, outer body, and outskirts, we find that Sextans is a composite system formed through a minor merger approximately 13 Gyr ago. Our results reveal an inverse metallicity gradient: a primitive, metal-poor host (the current core) surrounded by a more massive, chemically evolved envelope ($\Delta$[Fe/H] $\approx$ -0.5 dex) introduced by the accreted satellite. We identify a distinct delayed onset of star formation in the ring at $\sim$ 13 Gyr, marking the merger event. While the core quenched early, star formation in the outer body and ring persisted until $\sim$9 Gyr, suggesting that the final cessation of activity was driven by environmental stripping during infall into the Milky Way halo. We propose a plausible scenario to reconcile the derived inverse metallicity gradient with the observed horizontal-branch (HB) morphology and reported Mg deficits. We suggest that the red HB dominance in the core reflects its ancient, $\alpha$-rich nature, while the blue HB in the outskirts represents an $\alpha$-poor, accreted component. However, we note that our CMD-derived [Fe/H] values are model-dependent inferences based on the total metal content $Z$. These findings suggest a non-monolithic assembly for Sextans, posing a testable prediction of a strong radial gradient in [$\alpha$/Fe].

X-ray absorption variability in active galactic nuclei (AGN) provides key constraints on the structure and dynamics of the circumnuclear obscuring medium, the so-called torus. A fraction of nearby AGN, however, have been classified as non-variable in line-of-sight (LoS) column density based on limited temporal coverage. We present the first systematic study of a sample of 11 local (z $\leq$ 0.1) obscured (N$_{\rm H} \geq 10^{22}$ cm$^{-2}$) AGN, initially classified as non-variable. The sample is selected from the Swift-BAT 100-month catalog, and comprises 60 observations from Chandra, XMM-Newton, and NuSTAR, spanning timescales from days to nearly two decades. We simultaneously model all available spectra for each source adopting physically motivated torus models: X-skirtor, RXTorusD, and UXCLUMPY. This approach allows us to derive the global properties of the obscurer while tracking possible epoch-to-epoch variations in the LoS column density and intrinsic X-ray emission. We find that the original non-variable classification (based on only two X-ray observations) is frequently not robust: clear N$_{\rm H,LoS}$ variability is detected in half of the sample, whereas 7 out of 10 AGN require intrinsic flux variability, with the rest showing flux-N$_{\rm H,LoS}$ degeneracies. We also find that the probability of identifying absorption variability increases with the number of observations, and the largest column density changes preferentially occur on long timescales, consistent with absorption by extended, structured clouds on torus scales. These findings support a clumpy and dynamic obscuring medium as a common feature of nearby AGN and highlight the importance of long-term X-ray monitoring for accurately characterizing AGN obscuration.

In this work, we investigate the features present in the joint primary mass and effective spin distribution of binary black holes without relying on specific modelling assumptions. We make use of non-parametric methods, flexible models capable of approximating arbitrary probability densities with minimal mathematical assumptions, applying it to the newly released GWTC-5.0. Our analysis supports the presence of at least two separate sub-population of binary black holes showing different effective spin distributions: one of them, preferring positive $\chi_\mathrm{eff}$ values, points towards the direction of systems formed in a non-spherically-symmetric, dynamical environment.

Barnard's Star is the nearest single star to the Sun (1.8 pc), and hosts four recently-discovered planets. The star also has well-characterized stellar abundances of important rock-forming elements, including Fe, Mg, and Si. For refractory elements like these, the planets have likely inherited similar bulk elemental abundance ratios to the star, facilitating modelling of their interior structures. We present here an analysis of the Barnard's Star planetary system on several fronts. We perform a detailed stability analysis of the system, ascertaining that all four planets likely have masses between 0.19 and 0.84 $M_{\oplus}$, and are likely tidally locked, whereas a 4:3 mean-motion resonance chain for the inner three planets cannot be ruled out. Using atmospheric evolution models, we show that the prospect of extant primary atmospheres is highly unlikely on any of the planets. Barnard's Star's abnormally high Mg/Si ratio and low Th/Mg ratio imply planetary mantles which (a) are rich in (Mg,Fe)O ferropericlase; (b) have less than half the water capacity as Earth; (c) generate about half of the radiogenic heating as Earth; and (d) are cool and unlikely to have outgassed secondary atmospheres. Our analysis of this system presents an accessible set of first steps for the study of other nearby exoplanetary systems, as well as sub-Earth planets which will be increasingly discovered over the coming years.

The Dark Ages offer a uniquely clean window on primordial physics, making the redshifted 21-cm signal a promising probe of primordial non-Gaussianity (PNG). Forecasts for interferometric 21-cm measurements must account for foreground wedge avoidance, which removes a substantial fraction of Fourier modes, and this effect is especially severe at high redshifts. We develop a wedge-aware Fisher framework in which this mode loss is propagated directly into the variances of the cylindrical 21-cm power spectrum and reduced bispectrum. As a case study, we apply the method to forecast PNG constraints in two inflation models with different oscillatory features, a resonant model and a step model, for a lunar far-side array including thermal noise. Since these features affect both the power spectrum and the bispectrum, we apply wedge avoidance to both forecasts and compare their constraining power on PNG amplitudes in these oscillatory feature models. We find that wedge avoidance reduces available Fourier modes significantly in both observables, leading to much weaker constraints on PNG. This framework is broadly applicable to 21-cm power spectrum and bispectrum forecasts across redshifts and is particularly useful in regimes where foreground wedge effect is severe, such as the epoch of reionization and the higher-redshift Dark Ages.

Recent observations have revealed that the Milky Way is embedded in a massive circumgalactic medium (CGM) extending to several hundred kiloparsecs. Such an extended gaseous halo acts as both a reservoir of baryons and potentially as a confinement volume for Galactic cosmic rays (CRs). We investigate CR transport in this giant Galactic halo and compare its properties with those of conventional small-halo models. In the giant-halo scenario, the halo height is no longer a free parameter, but instead relates to the extent of the source region. We show that CR transport within the source region remains similar to that in small-halo models, while substantial differences emerge at larger distances. In the giant-halo scenario, CRs develop an extended approximately 1/r spatial tail and exhibit a broader age distribution than the small-halo case. This model is shown to be consistent with current secondary-to-primary CR measurements. We further find that uncertainties associated with Galactic gas distributions are comparable to those arising from nuclear spallation cross sections. These results suggest that the giant-halo model provides a physically motivated alternative to conventional small-halo models and may have important implications for diffuse gamma-ray and neutrino emission from the Galactic environment.

We perform a realistic KiDS-Legacy mock analysis with field-level neural compression and simulation-based inference using fewer than 100 $N$-body simulations. The weak lensing shear field encodes substantially more cosmological information than standard two-point summary statistics such as the power spectrum. Field-level inference can fully exploit this information, but physical realism at the field-level requires very high-fidelity simulations. This poses a major challenge for simulation-based inference (SBI): accurate empirical density modelling and deep-learning-based neural compression require many training simulations, but achieving physical realism at the field level makes each simulation extremely costly. We demonstrate that multifidelity SBI can alleviate this tension by substantially reducing the number of high-fidelity simulations needed for accurate cosmological inference. We pre-train neural inference models on realistic KiDS-Legacy-like shear mocks using fast log-normal GLASS simulations and fine-tune them on a small set of high-fidelity $N$-body simulations. We show that between $60$-$100$ high-fidelity simulations are sufficient to obtain informative and well-calibrated cosmological posteriors, enabling an order-of-magnitude reduction in simulation cost for accurate field-level inference in a realistic setting.

Emission lines that "echo" variations in the ionizing flux produced close to black holes are powerful probes of the central engine. In the Seyfert-1.5 galaxy NGC 4151, high-resolution X-ray spectra and time lags in low-resolution X-ray data suggest that part of the narrow Fe K$_{\alpha}$ line originates close to the optical broad line region (BLR). We report on a sequence of nine XRISM observations of NGC 4151, obtained every other day in 2024. Swift monitoring was undertaken to sample the driving flux before, during, and after the XRISM sequence. Using suitable line kernels, we measure a mean BLR component width of $\sigma = 5.36\pm 0.48\times 10^{3}~{\rm km}~ {\rm s}^{-1}$. Modeling the Swift continuum and XRISM line flux trends gives a lag of $\tau = 3.5^{+2.8}_{-1.7}$ days ($r=3.6^{+3.0}_{-1.7}\times 10^{3}~GM/c^{2}$ for $M_{BH} = 1.7\times 10^{7}~M_{\odot}$), significant at the $2\sigma$ level via Monte Carlo simulations, and consistent with prior measurements and direct spectral fits. This lag implies a black hole mass of $M_{BH}/f_{X} = 2.0^{+1.4}_{-1.0}\times 10^{7} M_{\odot}$, where $f_{X}$ is a geometrical factor. A standard optical value for this factor gives a mass that is nominally higher than typical H$\beta$ mass estimates, but formally consistent. Our results suggest that XRISM can measure lags and black hole masses in both unobscured and obscured AGN.

The carbon-enhanced metal-poor stars with hybrid enrichments of slow- and rapid neutron-capture elements, the so-called CEMP-rs stars, still raise many questions due to their elusive abundance signatures. In our recent analysis, we found that heavy r process elements are enhanced in these objects and can be explained by the intermediate neutron-capture process (i-process) occurring in low-mass, very low-metallicity asymptotic giant branch (AGB) stars. However, the origin of actinides such as thorium and uranium is typically associated with explosive nucleosynthesis in highly neutron-rich environments, and their detection in stellar spectra remains challenging due to severe line blending from other elements and carbon-bearing molecules. In this work, we investigate the presence of thorium and uranium abundances in a sample of CEMP-rs stars using their high-resolution spectra obtained with the UVES spectrograph mounted on the UT2 (Kueyen) ESO VLT. Thorium is robustly detected in three stars, while uranium remains marginally detected, allowing only upper limits to be derived. Comparison with theoretical i-process nucleosynthesis models demonstrates that the observed abundances can be reproduced within uncertainties, supporting an i-process origin for these elements. This study reports the first detection of actinides in stars confirmed as CEMP-rs stars, providing new constraints on their nucleosynthetic history. Furthermore, these detections provide a potential way to estimate in the future the time elapsed since the proton-ingestion episode in AGB stars using cosmochronometry techniques, and more generally to place lower limits on the ages of the resulting white dwarf remnants.

We present a survey of 24 Herbig Be stars (young stellar objects $>3$ M$_{\odot}$) within 3 kpc at 1.3~millimeters using the Submillimeter Array at about $1''$ resolution to identify circumstellar disks and assess planet forming potential. We detect 1.3 mm emission toward 5 Herbig Be stars that range in mass from 4.3 to 12.9 M$_{\odot}$. Follow-up observations at 0.87 mm show spectral indices consistent with partly optically thick dust emission. These millimeter detections are compatible with an extrapolation of the scaling relation derived for lower-mass T Tauri and Herbig Ae stars between millimeter luminosity and stellar host mass, and also millimeter continuum size, suggesting these detections represent emission from circumstellar disks. The implied disk masses are sufficient for giant planet formation. No decrease in the millimeter detection fraction with stellar host mass is evident within this sample that would implicate rapid disk dissipation by the radiation fields of the higher mass stars. The high fraction of millimeter non-detections is likely due to the survey sensitivity limits together with photoevaporation and the dynamical impact of stellar companions.

High-resolution spectroscopy observations of sunspots offer a unique natural laboratory for detailed molecular spectroscopy. Calcium monohydride (CaH) is a vital spectroscopic tracer in cool stellar and solar environments, where its electronic transitions are used for line identification and temperature diagnostics, yet its high-excitation transitions remain poorly characterized. Using high-resolution sunspot umbral spectra obtained with the Brault Fourier-transform spectrometer at the McMath-Pierce telescope (Wallace et al. 1999), we investigated the $A^2\Pi\;-\;X^2\Sigma^+$ electronic transition of CaH in the $\rm{14400-14900\;cm^{-1}}$ region. We report the assignment of 224 spectral lines spanning vibrational bands with $v^{\prime}, v^{\prime\prime} = 0\text{-}3$; notably, 75 lines in the (3-3) band are reported here for the first time, and the identification of the remaining bands was extended to significantly higher rotational quantum numbers ($J\rm{ _{max}\approx 49.5}$) compared to previous studies. Incorporating these new identifications into spectral simulations that account for overlapping TiO features, we aimed to reproduce the observed umbral spectrum and found modest but measurable improvement in the agreement between the simulated and observed spectra. Minimizing the residuals between observed and simulated spectra, we estimated an effective umbral temperature range of around 4000 K. We compare this effective temperature against those inferred from independent methods to show that molecular features primarily form in the cool umbral cores of the sunspots. This study demonstrates the utility of solar observations in studying the high-energy transitions that are challenging to reproduce in laboratory settings and the potential of molecular lines as sensitive "thermometers" for cool astronomical objects.

Convection remains one of the main uncertain links between multidimensional hydrodynamics and one-dimensional stellar evolution. In particular, transition regions such as near-surface layers or convective boundaries require mean-field descriptions that remain connected to the underlying dynamics rather than to a prescribed mixing length. We describe the flow as a distribution of mesoscopic fluid particles in position-velocity space. A conservation law for this distribution defines the average and yields the Reynolds-Favre mean-field equations as velocity-space moments. Under standard interior conditions, the same dynamics can be written in Liouvillian form, which extends the Hamiltonian structure to stratified and dissipative media. The Liouvillian formulation identifies the phase-space divergence, $\{s, T\}$, as a local measure of contraction or expansion of nearby trajectories. In the quasi-adiabatic limit, its sign reduces to the classical Schwarzschild stability criterion. Away from this limit, the diagnostic remains velocity-resolved and can distinguish different parts of the convective population within the same layer, for example in surface and penetration regions. Appendices show how rotation, magnetic fields, and composition changes can be incorporated through modifications of the phase-space structure. Phase-space averaging provides a dynamically grounded route from hydrodynamics to mean-field stellar convection equations. It also supplies a local trajectory-based stability diagnostic and a natural starting point for the maximum-entropy closures constructed in the companion paper.

Surface convection in cool stars sets the entropy jump between the atmosphere and the deep convective envelope, and therefore affects the radius and structure of one-dimensional stellar models. In standard local treatments, this entropy jump is controlled through an effective convective efficiency. We develop a phase-space closure that relates the mean stratification to the local distribution of entropy and velocity among convective elements. Our aim is to describe how the surface entropy transition emerges from the statistics of these elements, rather than prescribing it directly. We first construct a maximum-entropy model for the convective bulk, assuming that the realised states are bounded by a deep entropy level $S$. This maximum-entropy construction predicts a one-sided exponential entropy distribution, and its low-entropy tail is recovered in the deep convective part of the three-dimensional radiation-hydrodynamics simulations. Closer to the surface, the distribution is reorganised by radiative cooling and separates into two thermodynamic components. Using a radiative entropy branch, an adiabatically descending cooled branch, and a population fraction controlled by optical depth, the two-population closure reproduces the mean entropy stratification of the four reference simulations over most of the displayed range, without adjusting the entropy profile itself. The surface transition can therefore be interpreted as a continuous population decomposition, rather than as a sharp boundary between radiative and convective layers. This provides a natural route toward one-dimensional stellar models in which the surface entropy jump is determined from the statistical organisation of the flow instead of being set by a calibrated mixing-length efficiency.

We investigate the presence of high ionization fine-structure emission lines across a range of 22 OB-type stars observed with JWST-MIRI as part of calibration programmes and the WISCI and MEAD projects. MIR wind emission is detected in 4 late O-dwarfs (O8 V - O9 V), 1 early O-dwarf (O5 V) and there are tentative detections in an additional 3 stars (O8.5 II, O8.5 IV and O9 I). We measure the wind speeds and make estimates of lower limits on the mass-loss rates of 5 O-type stars from broad, flat-topped emission in the fine-structure line of [Ne V] 14.3micron. We find terminal wind speeds that are generally in agreement with empirical trends, but note that in some cases the wind speeds are surprisingly low. We highlight two main takeaways from this sample, which combine to establish an exciting new window into the winds of massive stars. First, a new diagnostic ability is gained from lines formed at much higher ionization, larger spatial extent, and longer wavelengths than typical wind diagnostics. Secondly, there is frequent incidence of MIR emission in O-type stars, even in the 'weak-wind' regime where wind emission is often not detected in the UV and optical.

We adapt the \textit{magnetohydrodynamic} wave phase-mixing paradigm [Tsiklauri et al. (2003)] to investigate \textit{acoustic} wave propagation and damping in media where transverse sound speed gradients exist. Using an analytical model, we recover previous harmonic wave and Gaussian pulse evolution solutions now controlled by the spatial gradient of the local \textit{sound speed}. We discover a scaling law governing a Harris current sheet-like pulse evolution: under developed-stage phase-mixing, the peak envelope of such pulse amplitude scales with propagation distance as a new power-law $\max(P_1) \propto x^{-9/2}$. Applying our model to the solar tachocline directly resolves the 26-year-old helioseismic mystery of low-$\ell$ global $p$-mode linewidth anomalies observed by BiSON above $\nu \approx 3000\,\mu\text{Hz}$. We demonstrate that the sound speed gradient forces rapid, non-turbulent energy damping directly in the shear zone, providing the exact high-efficiency bulk dissipation needed to account for the missing energy sink deep within the solar tacholine. Our model provides the exact damping rates that classical, homogeneous models severely underestimated in the past. Finally, our results provide actionable design strategies for engineering compact stealth coatings or meshes to achieve enhanced acoustic signature suppression from moving bodies immersed in a fluid.

We present new constraints on the mass and radius of the neutron star in the neutron star low-mass X-ray binary EXO 0748$-$676 obtained from a joint analysis of 20 quiescent X-ray observations obtained between 2008 and 2025, including 14 Chandra and 6 XMM-Newton exposures. These data sample two quiescent episodes separated by the 2024$-$2025 outburst. We model the 0.5$-$10 keV spectra with a hydrogen-atmosphere model, assuming a source distance of 7.1 kpc. In a global Markov Chain Monte Carlo analysis in which the hydrogen column density, neutron star mass, and radius are tied across all observations, we obtain a neutron-star mass of $1.77^{+0.17}_{-0.22}\,M_\odot$ and a radius of $12.62^{+0.56}_{-0.74}$ km ($1\sigma$ credible intervals). We further perform independent fits to the first and second quiescent epochs and find that the combined data set significantly reduces the low-mass tail in the posterior distribution, leading to tighter lower bounds on the neutron-star mass. Incorporating the distance uncertainty of $7.1\pm1.2$ kpc, we conservatively constrain the neutron-star mass and radius to $M\simeq 1.41-2.11~M_{\odot}$ and $R\simeq 10.15-15.13$ km, favoring relatively stiff dense-matter equations of state. We also trace the thermal evolution across two quiescent epochs and find evidence for renewed crust cooling following the 2024$-$2025 outburst, providing a unique opportunity to compare the thermal relaxation behavior after two distinct accretion episodes.

We model the LHAASO observation of diffuse TeV--PeV $\gamma$ rays in the Galactic plane as the sum of unresolved leptonic emission from pulsar wind nebulae and hadronic emission from supernova-injected cosmic-ray (CR) protons. We investigate uncertainties in the radial distribution of the infrared component of the interstellar radiation field (ISRF), using profiles with enhanced photon densities in the inner Galaxy. We quantify their effects on $\gamma\gamma$ attenuation of the diffuse $\gamma$-ray emission. The alternative ISRF models affect the LHAASO diffuse fit only modestly, as the analysis excludes the Galactic center direction and applies source masks in the Galactic plane. Using the hadronic normalization inferred from the LHAASO fit for various ISRF models, the associated $pp$ neutrino emission remains consistent with the IceCube all-sky measurement, while the flux from the Galactic Ridge region remains compatible with current ANTARES and KM3NeT constraints. Since the modified infrared profiles differ most strongly toward the inner Galaxy, we also examine their impact on inverse-Compton emission from point sources near the central molecular zone. These same models can noticeably modify the hadronic and inverse-Compton $\gamma$-ray emission above $\sim\!10$ TeV from sources in the central region. Future KM3NeT observations, combined with $\gamma$-ray measurements of individual sources, can probe the inner-Galaxy CR population and constrain the radial distribution of the ISRF near the Galactic Center.

Modeling circumstellar disks in the traditional sense carries the assumption that the dust density distribution can be accurately described with a fixed parametric form. Furthermore, commonly-used algorithms for subtracting the stellar point-spread function (PSF) distort the true morphology of the faint underlying disk structure, especially dusty features that are located at small angular separations. These phenomena often lead to significant residuals with parametric disk models and make it difficult to measure the full realizable range of the scattering function of the dust. We address these challenges with ffortissimo, a novel, pixel-based freeform forward modeling pipeline designed to characterize extended objects in KLIP-reduced images. We built this pipeline within the framework of JAX, which is a machine learning library in Python that enables efficient optimization through automatic differentiation ("autodiff") and GPU-accelerated array computations. Using visible light images of the disk around HR 4796A taken by the "extreme" Magellan Adaptive Optics instrument (MagAO-X), we show that our data-driven freeform models excel at fitting a complex dust distribution and can infer the dust scattering properties even through PSF subtraction artifacts. Additionally, we demonstrate the potential for retrieving spatial dust features beyond the diffraction limit of the telescope. We note that there are remaining challenges to address before precision photometry using these freeform models is advised. These include better background, wind-driven halo, and speckle characterization as preventing the freeform models from learning these noise artifacts is currently difficult.

We present total intensity images of the debris disk around HR 4796A from observations spanning 2023 to 2025 with the Magellan extreme adaptive optics instrument (MagAO-X). We detected the disk at high signal-to-noise ratios at $g' (527$ nm), $r' (615$ nm), $i' (762$ nm), and $z' (909 $ nm). Additionally, we present images collected using the "star-hopping" technique that show the entirety of the disk, including the dramatic forward-scattering at the minor axis. We subjected our images to a battery of modeling techniques to constrain the geometry and photometry of the disk. Leveraging our clear detections of the disk's minor axis, we modeled the scattering phase function (SPF) using a basis of the Legendre polynomials. To mitigate self-subtraction artifacts in our angular differential imaging, we implemented a forward-modeling pipeline that generates a pixel-based freeform disk forward model leading to a deconvolved image of the disk. Our best-fit disk models reveal: (1) highly forward-scattering SPFs with a minimum at the $\sim65^{\circ}$ scattering angle, (2) a faint halo of dust just exterior to the spine of the disk that is not well-described by a broken power law density profile, (3) a red spectral slope for the dust, and finally (4) a compact, clump-like feature in the freeform disk models. Our empirically-measured SPFs suggest that the scattering is dominated by large, highly-absorptive grains. However, we emphasize the need for testing advanced irregular grain models using our SPFs to learn more about the physical and chemical properties of this complex system.

The temporal morphology of flare light curves encodes the underlying flare physics, and deviations from the typical flare profile may indicate the presence of mechanisms not captured by a standard flare model. To search for such time-domain deviations from a "standard" flare, we develop an unsupervised Deep Support Vector Data Description (Deep SVDD) model, which learns a compact representation of normal flares, against which unseen anomalous flares are identified. The model is trained on synthetic light curves with a "normal" flare morphology, generated from existing analytical flare trend models with noise. Using the distribution of normal flare data, we introduce a probabilistic Flare Anomaly Index (FLAI) which allows for separating flare light curves into three distinct classes: normal data (ND), weak anomalies (WA), and strong anomalies (SA). Application of FLAI to the Kepler flare catalogue (white light) reveals that 36% and 30% of events belong to the WA and SA classes, respectively. For M- and X-class solar flares from the STIX flare list, 25% and 32% of events in the 15-25 keV channel are classified as WA and SA, respectively, versus 15% for both WA and SA classes in the 4-10 keV channel. Thus, anomalous flares appear more frequently in the STIX high-energy channel. These results show that both solar and stellar flares often deviate from the normal flare population used for model training, suggesting departures from the standard flare scenario, such as modified energy release and dissipation, or the development of wave and oscillatory processes in flare sites.

The surface of Mars is sterilized by ionizing radiation and pervasive oxidants; its shallow subsurface, shielded from ultraviolet light and the most reactive oxidation, may instead preserve habitable conditions. The radiolytic habitable zone (RHZ) hypothesis holds that galactic cosmic rays can drive water and oxychlorine radiolysis there, generating H2 and oxidants that support chemolithotrophy without sunlight or geothermal heat. We develop a quantitative framework coupling Monte Carlo GCR transport, phase-resolved radiolysis chemistry, water-activity and H2-retention treatments, and microbial maintenance-power constraints for Gale Crater, Oxia Planum, southern Utopia, and Arabia/Mawrth, expressing radiolytic chemical energy as a depth-resolved redox power comparable to the power requirements of life. H2 retention is the dominant control. Sorbed or mineral-associated retention yields 4-6 x 10^-13 W kg^-1 at protected depth (>=10 cm), whereas connected-pore free-gas escape lowers redox power by two to four orders of magnitude. Gale remains inactive under both retention assumptions, consistent with published SAM evolved-gas analyses. Even in retained-H2 active terrains, supported cell density reaches only 10^3-10^5 cells cm^-3 at subseafloor maintenance powers. The framework predicts a spatially restricted, low-density RHZ, testable by stepped H2 evolved-gas analysis of protected-depth samples from ExoMars Rosalind Franklin, Tianwen-3, or Mars Sample Return.

Based on 17.75 years of Fermi-LAT observations, we report a tentative double excess in the gamma-ray spectrum of the blazar 4FGL J0604.9-0000, with peak energies at approximately 1.5 GeV and 11 GeV. The two excesses are modeled as double Gaussian components. For the lower-energy excess, the best-fit centroid is $E_1 = 1.59\pm0.07$ GeV with a width fixed to the instrumental resolution ($\sigma_1 = 0.145$ GeV). For the higher-energy excess, the centroid is $E_2 = 11.15\pm0.61$ GeV and the width is constrained to $\sigma_2 = 1.185$ GeV (about 10\% of the peak energy), which is comparable to the Fermi-LAT energy resolution at that energy. The two features have local significances of $2.6\sigma$ and $3.7\sigma$ (3 dof), respectively. A joint likelihood analysis yields a combined test statistic of TS $\simeq 27$, corresponding to a local significance of approximately $4.3\sigma$ (4 dof, without correction for trials and the look-elsewhere effect) or about $4.8\sigma$ (2 dof). To our knowledge, no other active galactic nucleus has been reported to show a similar double-excess candidate. The observed energy ratio of $\sim$1:7 is difficult to explain with standard astrophysical emission processes. However, the energies and their ratio are consistent with dark matter annihilation (e.g., $\chi\chi\to\gamma\gamma$ and $\chi\chi\to\gamma\gamma'$) for a particle mass near 11 GeV, making this source a promising target for follow-up observations with next-generation gamma-ray telescopes.

Ultraluminous X-ray sources (ULXs) are among the best laboratories for studying super-Eddington accretion onto compact objects. We present a detailed spectral and timing analysis of the transient ULX NGC 4631 X-4 using archival Chandra, XMM-Newton, and Swift/XRT observations. The source exhibits pronounced spectral and flux variability on both short and long timescales, with luminosity variations exceeding two orders of magnitude. Its X-ray spectra are well described by absorbed multicolor disk blackbody and power-law models, with characteristic inner disk temperatures of 0.9-1.4 keV and photon indices of 2.0-2.4. The source does not follow the standard luminosity-temperature relation expected for a geometrically thin, optically thick accretion disk. No coherent pulsations or quasi-periodic oscillations are detected, while the short-term variability is dominated by aperiodic fluctuations and kilosecond peak-like structures, consistent with clumpy winds and geometric effects in a super-Eddington accretion flow. Overall, the spectral and timing properties support super-Eddington accretion onto a stellar-mass compact object, although the current data do not allow us to distinguish uniquely between a neutron star and a stellar-mass black hole accretor.

Warm inflation perturbations are sourced by both thermal and quantum fluctuations and are commonly computed through stochastic realizations of the perturbation equations, as implemented in the publicly available code SWIM. Deterministic formulations based on correlation matrix evolution provide a computationally efficient alternative, but can become numerically ill-conditioned when the perturbation variables evolve over widely different scales. In this work, we extend SWIM by introducing a deterministic module, DSWIM, based on correlation matrix evolution. We introduce a physically motivated scaling matrix transformation derived from the effective Hubble scaling of the perturbation variables. The transformed system preserves the primordial curvature power spectrum exactly while substantially improving the numerical conditioning of the deterministic evolution equations. Using representative warm inflation models, we show that the scaled framework suppresses numerical artifacts, improves the robustness of the deterministic evolution, and yields substantial computational speedups while preserving accuracy. We further show that correlated thermal noise contributions arise naturally through the diffusion matrix structure, resolving previously observed discrepancies between stochastic and deterministic implementations. Our results establish DSWIM as a numerically robust and computationally efficient framework for computing warm inflation scalar perturbations.

Characterizing long-period transiting exoplanets is inherently challenging due to the rarity and long duration of transit events. Yet, these systems provide unique insights into planetary formation, migration, the detection of exomoons, and primordial atmospheres by occupying a sparsely populated region of the exoplanet parameter space. The complexity increases further for long-period planets near mean-motion resonances, where transit timing variations (TTVs) can reach amplitudes of several hours to days. We present a coordinated space- and ground-based observing campaign, using photometry from NEOSSat, multiple LCOGT sites, MuSCAT, MuSCAT3, Tierras and NGTS, to capture the 19-hour transit of the long-period giant exoplanet HIP 41378 f ($P$ = 542 d, $R$ = 9.5 $R_{\oplus}$) on 31 October 2025. Our transit analysis constrains the time of inferior conjunction to $T_{\mathrm{C}} = 2460980.888 \pm 0.029~\mathrm{BJD_{TDB}}$, occurring $\sim 7$ hours earlier than predicted from its linear ephemeris. This significant offset is consistent with the previously reported TTVs of HIP 41378 f, making it the longest-period exoplanet known to exhibit measurable TTVs. By combining this new precise measurement to the transit timings of the two outer planets in the system (HIP 41378 d and HIP 41378 e), we perform a dynamical modeling of the system, using the N-body integrator TRADES, refine the ephemeris of HIP 41378 f, and predict future transit events for all three outer transiting planets.

In light of recent cosmological observations, we examine a generalized Chaplygin gas model with a redshift-dependent exponent as a framework for describing the dark energy and dark matter content of the Universe. Specifically, we treat this fluid as a single unified component and test it against late-time background observational data. We employ Type Ia supernova data, cosmic chronometers, and baryon acoustic oscillations from the second data release of the Dark Energy Spectroscopic Instrument. We perform a Bayesian analysis for parameter estimation and compare the model with $\Lambda$CDM. We find that the generalized Chaplygin gas provides systematically higher values of the combined likelihood; nevertheless, once the larger number of free parameters is taken into account, both the Bayesian evidence and the Akaike Information Criterion suggest that the model is statistically indistinguishable from $\Lambda$CDM.

One main theme of the Unification Model of active galactic nuclei is that there is an obscuring torus structure blocking the direct view of the central engine for Seyfert 2 galaxies. Here, we present the detection of long-term optical variability for a sample of nearby Seyfert 2s. We found that Seyfert 2s exhibit a relatively low but significant level of variability beyond the constant fluxes established by galaxies over month to year time scales. The variability is also detected in the structure functions of Seyfert 2s. Assuming a simple variability suppression model by the scattering region and dilution due to host starlight, where the region smooths the unobscured photon packets from the central engine as the light scatters over the torus, we estimate AGN scattering region sizes by matching the variability amplitudes of Seyfert 1s to 2s. Our measured scattering sizes are largely consistent with the torus size measured using their emission properties, suggesting that the scattering region is of a similar size as the torus. Our results pave the way towards variability as a powerful and independent test for AGN unification models.

Corotating Interaction Regions (CIRs) are persistent structures in stellar winds that arise from the interaction between fast and slow wind streams. They are known to generate shocks and high-energy particles, potentially influencing the erosion of planetary atmospheres and space weather conditions. Although extensively studied for the present-day Sun, their evolution over a star's lifetime and implications for planetary environments remain less explored. We model the evolution of CIRs around a solar-mass star using a rotational evolution framework and assess how their location, shape, and particle distributions vary with stellar age. We find that CIRs form closer to the star during early spin-up phases and migrate outward during spin down, with the minimum CIR radius inversely related to rotation rate. We show that the distribution of high-energy particles produced in CIR shocks varies significantly with age. During the Hadean period, when Earth's atmosphere evolved significantly, CIRs may have generated a number of energetic particles that is \(10^3\) to \(10^7\) times greater than for the present-day Sun. The frequency and strength of CIR-planet interactions also peak during early rapid rotation phases. Furthermore, we demonstrate from this preliminary study that, for stars with mass less than 1.4 Msun, whilst CIRs can form within the habitable zone, their shocks always form beyond it. This suggests that energetic particle impacts may rain inward from more distant regions, as with the present-day Sun. These findings have implications for habitability and the evolution of atmospheres since these particles can alter the chemistry and escape rate of atmospheres.

We present GBT-EDGE, a new CO(1-0) survey using the Green Bank Telescope to map 62 nearby (10-140 Mpc) galaxies spanning the star-forming main sequence (SFMS), green valley, and red sequence. The galaxy sample is selected from the CALIFA survey with integral field spectroscopy (IFS), which provides a representative census of local galactic environments. Combining the CO dataset with CALIFA's optical IFS measurements, we derive molecular gas masses, star formation rates (SFR), metallicities, and stellar mass densities to measure star formation efficiency (SFE) and investigate the physical drivers of galaxy quenching. We obtain a median molecular gas depletion time of $2.10^{+2.35}_{-1.31}$, $6.90^{+17.00}_{-3.67}$, and $127.7^{+201.6}_{-113.4}$ Gyr for our sample of main sequence, green valley, and red galaxies, respectively, assuming a Galactic CO-to-H2 conversion factor. By applying various conversion factor prescriptions, we also confirm a systematic decrease of SFE with galaxy's offset below the SFMS, regardless of the adopted prescription. This suggests that the low SFR in some quenched galaxies is primarily driven by suppressed SFE rather than an absence of molecular gas. Our results provide evidence that galaxies below the main sequence can retain substantial molecular gas reservoirs comparable to star-forming galaxies, but they exhibit longer depletion times and form stars inefficiently, possibly due to the combined effects of low gas density and morphological quenching mechanisms.

We present new measurements of the galaxy-galaxy lensing (GGL) signal around Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies using background sources from the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS). With high-quality imaging of background sources and a survey overlap of approximately 2650 square degrees, we obtain precise large-scale GGL measurements. Building on these new measurements, we revisit the so-called 'lensing is low' problem, wherein galaxy-halo connection models calibrated on galaxy clustering (GC) data over-predict the GGL signal by 20-40% assuming CMB-based cosmological parameters. We model the galaxy-halo connection using a halo occupation distribution (HOD), and perform joint fits to both GGL and GC signals across a wide range of scales, as well as a GC-only fit. In contrast to previous work, we do not find a significant 'lensing is low' effect in the CMASS sample, although the best joint fits are achieved by decreasing the amplitude of the matter power spectrum slightly relative to the Planck cosmological parameters. Overall, we find that two models describe our observables similarly well: one where HOD and cosmological parameters are free, and one where HOD, cosmological, and feedback parameters are free. Importantly, we emphasise the role of large scales in constraining the lensing is low effect, shifting the narrative away from an exclusively small-scale issue.

The impact of extremely low-density environments such as the diffuse intergalactic medium (IGM) on the neutral gas distribution of dwarf galaxies remains poorly explored observationally. We present deep MeerKAT HI 21 cm observations of the Local Group dwarf irregular galaxy Sextans B that achieve a spectral resolution of 1.4 km/s and reach column-density sensitivities down to 3.3 x 10^18 cm^-2, allowing us to trace the extended HI disc and faint outer structures. The low-column-density HI distribution is asymmetric and reveals a rosette-like filamentary structure superposed on the HI disc. Comparison with the stellar distribution shows offsets between the gaseous and stellar components, with the stellar disc remaining relatively symmetric while the HI envelope becomes increasingly disturbed. 3D kinematic modelling with TiRiFiC reproduces the global velocity gradient but reveals differences between the approaching and receding sides of the rotation curve at large radii, indicating departures from axisymmetric rotation. While stellar feedback can produce small-scale cavities and turbulence in dwarf galaxies, it cannot generate the filamentary HI structure, the asymmetric outer HI envelope, or the divergence between the approaching and receding rotation curves. This is consistent with interaction with a diffuse IGM. Hydrodynamical simulations tailored to Sextans B show that IGM ram pressure acting on the outer gas disc can produce asymmetric gas distributions, filamentary structures, and kinematic perturbations. The combination of morphological and kinematic signatures suggests that the outer HI disc of Sextans B is affected by ram-pressure interaction with the diffuse IGM in the outskirts of the Local Group. This is the second strong example in the Local Group, after WLM, showing that a very low-density IGM can significantly influence the gas distribution and kinematics of dwarf galaxies.

Little Red Dots (LRDs) are compact sources with broad Balmer lines, Balmer breaks, anomalous UV emission, rising red continuum, and uncertain origin. We use FIRE cosmological simulations, 3D dust radiative transfer, and synthetic emission-line data cubes to test whether ultra-compact early galaxies can reproduce LRD-like observables without invoking AGN. In progenitors of present-day group halos ($M_{\rm halo} > 10^{13.5} M_{\odot}$), we identify transient phases at $z \approx 4-8$ lasting $\sim 150-400$ Myr in which strong dissipative inflows build massive ($M_{\star} \sim 10^{8.5}-10^{10.5} M_{\odot}$), UV-bright ($-23 \lesssim M_{\rm UV} \lesssim -20$), ultra-compact ($R_{\rm eff} < 300$ pc) stellar cores with extreme circular velocity ($V_{\rm circ} > 500$ km s$^{-1}$) and consistent with several LRD properties: strong Balmer breaks ($F_{\nu}(4200{\rm Å})/F_{\nu}(3500{\rm Å}) \sim 2$); blue UV beta slopes ($\beta_{\rm UV} \approx -1.25$); dust masses; ALMA non-detections; and Balmer-line widths up to $\sim 1500$ km s$^{-1}$ broadened by galaxy-scale dynamics. However, stellar emission and host-galaxy kinematics alone do not reproduce the red rest-optical continuum, more extreme Balmer breaks ($\gtrsim 2.5$) and line widths ($\gtrsim 2000$ km s$^{-1}$), or the broad-Balmer/narrow-forbidden-line signature of broad-line AGN. The same ultra-compact conditions efficiently fuel central BHs, suggesting a hybrid stellar+AGN scenario in which compact stars explain the UV continuum, Balmer break, and intermediate line widths while AGN supply the red optical continuum and more extreme line properties. With halo masses $M_{\rm halo} \sim 10^{11-12.5} M_\odot$ and comoving abundance $\sim 2 \times 10^{-5} {\rm cMpc}^{-3}$ (for $\sim 20\%$ duty-cycle at $z \approx 4-8$), ultra-compact galaxies can contribute to the massive, bright LRD population.

We present a pedagogical introduction to the cosmological constant problem that requires only basic knowledge of quantum field theory and general relativity. A massive real scalar field is used to illustrate how the quantum vacuum energy density and pressure can be calculated both in flat spacetime and in an expanding universe. Detailed computations are provided for dimensional, cutoff, and adiabatic regularizations. No attempt is made to address quantum gravitational effects, and the expanding-universe background is treated classically. We point out that although the commonly cited discrepancy of 120 orders of magnitude between theory and observation is based on an estimate that does not account for regularization and renormalization, fundamental principles of quantum field theory nevertheless lead to a huge mismatch. In addition to this large discrepancy, we emphasize that there are also conceptual challenges related to cosmic expansion, such as the choice between comoving and physical scales in certain contexts and the non-uniqueness of vacuum.

This white paper introduces the concept, prototype design, projected costs, and scientific goals of a mobile experiment for detecting geoneutrinos originating from uranium and thorium decay chains in the Earth's mantle. This will constrain the planet's radiogenic heat production and unearth its geochemical makeup. This design of a deep-ocean mobile neutrino experiment, which is not mirrored by any active or planned experiments, supports physics and geoscience's goal of multi-modal data on the Earth's internal composition and structure. Based on geoscientific studies, this design is expected to achieve a 50--100-fold reduction in crustal background compared to similarly sized continental detectors, thereby enabling direct measurements of mantle geoneutrinos. The multiple stereoscopic projections enabled by the detector's unique mobility can map spatial variations in heat-producing elements within the mantle. Beyond discussing the design, we report on our collaboration's most recent hardware developments in the active prototyping of this detector. We briefly highlight the potential multiuse and interdisciplinary nature of this detector.

We present a minimal dark matter scenario: a single complex scalar carrying baryon and lepton number, with no new exact stabilizing symmetry. Its leading interaction is a dimension-7 semileptonic portal that, below confinement, generates a low-energy Yukawa coupling with the proton and electron. Requiring absolute stability of both the proton and dark matter forces the dark matter mass into a narrow window around the proton mass, which may be anthropically selected. Despite its minimal field content, the model can be probed by many observables: proton burning in stars, hydrogen decay, brown dwarfs and neutron star heating, and nucleon decay-like signatures in direct detection. UV-dominated freeze-in produces the observed relic abundance. This framework provides a unique testable example of dark matter arising from a minimal extension of the Standard Model.

We study warm fermionic dark matter (DM) in the framework of freeze-in at stronger coupling, in the minimal Higgs portal scenario. The reheating temperature is taken to be low, so that DM production from the Standard Model thermal bath is Boltzmann-suppressed and the DM stays out of equilibrium even for a sizeable coupling. This opens the possibility of observable signatures, in particular invisible Higgs decays. We compute the DM relic abundance including both the pre- and post-reheating contributions. We find that the fermionic DM production reaction is strongly velocity suppressed, requiring larger reheating temperatures than those obtained for scalar DM in order to reproduce the correct relic abundance. The resulting DM momentum distribution is strongly non-thermal and its shape is not captured by the common $\alpha\beta\gamma$-parametrization. We find that the Lyman-$\alpha$ constraint excludes DM masses below about $100 -180\,\mathrm{keV}$, depending on the reheating history.

The dark bubble model explains the existence of a positive cosmological constant by making explicit use of the instabilities underlying the de Sitter swampland conjectures to make the accelerated expansion of the universe inevitable. A distinctive consequence of the construction is a unique hierarchy connecting cosmological, gravitational, string, and higher-dimensional scales. In particular, the model naturally predicts the existence of a dark dimension of micron size, an idea that has been argued for on independent grounds in the literature. The same framework also predicts a weakening of gravity at distances of order the dark-dimension scale, leading to a fading of the gravitational force at micron distances. We argue that the dark bubble therefore provides a concrete realization of both the dark dimension proposal and Sundrum's fat graviton scenario, in which gravity effectively ceases to probe shorter distances. Additional predictions include a string scale of order tens of TeV and a measurable positive spatial curvature of the universe. We review these key aspects of the model, discuss their implications for gravity and cosmology, and highlight its key predictions.

We present a systematic, model-agnostic analysis of out-of-equilibrium effects, including viscosity and thermal conductivity, in non-radial oscillations of relativistic stars. Extending the Lindblom-Detweiler formalism, we construct, to our knowledge, the first general framework for linear, non-radial relativistic stellar perturbations that incorporates generic nonequilibrium corrections to the perfect-fluid sector in both the even- and odd-parity channels. Our framework is formulated in terms of the tensorial structure and thermodynamic decomposition of generic corrections without relying on any specific constitutive relations, thereby allowing us to elucidate, at a structural level, how these effects enter the perturbation equations and contribute to geometric deformations and fluid fluctuations. As an application, we consider the Bemfica-Disconzi-Noronha-Kovtun fluid and perturbatively investigate shifts in the frequencies and damping times of modes connected to their perfect-fluid counterparts in the limit of vanishing transport coefficients. We also identify structural features of the closed eigenvalue problem that can give rise to additional mode families. Our formalism provides a unified framework for analyzing how different relativistic fluid theories modify the structure of non-radial stellar perturbations.

With increasingly large numbers of gravitational-wave events, population inference is now beginning to move beyond predictions of marginal distributions and to probe correlations between compact-binary parameters such as masses, spins, and redshifts. These correlations have strong constraining power for both astrophysics and tests of general relativity. In this paper, we present an idealized analytical model to study the interplay between single-event correlations, systematic biases, and population-level correlations. With this, we investigate the potential emergence of false-positive measurements of population-level correlations. We quantify how the presence of correlations at the single-event level between a pair of parameters increases the uncertainty of population-level correlations for those parameters, potentially obscuring the true underlying population correlation if present. We also find that if waveform systematics lead to biases that are correlated across the catalog (which is likely, because certain regions of the parameter space are more difficult to model), this can be effectively absorbed by a population analysis that targets correlations and can be misinterpreted as such. This simple Gaussian-based model may serve as a broad compass for future, more detailed explorations.

The (deterministic) Landau equation captures the mean long-term evolution of dynamically hot long-range interacting finite-$N$ systems. Though successful, this kinetic equation fundamentally ignores dynamical fluctuations. Building upon Large Deviation Theory, we present a physically-consistent system of Langevin equations that simultaneously recovers the mean Landau dynamics and accurately captures the corresponding fluctuations among different realizations. We show in particular how these Langevin equations can be derived from Rostoker's principle in the limit of weak two-body deflections. We extensively validate these equations against tailored direct $N$-body simulations, showing an exquisite level of agreement.

Integrated superconducting spectrometers (ISSs) provide the instantaneous bandwidth, sensitivity, and scalable architecture for large-scale spectroscopic surveys in submillimeter-wave astronomy and cosmology. However, the accuracy with which the resonant frequencies of superconducting microstrip band pass filters can be spaced, has limited the spectral resolution for these spectrometers with continuous spectral coverage to $\frac{F}{\Delta F} < 500$. The origin of this frequency scatter has been largely unknown. In this work, we demonstrate a four-fold improvement in the frequency spacing of superconducting microstrip resonators by optimizing electron-beam lithography. We find that reducing the beam step size (BSS) on the nanometer scale reduces the random frequency scatter, and that avoiding main-field stitching across filter patterns can eliminate a systematic frequency shift between groups of resonators, indicating the different origins of these two modes of frequency deviation. These findings demonstrate that nanometer-scale control of lithographic processes is imperative for the realization of the next-generation integrated superconducting spectrometers with higher spectral resolution.

This dissertation investigates a supercooled phase transition (PT) in the early Universe. Using high-temperature dimensional reduction (DR), we compute the NLO thermal bubble nucleation rate. By explicitly evaluating fluctuation determinants, we provide a state-of-the-art description of thermal bubble nucleation. As a case study, we consider the SU(2)cSM, an extension of the conformal Standard Model with an additional SU(2)$_X$ gauge sector and scalar field that acquires a vev through radiative symmetry breaking. This symmetry breaking proceeds via a supercooled first-order phase transition. The first part of the thesis introduces the theoretical framework, including effective actions, RG improvements, finite-temperature quantum field theory, effective field theory techniques, and thermal bubble nucleation. The second part applies these methods to the SU(2)cSM. We establish a consistent power-counting scheme, construct the leading-order effective potential, analyse symmetry breaking and parameter space, derive an RG-improved potential, and incorporate thermal corrections. We then apply high-temperature DR to a classically scale-invariant model for the first time, derive the corresponding three-dimensional EFT, and compute the NLO nucleation rate. A detailed numerical evaluation of fluctuation determinants enables a comparison of different approximation schemes and their limitations. Finally, we present the phenomenological implications. We determine phase transition parameters, perform parameter scans, and predict the resulting gravitational wave signals. We find that the supercooled phase transition in the SU(2)cSM produces a strong signal detectable by LISA throughout the parameter space considered, making the model experimentally testable. We also demonstrate that higher-order corrections can significantly affect both phase transition dynamics and gravitational wave predictions.

Hadronic stars and strange quark stars could coexist within the so-called two-families scenario. In this respect, hadronic matter and strange quark matter correspond to two distinct equilibrium phases described by two different equations of state. We perform here the first detailed Bayesian analysis that makes use of astrophysical and laboratory data in order to constrain the equations of state adopted within the two-families scenario for hadronic and strange quark matter. In particular, in hadronic matter we consider the possible formation of hyperons and delta resonances (beside nucleons) within a class of non linear relativistic mean field models and in quark matter we consider the possible formation of a color-superconducting phase within a bag-like model. Results of the analysis indicate that while at the moment both the one-family and the two-families scenarios are compatible with the data, by comparing the Bayes factors of both models, the two-families scenario is favored with respect to the one-family scenario. Specifically, the two-families framework naturally relieves the tension between the intermediate-density softness of the equation of state required by small-radius objects and the high-density stiffness needed to support massive pulsars. Ultimately, future detections of even more massive compact objects, very compact ordinary-mass objects, or precise measurements of two distinct masses with the same radius, will provide strong indications in favor of the two-families scenario.

We study extreme-mass-ratio inspirals (EMRIs) evolving in a scalar cloud environment that may form through superradiant instabilities, using a fully relativistic perturbative framework that allows for eccentric and inclined orbits. EMRIs, consisting of a stellar-mass compact object inspiraling into a supermassive black hole, are key sources for space-based gravitational-wave detectors such as LISA. Previous relativistic studies of EMRIs in scalar clouds have been restricted to circular, equatorial motion. Here, instead, we focus on a Schwarzschild black hole background to incorporate eccentricity and orbital inclination. By computing the scalar energy and angular momentum scattered off to spatial infinity and absorbed at the event horizon, we show that orbital eccentricity can induce a dense spectrum of resonances near the last stable orbit, associated with strong relativistic apsidal precession. We further find that orbital inclination can significantly modify the orbital energy and angular momentum losses. In particular, we identify a critical inclination angle below which, at sufficiently small orbital radii, there is a net transfer of energy from the scalar cloud to the orbit. Moreover, for sufficiently large eccentricities, resonances associated with relativistic apsidal precession persist across the full range of inclinations, although their structure changes significantly between prograde and retrograde orbits. These results provide a foundation for future studies of EMRIs in scalar cloud environments on fully generic orbits around spinning black holes.

Modern cosmology is often taken to provide an increasingly accurate description of the universe's underlying ontology through progressively refined mathematical models. I challenge this interpretation by arguing that the empirical success of cosmology underdetermines not only ontology but also the mathematical and conceptual frameworks used to represent observational data. I propose instead that the objective content of cosmology is best identified with cross-representational informational invariants-features of observational structure that persist across empirically adequate descriptions. These invariants can be characterized in information-theoretic terms, including correlation structure, statistical distinguishability, and limits on accessible information, and formalized using tools such as the Fisher-Rao metric on model space. On this view, cosmological models are best understood as efficient encodings of observational structure rather than uniquely privileged descriptions of fundamental reality. Scientific progress, accordingly, consists not in convergence toward a fixed ontology, but in the progressive refinement of the informational structure accessible to observation.

A systematic Bayesian inference study of the equation of state (EOS) of dense matter with strangeness is presented, extending five relativistic mean-field (RMF) models with both constant and density-dependent couplings to include the full baryon octet. The hyperon-nucleon couplings in the scalar channel are varied within ranges informed by hypernuclear data, while vector isoscalar couplings are fixed by the SU(6) symmetry quark model. Observational constraints from NICER (PSR J0030, J0437, J0740) and GW170817, theoretical constraints from chiral effective field theory ($\chi$EFT) and perturbative QCD (pQCD), and experimental constraints from nuclear saturation properties are imposed simultaneously. We find that the inclusion of hyperons systematically reduces the maximum neutron star mass by $0.05$-$0.10,M_\odot$ across all models while increasing the radius at $1.4,M_\odot$ by $0.5$-$0.8$ km. The speed of sound exhibits a characteristic softening at densities $2$-$3,\rho_{\rm sat}$ coinciding with hyperon onset. All hyperonic models remain consistent with the $2,M_\odot$ constraint. Models with a more flexible isovector channel span a larger proton fraction when only nucleons are included. However, the extra flexibility is visibly suppressed by hyperons, meaning that the average proton distribution is independent of model flexibility when hyperons are included. Less flexible models show comparable or slightly increased proton fractions due to EOS stiffening when hyperons are included. Only a residual number of hyperonic equations of state give rise to a mass-radius curve with a negative slope at low masses. A $1.8,M_\odot$ neutron star with a radius larger than or similar to the radius of a $1.2,M_\odot$ star would provide strong evidence that the star contains baryonic degrees of freedom beyond nucleons.

Vacuum decay at zero temperature is generically described by a real $O(4)$-symmetric Coleman bounce. When the scalar field driving the decay carries a conserved global charge, this picture changes qualitatively: the path integral must be projected onto a definite charge sector, the Euclidean field obeys twisted boundary conditions, and the saddle is complex. For the simplest case of a $U(1)$ global symmetry, we first reformulate this problem in a two-field real Euclidean description with a real saddle. We then solve the resulting two-dimensional partial differential equation problem describing the decay of a homogeneous charged medium to a deeper vacuum via bubble nucleation. At finite charge the bounce departs from $O(4)$ symmetry, the barrier between vacua is lowered, and the decay rate increases. Continuing the solution to real time, we find that charge rearrangement around the expanding wall costs phase-gradient energy and drives the bubble to a subluminal terminal velocity even in vacuum. We also clarify how the fixed-charge construction interfaces with finite-temperature and finite-chemical-potential descriptions.

Dark matter constraint repositories are critical community infrastructure, giving experimentalists and theorists a shared landscape of existing bounds. Yet the most widely-used repositories are maintained by individual volunteers, creating a sustainability risk as the pace of new results accelerates. We present a large language model (LLM) pipeline that monitors arXiv, extracts limit curves from papers, integrates them as code, and opens pull requests (PRs) for human review. On a 346-paper benchmark whose ground truth is the upstream-curated repository itself, the pipeline classifies the coupling type correctly for 90.5% of papers and reaches a median coupling residual of 0.33 dex (a factor of two for 48% of curves), with 76% mean mass-range coverage. This is driven by treating each extraction as a noisy sample reconciled through consensus voting, a physics convention canonicalization layer built with the agentic physics assistant Get Physics Done (GPD), and a scoring methodology that separates genuine extraction error from non-comparability. The remaining difficulty is concentrated in rare coupling types with idiosyncratic conventions (macro-averaged residual 1.1 dex). The pipeline is deployed and has generated limit proposals; none have merged. Governance of AI-generated scientific data is itself an unsolved problem.

Pre-Phase-A design of lunar micro-rovers is dominated by tightly coupled mobility, power, thermal, and mass trades, yet conceptual-design tooling for the rapidly growing sub-50 kg class is typically proprietary, weakly benchmarked, or too slow to drive optimization. We contribute RoverDevKit, an open analytical evaluator coupling terramechanics, mass, power, thermal survival, and traverse that runs in 30ms per mission, fast enough to serve directly as a multi-objective optimizer's fitness function. Across mare, polar, highland, and crater-rim scenarios, NSGA-II Pareto fronts show that the binding design trade changes with mission profile within a single mass class: energy storage dominates at high latitude, slope traction on loose highland regolith, and traverse range on mare and crater-rim missions. Notably, rigid four-wheel layouts Pareto-dominate the full modeled mass range under smooth-regolith range-mass-slope objectives, contrary to the expectation that six-wheel architectures become optimal at heavier masses; six-wheel rocker-bogie layouts enter the Pareto set only once missions impose an obstacle-navigation requirement. The evaluator performance is benchmarked using both component and system checks: the terramechanics kernel matches measured single-wheel drawbar pull within the literature model-form band on two independent datasets, the bottom-up mass model predicts published in-class (5-50 kg) rover masses to 13.3% median absolute error, and a rediscovery check places real micro-rovers near the optimizer's fronts. Propagating the measured terramechanics error through the optimizer leaves the qualitative design rules unchanged. The tool, data, validation artifacts, and figure-generation scripts are released openly.

Impulsive plasma dynamics in the laboratory are often driven by rising electric currents, yet their quantitative plasma response has not been well established. By means of fully kinetic particle-in-cell simulations and laser-driven capacitor-coil experiments, we show that a rising current expels plasma, forming an expanding magnetic bubble and accelerating particles. The expansion front velocity scales with the Alfvén speed determined by the magnetic field at its inner edge and the plasma density at its outer edge. This mechanism establishes impulsive current drive as a fundamental way that generates plasma flows and accelerates particles in laboratory plasmas, with potential relevance to astrophysics.

We present a method for determining the spin parameter $a/M$ and inclination angle $i$ of a non-extremal Kerr black hole from segments of the critical curve identified in black hole images. Although the critical curve itself is not directly observable, higher-order photon rings accumulate near it, and in realistic observations localized portions of the resulting brightness enhancement may be available for identifying segments of the critical curve. We introduce standardized segments of the critical curve and define three observables that characterize their geometry. We show that these observables uniquely determine $(a/M,i)$, together with an auxiliary parameter $r_{nl}\in[0,1]$ specifying the location of the identified segment along the critical curve, within the domain considered. Thus, even a segment of the critical curve contains sufficient geometric information to constrain the black hole spin and inclination without reconstructing the full critical curve. The framework is naturally suited to realistic observations and may be extended to more general rotating black hole spacetimes.

This dissertation aims to put forth a systematic construction of a fractional-calculus extension of holographic dark energy (HDE). We show that linking late-time cosmic acceleration to non-local or memory effects encoded in a fractional (Riesz) derivative within black hole thermodynamics produces deviations from standard HDE and can address some challenges of the Hubble cutoff. In particular, a Riesz fractional spatial derivative is introduced into the Hamiltonian constraint of a Schwarzschild black hole in quantum geometrodynamics, leading to a Fractional Wheeler--DeWitt equation whose solutions yield fractionally corrected thermodynamic quantities, notably fractional Bekenstein--Hawking entropy governed by the Lévy index \(\alpha\), with \(1<\alpha\leq2\). Using this entropy with Cohen's inequality, a new dark energy density is constructed, defining the Fractional Holographic Dark Energy (FHDE) framework. The cosmological implications of FHDE are then investigated. Within the Hubble cutoff, its late-time evolution is analysed through cosmological observables, and the model is reconstructed using effective field descriptions with spin-\(0\) and spin-\(1\) candidates, allowing kinetic and potential terms to be extracted as functions of redshift \(z\) and \(\alpha\). The framework is then extended to BD, DGP, EPN, and Horndeski theories to derive the equation-of-state and deceleration parameters in terms of \(z\) and \(\alpha\). In addition, the fate of the Universe is studied through late-time singularities, namely the big, little, and pseudo-rip, within the Granda--Oliveros FHDE setting. In short, this dissertation proposes FHDE as a theoretically motivated extension of HDE, bridging non-locality in quantum gravity with the late-time dynamics of the Universe, and offering a route toward understanding cosmic acceleration beyond \(\Lambda\)CDM.

Comprehensive characterization of numerical dissipation is essential for high-fidelity simulations of magnetohydrodynamic (MHD) turbulence. In this work, we present an a posteriori framework for directly estimating numerical dissipation in MHD turbulence from simulation data without invoking a priori assumptions. Implemented in the open-source Python package PyMHD, the framework is applied to simulations of Alfvénic turbulence, turbulent small-scale dynamos, and MRI-driven turbulence, yielding a systematic characterization of the anisotropy and spectral properties of numerical dissipation across these regimes. The results indicate that numerical dissipation primarily dissipates energy transferred by the turbulent cascade at small scales, consistent with the conventional interpretation. However, its spectral properties are distinct from those of physical viscosity and resistivity, such that it cannot simply be represented by effective dissipation coefficients. In addition, numerical dissipation inherits the anisotropy of the underlying turbulence, and can even exhibit anomalous anti-dissipative behavior under certain circumstances. Moreover, this framework enables identification of the conditions under which physical dissipation dominates numerical dissipation across all scales, thereby providing practical guidance for achieving high-fidelity simulations of astrophysical MHD turbulence.

We introduce OASIS, a simulation-based inference framework for scientific settings where observations are distorted by measurement error, selection effects, and other survey-specific transformations. In many real applications, simulators generate latent, noiseless quantities, while the data are observed only after passing through a complex observational pipeline. Standard simulation-based inference methods often ignore this distinction, comparing observations to idealized simulator outputs or relying on low-dimensional summaries that can miss important structure. OASIS addresses this mismatch by explicitly embedding the observation model into the simulator and performing inference directly at the level of observed-data distributions. The method constructs a pseudo-posterior by reweighting prior samples according to a maximum mean discrepancy (MMD) loss between the empirical distributions of the observed data and forward-simulated observations, thereby avoiding both handcrafted summaries and learned neural surrogates. We provide theoretical guarantees for Monte Carlo consistency, convergence of the empirical pseudo-posterior to its population counterpart, and posterior concentration on the MMD-identified parameter set, with consistency for the true parameter under correct specification and identifiability. In controlled errors-in-variables regression experiments, OASIS delivers robust parameter recovery and well-calibrated uncertainty under heterogeneous and non-Gaussian measurement noise. We then demonstrate the method on a realistic cosmological application involving galaxy cluster observations across multiple wavelengths, in which latent physical properties are linked to observables through nonlinear scaling relations, heteroscedastic errors, selection functions, and incomplete coverage.

In our recent paper arXiv:2509.00552, we used a stringy model for quantum space-time foam to suggest that the so-induced subluminal Lorentz violation~(LV) for photons would not lead to experimentally unacceptable changes in the developments of particle showers initiated by cosmic $\gamma$-rays in the Earth's atmosphere, in contrast to other approaches to LV. The result indicated, nonetheless, at the same time that the foam can mildly modify the electromagnetic cascades under certain conditions, by suppressing pair creation on nuclei by primary photons. In this addendum, we consider how this modification affects the detection of extensive air shower~(EAS) initiated by an ultrahigh-energy cosmic-ray particle~(viz., a primary hadron), like proton with $E \sim 10^{19}~\textrm{eV}$, given that secondary photon subshowers following $\pi^{0}$ decays could be similarly influenced. We argue that fewer electrons would reach the detector and hence the energy of the primary particle may be underestimated due to foam effects, enhancing in such a way the muon content in EASs. This opens up the possibility of interpreting the alleged ``excess'' of muons, as reported by Auger and Telescope Array collaborations recently and many other experiments on high-energy cosmic rays, with a quantum-gravitational effect. Future observations are anticipated to confirm whether this anomaly really exists.

Agentic artificial intelligence (AI) systems are beginning to assist, accelerate, and partially automate scientific discovery, performing tasks that span literature synthesis, code generation, data analysis, hypothesis proposal, and model criticism. We argue that this transition is qualitative rather than incremental, and that suitably designed multi-agent systems may evolve from passive computational tools into ``AI scientists'' that can expand the hypothesis-generating and verification capacity of science. Such systems must be developed and deployed within a scientific ecosystem fit for purpose: institutions must be redesigned for verification, accountability, interpretability, and dual-use safety. We sketch how multi-agent architectures, illustrated by the prototype framework \textit{Denario}, accelerate the discovery cycle and traverse model spaces beyond human reach; examine what this implies for authorship, peer review, and the enduring role of human scientists; and close with recommendations for governing AI as an epistemic actor rather than a mere instrument.

The Diffuse Supernova Neutrino Background (DSNB), an isotropic flux arising from the cumulative neutrino emission of all stellar core-collapse events throughout cosmic history, is expected to be detected by next-generation neutrino observatories. As DSNB neutrinos propagate over cosmological distances through the cosmic neutrino background (C$\nu$B), they may undergo non-standard neutrino self-interactions ($\nu$SI), leaving distinct spectral imprints on the observed flux. In this work, we investigate the impact of scalar ($\phi$)-mediated $\nu$SI on the DSNB within a full three-flavor framework that retains the complete PMNS structure. We consider four representative flavor-diagonal coupling structures--universal, $e$-, $\mu$-, and $\tau$-specific. The resonant scattering $\nu_i\nu_k\to\phi\to\nu_j\nu_l$ off the lightest, relativistic C$\nu$B state produces broad spectral depletion whose pattern depends on the coupling structure and the neutrino mass ordering, generating distinctive signatures across the six flavor fluxes. We compute the resulting event spectra at JUNO, Hyper-Kamiokande with gadolinium loading, and DUNE, and derive projected $3\sigma$ sensitivities in the $(m_{\phi},~g)$ parameter plane. We find that these experiments can probe couplings as low as $g\sim10^{-8}$ for $m_\phi\sim100$--$300$ eV, surpassing existing bounds by up to a few orders of magnitude in the sub-100 eV mass range. Moreover, unlike the flavor-blind cosmological and supernova bounds, the DSNB sensitivity is flavor-discriminating, offering a unique opportunity to identify the underlying flavor structure of $\nu$SI in the event of a detection.

Nested Sampling is a Monte Carlo algorithm enabling posterior estimation and Bayesian model comparison, and is especially robust in multi-modal posteriors. This is because nested sampling maintains a population of live points sampled from the entire prior. In each iteration, the population is advanced above a likelihood threshold, potentially discarding modes ruled out by the data. However, the Monte Carlo nature of point replenishment can also accidentally discard a mode. We draw a connection to the neutral Moran process in genetics, and quantify the occurrence probability of this failure mode of nested sampling with a simple symmetric random walk model on the live point occupancy. We find a simple rule for setting the minimum number of live points so that mode die-out is made unlikely.

Nested sampling is a Monte Carlo algorithm for posterior estimation and Bayesian model comparison. It maintains a population of $K$ live points sampled from the prior, and at each iteration discards the lowest-likelihood point and replaces it with a new sample drawn from the prior restricted to exceed the discarded likelihood. Achieving this likelihood-restricted prior sampling efficiently and reliably is the central computational challenge. For low-to-moderate dimensional problems, MLFriends is a general and robust region-based approach that constructs a proposal region by bootstrap aggregation over the current live points and rejects proposals outside this region. We present a self-contained mathematical formulation of MLFriends and derive, under a homogeneous Binomial point process model for the live points, heuristic bounds on the expected fraction of the likelihood-restricted prior not covered by the proposal region. These bounds decay as $(\frac{1}{3}Km)^{-3/2}$, where $m$ is the number of bootstrap rounds, and are negligibly small for practical parameter choices. We show heuristically that the resulting bias in the marginal likelihood estimate is negligible compared to the inherent statistical variance of a nested sampling run. While a fully rigorous treatment remains an open problem, these results provide the first analytical characterisation of a fully specified and practically implementable nested sampling algorithm, without assuming an idealised or asymptotic sampling procedure.

Cross-correlation searches for gravitational-wave backgrounds depend on the geometrical configuration (physical separation and relative orientation) of the detectors comprising the network. Applying standard techniques to a few simple examples, we illustrate how the relative orientation of a pair of Earth-based L-shaped laser interferometers can drastically impact the detectability of both isotropic and anisotropic gravitational-wave backgrounds.

Dark matter particles that couple to the Standard Model only through gravity are usually regarded as inaccessible to laboratory detection. This expectation can change in theories with $n$ extra spatial dimensions, where gravity is enhanced at short distances and the potential scales as $1/r^{1+n}$. We reconsider the gravity-mediated dark matter (DM) interactions in Arkani-Hamed-Dimopoulos-Dvali (ADD) models with $n$ large extra dimensions. The cumulative exchange of the gravitational Kaluza-Klein (KK) modes leads to the effective strength of interactions with the Standard Model nucleons that scales as $m_pm_\chi M_*^{-4}$, where $ m_\chi$ is the mass of DM and $M_*$ is the fundamental $4+n$ dimensional mass scale. We confront this interaction with sensitivity achieved in the large Xe-based underground direct detection experiments and derive bounds on the $\{m_\chi,M_*\}$ parameter space that stretches all the way to $M_*\sim$ few TeV. We also address the indirect detection of scalar $\chi$ that can resonantly annihilate via the on-shell KK modes into the SM particles $W^\pm,Z,h$. The annihilation cross section for the process scales as $\langle\sigma v\rangle \sim m_\chi^nM_*^{-n-2}$, and stringent limits on the same parameter space can be derived from observations of high-energy galactic $\gamma$ rays.

Generating an appreciable abundance of primordial black holes (PBHs) requires a substantial enhancement of primordial curvature perturbations on small scales. In this work, we propose a new post-inflationary mechanism in which such an enhancement arises during a stiff, or kination, epoch. The mechanism is driven by metric vector perturbations sourced by the vector component of the electromagnetic stress-energy tensor associated with primordial magnetic fields (PMFs). Since these first-order vector modes remain approximately constant during kination, they act as persistent nonlinear sources for second-order scalar perturbations. We show that the resulting vector-induced curvature perturbations are amplified toward the infrared cutoff of the kination band and exhibit the characteristic scaling $\mathcal P_{\mathcal R}(k)\propto k^{-5}$. As a concrete realization, we consider PMFs generated in a Ratra-type magnetogenesis scenario and find that the induced curvature perturbations can produce PBHs with an abundance large enough to constitute a substantial fraction of the dark matter.

We construct an equation of state for isentropic dark-matter-admixed neutron stars (DMANS) with a hot core and relatively cold crust incorporating self-consistent temperature and DM density profiles for GeV-scale fermionic DM. We show that the enhancement of central stellar density due to DM accumulation, previously reported for cold neutron stars, remains robust. Substantial observable effects of DM accumulation arise only for sufficiently massive stellar configurations. Similar to earlier studies of cold NS, the speed of sound profile is shown to exhibit non-monotonic behavior for sufficiently large DM density in the core. We identify a competition between thermal effects due to nonzero values of entropy per baryon and softening effects of the dark sector which drive macroscopic properties and conformality indicators in opposite directions. This competition determines the onset of conformality near the stellar core and indicates that conformality signatures attributed to quark-matter in cold NS could be mimicked by DM admixture in isentropic stars.

High-resolution spectroscopy has provided a wealth of information about the climate and composition of ultra-hot Jupiters. However, the 3D structure of their atmospheres makes observations more challenging to interpret, necessitating 3D forward-modeling studies. In this work, we model phase-dependent thermal emission spectra of the archetype ultra-hot Jupiter WASP-76b to understand how the line strengths and Doppler shifts of Fe, CO, H$_2$O, and OH evolve throughout the orbit. We post-process outputs of the SPARC/MITgcm global circulation model with the 3D Monte-Carlo radiative transfer code gCMCRT to simulate emission spectra at 36 orbital phases. We then cross-correlate the spectra with different templates to obtain CCF and $K_{\text{p}}$$-$$V_{\text{sys}}$ maps. For each species, our models produce consistently negative $K_{\text{p}}$ offsets in pre- and post-eclipse, which are driven by planet rotation. The size of these offsets is similar to the equatorial rotation velocity of the planet. Furthermore, we demonstrate how the weak vertical temperature gradient on the nightside of ultra-hot Jupiters mutes the absorption features of CO and H$_2$O, which significantly hampers their detectability in pre- and post-transit. We also show that the $K_{\text{p}}$ and $V_{\text{sys}}$ offsets in pre- and post-transit are not always a measure for the line-of-sight velocities in the atmosphere. This is because the cross-correlation signal is a blend of dayside emission and nightside absorption features. Finally, we highlight that the observational uncertainty in the known orbital velocity of ultra-hot Jupiters can be multiple km/s, which makes it hard for certain targets to meaningfully report absolute $K_{\text{p}}$ offsets.

We present the application of a robust test of galaxy catalogue completeness to the gwcosmo pipeline. The method implements a straightforward statistical test for determining the apparent magnitude completeness limit of a magnitude-redshift sample. This offers an improved, less conservative approach compared with how galaxy catalogue completeness is currently estimated in the gwcosmo gravitational wave cosmology pipeline for determining the Hubble constant $H_{0}$. The test also does not require prior knowledge of the luminosity function, and thus returns a more robust estimate of the limiting apparent magnitude for a magnitude-redshift sample of galaxies. For GWTC-1 results using $B_{J}$-band photometry of galaxies in the GLADE catalogue, we find a $1.3\%$ improvement on the inference of $H_{0}$ using dark sirens only and a $3.4\%$ improvement for the combined posterior with GW170817. Using GLADE+, there is a $8.6\%$ improvement with dark sirens only and a $6.3\%$ improvement for the combined posterior with GW170817. However, the final posterior on $H_{0}$ using the GWTC-3 dataset with the GLADE+ $K$-band shows no improvement when applying the robust method. This is because the GLADE+ galaxy catalogue provides little or no coverage in the $K$-band for any of the GWTC-3 events. With the use of deeper galaxy catalogues in future gravitational wave cosmology analyses, the adoption of a less conservative estimate of magnitude completeness will become increasingly important.

Turbulent systems typically exhibit log-normal volume density probability density functions (PDFs) on the $s = \ln\rho$ scale, with their variance ($\sigma^2$) and skewness ($\tau$) empirically regulated by the Mach number ($M$). In this work, we explain both the $\sigma^2$--$M$ and $\tau$--$M$ relationships from a thermodynamic and cascade perspective. Entropy conservation within the compressive modes yields the fiducial relation $\sigma^2 = \ln\left(1 + M^2\right)$, while deviations from a monotonic energy cascade modify this law into a dilogarithm function. Although skewness exerts a negligible impact on the global $\sigma^2$--$M$ scaling, the characteristic skewness parameter $\tau$ obeys a similar scaling law, $\tau \propto \ln\left(1 + M^2\right)$. We demonstrate that the asymmetric wings of the global density PDF originate from underlying low-$s$ and high-$s$ skewed kernels. These kernels are governed by two distinct structural redistribution mechanisms -- the mass-fraction and volume-fraction approaches -- which exhibit a profound duality symmetry. Crucially, the high-$s$ skewed kernels are physically realizable and closely mirror the gravity-driven power-law tails of column density PDFs observed in molecular clouds.

Investigating the correlation between the TDE population and IceCube neutrinos could help us better understand whether TDEs could be potential high-energy neutrino emitters. In this paper, we perform a systematic search for TDEs that are associated with neutrinos in a sample including 143 IceCube neutrino alert events and 52 TDEs classified by the Zwicky Transient Facility (ZTF) - Bright Transient Survey (BTS). Furthermore, considering that the TDEs/TDE candidates reported as potential IceCube neutrino emitters are all accompanied by infrared (IR) echo emissions, we further select the TDEs with IR echoes from these 52 TDEs as a subsample to examine the correlation with neutrinos. Based on the Wide-field Infrared Survey Explorer (WISE) mission database, seven TDEs are identified as having IR echoes. Then we employ Monte Carlo simulations to quantify the correlation between the TDE sample/subsample and IceCube neutrinos. Finally, after considering spatial and temporal criteria, the seven TDEs with IR echoes show the most significant correlation at a 2.46$\sigma$ confidence level. If we tentatively further take the time delay factor into account, the correlation enhances to a 2.66$\sigma$ confidence level. The correlation is primarily contributed by two TDEs: AT2019dsg and AT2019azh. The latter's association with a neutrino alert, IC230217A, is newly reported in this work. We discussed the possible physical connection between AT2019azh and the neutrino event IC230217A.

Galaxy clusters in the local Universe are dominated by massive quiescent galaxies with old ages, formed at high redshifts. Whether their quenching is driven by internal processes or environmental effects is a matter of debate that has been challenging to resolve due to the lack of observations during their peak formation epoch. Here we report clear evidence from the Atacama Large Millimeter/submillimeter Array of extended and elongated gas tails in five galaxies in a forming cluster at z = 2.51. The single-tailed gas distributions, which extend notably beyond the stellar emission probed by JWST in galaxies that are relatively isolated and lack signatures of mergers or interactions (features that are very uncommon in the field), provide evidence of ram-pressure stripping. These very distant confirmed cases of ram-pressure stripping highlight the critical role of environmental effects in gas removal at high redshifts, an often-overlooked quenching pathway.

Context. A major observational challenge within the standard cosmological framework is the Hubble tension, a statistically significant ($\sim 5\sigma$) disagreement between the Hubble constant derived from cosmic microwave background measurements and the value obtained through local distance-ladder methods based on Type Ia supernovae and Cepheid variable stars. Aims. We relax the assumption of the Friedmann-Lemaître-Robertson-Walker (FLRW) distance-redshift relation and explore the influence of small-scale inhomogeneities on the propagation of light from distant sources, using the Zeldovich-Kantowski-Dyer-Roeder (ZKDR) approximation as an alternative approach to address this tension. Methods. We employ two distinct formulations of the ZKDR equation to test our hypothesis using recent Type Ia supernovae datafrom the Pantheon+ compilation and the SH0ES collaboration and six gravitational lens systems from the H0LiCOW collaboration. Results. We obtained constraints on the cosmological parameters and the ZKDR model parameters within the framework of the inhomogeneous models considered. The model comparison criterion indicates that the data show weak preference of $\Lambda$CDM over the flat ZKDR model , whereas the remaining models studied are strongly disfavored. Conclusions. Our findings indicate that a background model characterized by the ZKDR approximation and its modifications does not solve or alleviate the Hubble tension.

We discuss the equations that arise from a Higgs--Yang-Mills dark sector coupled to gravity on a flat Friedmann-Lemaitre-Robinson-Walker metric. We choose the simplest $SU(2)$ representation, which we show to be compatible with the Cosmological Principle. We devise a multiple time scale approach to solve the equations of motion through a hierarchy of the couplings, utilizing exact solutions in terms of Jacobi elliptic functions. This novel method implements the dynamical system approach used in the literature and can shed new light on the possibility that this model can describe dark energy.

We use reduced-mass eigentensors to quantify the 3D ellipsoidal shape evolution of thirteen Milky Way-mass galaxies simulated using zoom simulations with FIRE-2 physics; all but one form disks at $z=0$. We find that all of our Milky Way progenitors go through phases when they are elongated. They often oscillate between spheroidal and elongated shapes in the early Universe over billion-year timescales, with $\sim 25-45\%$ of the population having elongated luminosity-weighted shapes at any given time at $z = 0.5-8.5$. In contrast, all stellar populations in our $z=0$ Milky Way analogs are symmetric about their minor axes at $z=0$, even though the old and intermediate-age stellar populations were often arranged in the shape of elongated pickles or triaxial spheroids at the time they formed meaning these populations changed shape significantly over time. During their transient elongated phases, our galaxies have anisotropic velocity dispersion ellipsoids directed along their spatial major axis; however, their shapes {\em do not} correlate with their dark matter fraction nor with the shapes and orientations of their underlying dark matter halos. We find that when treated as a population, the fraction of our galaxy progenitors that are elongated at $z>0.5$ is roughly consistent with what is observed for systems of the same mass and redshift. Our results suggest that observed elongated galaxies seen in the early Universe with JWST and HST are not stable structures, but rather transitory phases that are nevertheless statistically common. Some of these observed objects may evolve into Milky Way-like galaxies at $z=0$.

It has been demonstrated that one can track down galaxies in absorption 'hidden' in the Lyman-$\alpha$ forest through the use of 'strong, blended Lyman-$\alpha$' (or SBLA) absorption. Specifically a series of publications studied SBLA absorption systems with Lyman-$\alpha$ flux transmission, $F_{Ly \alpha} < 0.25$ on scales of 138 km s$^{-1}$ in the Sloan Digital Sky Survey (SDSS). In order to better understand the connection between halos and these SBLAs, we make use of several million synthetic absorption spectra from the TNG50 cosmological simulation, at z=2 and z=3. We explore spectra with SDSS-like resolution in order to understand the nature of SBLAs as defined thus far, as well as with high resolution (or 'resolved') spectra to generalise and optimise SBLAs as halo finders. For the SDSS SBLAs, we find that up to 67% of these absorption systems reside in hlaos, where the stronger the absorption and the lower the redshift, the higher the probability. We also manage to recover a mean halo mass of $10^{11.78} M_{\odot}$, in line with what is measured in observations. For the resolved SBLAs, we expand on the previous definition and allow the SBLA spectra size to vary between 54 km s$^{-1}$ and 483 km s$^{-1}$. We find that the largest absorbers have the highest probability of finding halos. When applying a hierarchical framework, where we allow the largest SBLAs to consume the smaller ones, we find that the halo mass distributions for each SBLA spectral size becomes narrower with respect to the non-hierarchical case. We are also able to probe halo masses from $M_h \approx 10^{9.5} M_{\odot}$ (for 100 km s$^{-1}$ SBLAs) to $M_h \approx 10^{11.5} M_{\odot}$ (for 450 km s$^{-1}$ SBLAs). With these results, we show that we are able to transform the Lyman-$\alpha$ forest into a halo finding machine for not only identifying CGM regions, but also estimating their host halo masses.

We present deep HST imaging of one of the nearest ultra-diffuse galaxies (UDGs) outside of the Local Group: F8D1, a satellite of M81 known to be tidally disrupting. UDGs are an enigmatic and diverse population, with evolutionary pathways ranging from tidal processing to bursty feedback and high initial angular momentum. To determine F8D1's evolutionary drivers, we resolve stars in F8D1's central $\sim$1 kpc and in a parallel field $\sim$6 kpc along its major axis to deep photometric limits, reaching below the Red Clump. We also image eight shallower fields along F8D1's major and minor axes. We calculate the star formation history (SFH) in the two deep fields, finding that while currently quiescent, both regions experienced a substantial burst $\sim$2 Gyr ago and a smaller burst $\sim$500 Myr ago, which likely formed F8D1's nuclear star cluster. In the shallow fields, using the ratio of evolved Asymptotic Giant Branch and Red Giant Branch stars out to $\sim$13 kpc along F8D1's known stellar stream, we confirm that F8D1 was globally star-forming until at least $\sim$2 Gyr ago. We estimate a total progenitor stellar mass, including the stream, of $\sim$1.3$\times$10$^8 M_{\odot}$, with an average [M/H] $\sim$ $-$0.8. We compare F8D1's properties to those of Local Group galaxies with similar initial stellar mass. We find that F8D1 is consistent with a progenitor star-forming galaxy similar to NGC 6822 that is in the midst of a transition to a Sagittarius-like system. Notably, this evolutionary sequence can be accomplished through tidal processing alone in galaxies that have experienced sufficiently bursty feedback to have created cored profiles.

Massive stars lose a significant fraction of their mass through stellar winds at various stages of their lives, including on the main sequence, during the red supergiant phase, and as helium-rich stripped stars. In stellar population synthesis, uncertainty in the mass-loss rates in these evolutionary stages limits our understanding of the formation of black holes and merging compact binaries. In the last decade, the theoretical predictions, simulation, and direct observation of wind mass-loss rates in massive stars have improved significantly, typically leading to a reduction in the predicted mass-loss rates of massive stars. In this paper we explore the astrophysical implications of an updated treatment of winds in the COMPAS population synthesis code. There is a large amount of variation in predicted mass-loss rates for massive red supergiants; some of the prescriptions we implement predict that massive red supergiants are able to lose their hydrogen envelopes through winds alone (providing a possible solution to the so-called missing red supergiant problem), while others predict much lower mass-loss rates that would not strip the hydrogen envelope. We discuss the formation of the most massive stellar-mass black holes in the Galaxy, including the high-mass X-ray binary Cygnus X-1 and the newly discovered Gaia BH3. We find that formation rates of merging binary black holes are sensitive to the mass-loss rate prescriptions, while the formation rates of merging binary neutron stars and neutron-star black hole binaries are more robust to this uncertainty.

Fast radio bursts (FRBs) are among the most mysterious astronomical transients. Due to their short durations and cosmological distances, their dispersion measure (DM) - redshift ($z$) relation is useful for constraining cosmological parameters and detecting the baryons in the Universe. The increasing number of localized FRBs in recent years has provided more precise constraints on these parameters. However, the larger dataset reveals limitations in the widely used probability density function ($p_{\rm diff}$) for ${\rm DM}_{\rm diff}$, which refers to the diffuse electron term of FRB DM. In this project, we collect 117 of the latest, localized FRBs, discuss the effect of a more accurate $\sigma_{\rm diff}$, which is a parameter in $p_{\rm diff}$ and once thoughts as ``effective standard deviation'', and more clearly rewrite their likelihood to better constrain the parameters above. We find that the widely used approximation $\sigma_{\rm diff} \sim F/\sqrt{z}$ only works under contrived assumptions and shows the greatest deviation from the true standard deviation in low redshift. In general, one should use an accurate method to derive this parameter from $p_{\rm diff}$. Our method yields better constraints on $H_0\Omega_b f_{\rm diff} = 2.813_{-0.258}^{+0.250}\;{\rm km/s/Mpc}$ or $H_0 = 66.889_{-5.459}^{+6.754} \;{\rm km/s/Mpc}$ when combining the FRB data with CMB measurements and taking $f_{\rm diff} = 0.84$. This fully analytical correction helps us better constrain cosmological parameters with the increasing number of localized FRBs available today.

This study aims to model the expected luminosities of the first four Balmer-series transitions from Pop.\,III star-forming halos and assess their detectability with JWST/NIRSpec across $5 \le z \le 11$, while testing whether the massive Pop.\,III stellar systems required for detectability are physically expected to form. We use the semi-analytical code A-SLOTH with merger trees constructed from the extended Press-Schechter (EPS) formalism and cosmological $N$-body simulations targeting Milky Way-like halos and the halo population in an 8~Mpc$/h$ box. Predicted line fluxes are compared to JWST detection limits derived from the Exposure Time Calculator (ETC), assuming a 10\,000~s NIRSpec exposure at a signal-to-noise ratio of 5. For our default model parameters, Pop.\,III H$\alpha$ fluxes peak at $\sim10^{-20}$\,erg\,s$^{-1}$\,cm$^{-2}$, 1--2 orders of magnitude below the JWST detection threshold ($\sim6\times10^{-19}$\,erg\,s$^{-1}$\,cm$^{-2}$). The other Balmer lines are weaker than H$\alpha$ and are likewise undetectable. This is because, in our models, the massive Pop.\,III stellar systems required to generate detectable Balmer emission do not form. Pop.\,III star formation proceeds in short, feedback-regulated episodes that are terminated by radiative and supernova feedback, yielding young Pop.\,III stellar masses of only $\sim10^{1}$--$10^{4}\,\mathrm{M}_\odot$. In contrast, detectable Balmer emission would require Pop.\,III stellar masses of $M_{\star,\mathrm{III}}\gtrsim 10^{5}\,\mathrm{M}_\odot$, depending on the observable redshift.

We assess the viability of quasars as cosmological distance indicators based on the non-linear $L_X$--$L_{\rm UV}$ relation. We calibrate this relation in a model-independent way by anchoring quasar luminosity distances to cosmic-chronometer $H(z)$ measurements over $z\leq 1.43$, and construct a quasar Hubble diagram extending up to $z\simeq 7.5$. We compare a traditional stepwise approach, in which the calibration is fixed before cosmological inference, with a joint QSO+SN calibration--cosmology framework where calibration and cosmological parameters are sampled simultaneously. The stepwise analysis, supplemented with DESI DR2 BAO measurements and Planck compressed CMB distance priors, is used as a diagnostic benchmark, while the joint framework, with and without the SH0ES $H_0$ information, provides our main cosmological results. We selected a low-$z$ quasar subsample ($z<1.43$), matching the redshift range of the cosmic-chronometer calibration, and found calibration parameters consistent with previous studies. However, the stepwise cosmological constraints can become unstable once quasars are included, reflecting the incomplete propagation of calibration uncertainties and calibration--cosmology degeneracies. In contrast, the joint analysis yields self-consistent constraints because the quasar calibration parameters are fitted simultaneously with the cosmological parameters, allowing these uncertainties and degeneracies to be propagated into the final posteriors. Our results indicate that the current limitations of quasar cosmology are driven mainly by intrinsic scatter and possible sample-dependent effects in the $L_X$--$L_{\rm UV}$ relation, rather than by a fundamental inconsistency with standard cosmology.

The atmospheres of hot rocky exoplanets (HREs), should they persist, are products of interactions with underlying magma oceans. Spectra collected by the James Webb Space Telescope (JWST) hint at a CO/CO$_2$-rich atmosphere on the HRE 55 Cancri e, indicative of such a process. Here, we aim to identify diagnostic features that can be used to infer the composition and geochemical state of HREs. We construct a coupled atmosphere-interior model that computes the equilibrium gas speciation in the atmosphere in the system Si-Mg-Fe-O-C-H-S-N-He. The model accounts for both the equilibrium vaporisation of mineral gases and the partitioning of volatile species between the magma ocean and atmosphere. Using a fiducial planet with the properties of 55 Cancri e, we explore a parameter space that spans volatile mass fractions from 0.1 to 10 times that of the Earth, solar- to Earth-like metallicities, and 12 orders of magnitude in oxygen fugacity fO$_2$. We find fO$_2$ to be the major control of the shape of emission and transmission features. The presence of species such as SO$_2$ and the relative intensities of H$_2$O and CO$_2$ features allow to distinguish the origin of the gas, accreted or outgassed, while the atmospheric mass is more challenging to constrain. Inflated HREs, whose densities are compatible with a nebular atmosphere are rare, but a viable explanation for the planet TOI-1408 c. The majority of HREs, including 55 Cancri e, are too dense to be dominated by H$_2$-rich nebular gas yet too puffy for an Earth-like volatile budget, implying modest atmospheres of mixed heritage that are degenerate in fO$_2$, volatile mass and composition. The MIRI observation of 55 Cancri e disfavours oxidised Earth-like and reduced primoridal atmospheres alike, while the NIRCam data remain inconclusive. Future observations at wavelengths beyond 8 $\mu$m are key to discerning between potential scenarios.

We report the direct detection of gamma-ray emission from the Galactic center in the 150-600 keV band using the electron-tracking Compton camera (ETCC), which has a wide field of view of 3.1 sr. This represents the first application of this linear, imaging-spectroscopy method to observations of the Galactic center. Measurements in a one-day flight over Australia yielded significant gamma-ray detection in the light curve and revealed a $7.9\sigma$ excess over the background in the image map from the Galactic center region. These results, obtained through a simple and unambiguous analysis, demonstrate the high reliability and sensitivity of the ETCC and establish its potential for future high-precision MeV gamma-ray observations. The measured intensity and spatial distribution were tested against three emission models: a single point-like source, a multi-component structure, and a symmetric two-dimensional Gaussian. All three were found to be statistically consistent with the data. The positronium-related flux provided by the multi-component model is $(3.2~\pm~1.4) \times 10^{-2}$ photons cm$^{-2}$s$^{-1}$, consistent with the value reported by INTEGRAL within $1\sigma$. These results establish the potential of the ETCC for future high-precision MeV gamma-ray surveys.

JWST has enabled the discovery of a statistical sample of obscured (type II) active galactic nuclei (AGN) at cosmic noon. Studies comparing those type II AGN with type I AGN at that epoch have reinforced the long-standing idea of an evolutionary link between those classes of objects. Mergers, the idea goes, disturb the morphologies and angular momentum of galaxies. The disruption of angular momentum allows material to be funneled toward galactic cores, sparking AGN activity and potentially also a burst of star-formation. That material enshrouds the galactic nucleus, leading to a type II AGN. Later, AGN feedback clears the circumnuclear dust, leading to a transition into a type I AGN, and also quenches star formation. If this is a common outcome, a class of intermediate objects should exist. Such objects would be somewhat disturbed and dusty and sit below the star-forming galaxy main sequence, and their star-formation histories would show an increase in star-formation at around the time of the suspected merger. We present new JWST observations of SDSSJ2222+2745, a strongly lensed AGN at z=2.801. The lensing magnification enables a detailed study of the host galaxy spanning the rest-ultraviolet through near infrared. JWST and HST photometry, morphological models, and models of the host's spectral energy distribution reveal that SDSSJ2222+2745 is actively transitioning from a type II to type I AGN. Catching a lensed AGN at this special evolutionary phase makes SDSSJ2222+2745 a unique laboratory to study the physical processes involved in the transition and their relationships to the AGN and the host galaxy at incredible spatial-resolution down to about 20pc at z=2.801.

Recent DESI DR2 data has shown a significant preference for dynamical dark energy, yet this has further exacerbated the $H_0$ tension. In this work, we explore the potential of interacting dark energy models ($\widetilde{\Lambda}$CDM and $e\widetilde{\Lambda}$CDM) within the asymptotic-safety framework of quantum gravitational field theory to alleviate the $H_0$ tension. We perform observational constraints using the latest baryon acoustic oscillation data from DESI DR2, cosmic microwave background (CMB) data from Planck and ACT, and type Ia supernova data from DESY5 and PantheonPlus, as well as the SH0ES data. From our analysis, we observe the dynamical scale parameter of the cosmological constant, $\delta_{\Lambda} = -0.270\pm 0.100$, in the $e\widetilde{\Lambda}$CDM model using the CMB+DESI+SH0ES data, which deviates from $\Lambda$CDM at the $2.7\sigma$ level. Simultaneously, we find $H_0 = 70.84\pm 0.74~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, reducing the $H_0$ tension to $1.7\sigma$. This increase in the inferred $H_0$ is due to the anti-correlation between $\delta_{\Lambda}$ and $H_0$, whereby a negative $\delta_{\Lambda}$ leads to a higher $H_0$ value. Furthermore, for the CMB+DESI+SH0ES combination, we obtain $\Delta\chi^2_{\min}=-14.14$ and $\Delta\mathrm{DIC}=-9.18$, favoring the $e\widetilde{\Lambda}$CDM model over $\Lambda$CDM. Overall, the $e\widetilde{\Lambda}$CDM model can improve the fit and ease the $H_0$ tension, especially for the data combinations that provide the strongest statistical support.

In recent years, astrophysical observations have placed tight constraints on key properties of the nuclear equation of state (EoS). Using 93 two-dimensional simulations for three different EoS compatible with the current tight constraints, we show that the EoS remains a major uncertainty for the outcome of core-collapse supernovae. Whereas explosions are obtained in most cases for the SFHo and SFHx EoS, for the CMF EoS, which includes a crossover from nucleonic matter to a quark phase, explosions occur only for 2 out of 15 progenitors. Less favourable conditions for neutrino-driven explosions arise for the CMF EoS due to lower neutrino luminosities and mean energies and slightly weaker contraction of the warm proto-neutron star. Our results suggest that the explodability of massive stars cannot yet be predicted based on first principles without better knowledge of the nuclear EoS. Conversely, observational constraints on stellar explodability may help further constrain the EoS.

We present a comprehensive analysis of the 150~MHz radio luminosity function (LF) of star-forming galaxies (SFGs) using deep observations from the LOFAR Two-metre Sky Survey in the ELAIS-N1, Boötes, and Lockman Hole fields. Our sample comprises $\sim$56,000 SFGs over $0 < z < 5.7$. We first analyze the deepest field (ELAIS-N1), then jointly model all three fields while accounting for their distinct flux limits and selection functions. Using adaptive kernel density estimation (KDE), we reconstruct the LF continuously across redshift and luminosity without binning or parametric assumptions. The KDE results reveal clear signatures of joint luminosity and density evolution (LADE). Motivated by this, we construct and fit three parametric models--pure luminosity evolution (PLE) and two LADE variants--using a full maximum-likelihood method that includes completeness corrections and constraints from the local radio LF and Euclidean-normalized source counts (SCs). Model selection using Akaike and Bayesian Information Criteria strongly favors LADE over PLE. For ELAIS-N1, the more flexible LADE model (Model C) provides the best fit, while for the combined fields, the simpler Model B balances fit quality and complexity more effectively. Both LADE models reproduce the observed LFs and SCs across luminosity and flux density ranges, whereas PLE underperforms. We also identify a mild excess at the bright end of the LF, likely due to residual AGN contamination. This study demonstrates that combining KDE with parametric modeling offers a robust framework for quantifying the evolving radio LF of SFGs, paving the way for future work with next-generation surveys like the SKA.

Gamma-ray bursts (GRBs) are classified as long (LGRBs) and short (SGRBs), with collapsars and compact-object mergers (NS-NS or NS-Black Holes) as progenitors, respectively. LGRBs are expected to follow the cosmic star formation rate (SFR), while SGRBs follow a delayed version of the SFR. However, this division has come under question, most prominently by observational evidence of an excess of LGRBs at low redshifts by several investigations, summarized in \cite{Petrosian_2024}. Two recent observations of low-redshift LGRBs show associations with kilonovae. Both of these indicate compact mergers as a potential source of LGRBs as well. Most results showing this separation are based on analyses of small (less than 200) samples of LGRBs with measured redshifts. The aim of this paper is to use a larger sample of LGRBs. The number of LGRBs with measured redshifts has increased by more than a factor of 2 over the last decade. To this data set we add a sample of LGRBs whose redshifts are estimated using a machine learning (ML) method (\cite{Narendra_2025}). To account for the observational selection bias due to redshift measurements, we use the non-parametric, non-binning Efron-Petrosian method to establish the degree of correlation between luminosity and redshift, \textit{the luminosity evolution}, and then use the Lynden-Bell $C^-$ method to obtain the luminosity function. We find a low redshift excess for the larger sample with measured redshifts. Adding the sources with ML-estimated redshifts, which shows overabundance of the mid-range redshifts, the excess is reduced.

We present a statistical framework that establishes an accelerating star formation scenario for dense clumps using ATLASGAL and ALMAGAL samples. By employing the cumulative distribution function of dust temperature as a monotonic evolutionary indicator, we linearize clump evolution into a normalized timescale, enabling direct comparison across different samples. The virial mass of clumps increases exponentially with this normalized time, revealing an accelerating buildup of star-forming gas within protoclusters. The evolution of the maximum core mass further shows that the growth timescales of protoclusters and their embedded most massive protostars are comparable, implying a self-similar acceleration of star formation from the stellar to the protocluster scale. This unified framework naturally reproduces the observed evolution of luminosity, the core mass function, the mass growth of the most massive protostars, and the dense gas star formation law on clump scales, establishing a coherent picture of accelerating star formation across scales.

Models describing dark matter as a novel particle often predict that its annihilation or decay into Standard Model particles could produce a detectable neutrino flux in regions of high dark matter density, such as the Galactic Center. In this work, we search for these neutrinos using $\sim$9 years of IceCube-DeepCore data with an event selection optimized for energies between 15 GeV to 200 GeV. We considered several annihilation and decay channels and dark matter masses ranging from 15 GeV up to 8 TeV. No significant deviation from the background expectation from atmospheric neutrinos and muons was found. The most significant result was found for a dark matter mass of 201.6 GeV annihilating into a pair of $b\bar{b}$ quarks assuming the Navarro-Frenk-White halo profile with a post-trial significance of $1.08 \;\sigma$. We present upper limits on the thermally-averaged annihilation cross-section of the order of $10^{-24}~\mathrm{cm}^3 \mathrm{s}^{-1}$, as well as lower limits on the dark matter decay lifetime up to $10^{26}~\mathrm{s}$ for dark matter masses between 5 GeV up to 8 TeV. These results strengthen the current IceCube limits on dark matter masses above 20 GeV and provide an order of magnitude improvement at lower masses. In addition, they represent the strongest constraints from any neutrino telescope on GeV-scale dark matter and are among the world-leading limits for several dark matter scenarios.

We investigate the scale dependence of the primordial power spectrum by combining \Planck, ACT DR6, SPT-3G, and eBOSS Lyman-$\alpha$ forest data, extending sensitivity to smaller comoving scales than those probed by the CMB alone. Within a parametrisation based on a Taylor expansion around the pivot scale, we constrain the running of the spectral index $\alpha_s$ and its running $\beta_s$. By using eBOSS likelihoods exhibiting a suppression of small-scale power either in amplitude or spectral index, we show that the latter can be accommodated by correlated variations of $(\alpha_s,\beta_s)$, leading to a preference for non-zero running. We show that inflationary potentials with localised features -- such as Gaussian dips, bumps, or axion-monodromy modulations -- can reproduce the inferred scale dependence while remaining compatible with current CMB constraints. We release the public {\tt PIPE} code to enable systematic tests of inflationary potentials against current CMB datasets.

A major goal of ongoing and future cosmological surveys of the large-scale structure is to measure local type primordial non-Gaussianity in the galaxy power spectrum through the scale-dependent bias. General relativistic effects have been shown to be degenerate with this measurement, therefore requiring a non-Newtonian approach. In this work, we develop a consistent framework to compute integrated effects, including lensing convergence, time delay, and integrated Sachs--Wolfe, along with the local relativistic projection and wide-separation corrections in the multipoles of the power spectrum. We show that, for a \textit{Euclid}-like H$\alpha$-line galaxy survey and a MegaMapper-like Lyman-break galaxy survey, ignoring these effects leads to a bias on the best fit measurement of the amplitude of primordial non-Gaussianity, $f_{\rm NL}$, of around $ 3\,\sigma$ and $ 20 \, \sigma$ respectively. When we include these corrections, the uncertainty in our knowledge of the luminosity function leads to further uncertainty in our measurement of $f_{\rm NL}$. In this work, we show that this degeneracy can be partly mitigated by using a bright-faint multi-tracer analysis, where the observed galaxy sample is subdivided into two separate populations based on luminosity, which provides a $15$--$20\%$ improvement on the forecasted constraints of local type $f_{\rm NL}$. In addition, we present a novel calculation of the full multi-tracer covariance with the inclusion of wide-separation corrections~-- all of these results are implemented in the \textit{Python} code \textsc{CosmoWAP}.

Fewer gas giants have been caught in their accretion phase than mature ones are known. Extremely Large Telescope (ELT) instruments will have a higher sensitivity and a smaller inner working angle than tools up to now, which should increase search yields. We examine what METIS, the first-generation ELT spectrograph with R=1e5, can reveal about accreting gas giants. We focus on the accessible hydrogen recombination lines, mainly Brackett alpha and Pfund-series lines. Our approach is general but we take PDS70b as a fiducial case. It is similar to WISPIT2b. To calculate high-resolution line profiles, we combine a semianalytical multi-D description of the flow onto an accreting planet and its circumplanetary disc (CPD) with local non-LTE shock-emission models. We assume the limiting scenario of no extinction, appropriate for gas giants in gaps, and negligible contribution from magnetospheric accretion. We use simulated detector sensitivities to compute needed observing times. Both the planet- and the CPD-surface shocks contribute to the line, which has a Gaussian core but wider, asymmetrical wings. The line is much narrower than the free-fall velocity, and in fact has a nearly constant FWHM=30--40 km/s at low densities. For our fiducial accretion rate onto PDS70b, the Br-a line peak excess is as strong as the photospheric continuum, modulated mostly by H2O features. However, the planet's spin broadens them, helping the shock excess stand out. At Br-a, already the continuum of PDS 70 b yields a per-bin S/N=12 in 4h. The peak excess should require only 10 min to reach S/N=3. For pure shock emission, the line shape is barely sensitive to the planetary or system parameters. A complex profile would indicate that magnetospheric accretion contributes significantly. The high resolution of METIS will help remove the pseudocontinuum, evincing line shapes even of faint accretors with great fidelity.

We forward-model rest-frame $8$--$20\,\mu\mathrm{m}$ JWST/MIRI MRS spectra of 25 active galactic nuclei (AGN) with a three-dimensional radiative-transfer library in order to compare radial dust-density laws of the form $n(r)\propto r^{-p}$ over $p=0.5$--$2.0$. Within our tempered grid-based comparison, the model scores do not identify a single radial profile that is preferred for all sources. Instead, 20 of the 25 sources have their largest normalized tempered weights at $p\leq1$, while five have their highest scores at $p\geq1.5$, suggesting that both more extended and more centrally concentrated effective MIR-emitting dust distributions may be represented in the sample. The silicate feature shows a second systematic trend: absorption minima remain close to the canonical $9.7\,\mu\mathrm{m}$ wavelength, whereas emission peaks are shifted redward by about $1\,\mu\mathrm{m}$, consistent with a combination of radiative-transfer effects and dust processing in the illuminated inner regions. By contrast, the effective obscuring-geometry parameters are more tightly clustered within the adopted grid: the fitted opening-angle values cluster at $30^\circ$--$40^\circ$, and 24 sources have the intermediate radial-extent grid value $Y = 100$. These results suggest that variations in the radial dust distribution and effective dust properties are important contributors to the observed MIR spectral diversity, while the fitted opening-angle parameter is comparatively clustered within the adopted model framework.

Twenty-one-centimeter intensity mapping is a powerful probe of the large-scale distribution of neutral hydrogen (HI) and cosmological observables such as baryon acoustic oscillations. A major challenge is contamination from bright foregrounds and frequency-dependent beam effects, which can lead to signal loss in traditional methods such as principal component analysis (PCA). We develop a hybrid approach that trains a U-shaped convolutional neural network (UNet) on two input channels derived from frequency differencing (FD) and PCA cleaning, enabling it to exploit their complementary behavior across different scales. This two-channel strategy achieves improved performance, maintaining the cross-correlation power spectrum close to unity on large scales under a cosine beam and improving by 5\%-8\% relative to either FD- or PCA-based UNet alone. We further show that the method can robustly recover the HI signal even when the beam model is imperfect and differs between training and testing, with the large-scale cross-correlation remaining close to unity within the $1\sigma$ level. These results demonstrate that the proposed approach provides a robust framework for HI signal reconstruction under realistic observational conditions.

We solve time-reversed stochastic inflation in the semi-infinite flat potential with a constant drift term and derive an exact expression for the probability distribution of the curvature fluctuations. It exhibits exponential decaying tails which contrast to the Levy-like power law behaviour encountered without friction. Such a non-vanishing drift acts as a regulator for the conventional ``forward'' stochastic $\delta N$-formalism, which is otherwise ill-defined in the unbounded and flat potentials typical of plateau models of inflation. This setup therefore allows us to compare the curvature distribution derived from both approaches, reverse and forward in time. Up to similar exponential tails, we find quantitative differences. In particular, in the classical-like limit of very large drift, the tails become Gaussian but only in the time-reversed picture. As a toy model of eternal inflation, we finally discuss the case of negative drift in which inflation never ends for many field trajectories. The forward approach becomes pathological whereas the reverse formalism gives back a finite curvature distribution with always exponential tails. All these differences end up being related to the very definition of the background which is ambiguous when a classical trajectory does not exist.

Selection effects, such as interstellar extinction and varying survey depth, complicate efforts to determine the gravitational potential - and thus the distribution of baryonic and dark matter - throughout the Milky Way galaxy using stellar kinematics. We present a new variant of the "Deep Potential" method of determining the gravitational potential from a snapshot of stellar positions and velocities that does not require any modeling of spatial selection functions. Instead of modeling the full six-dimensional phase-space distribution function $f\left(\vec{x},\vec{v}\right)$ of observed kinematic tracers, we model the conditional velocity distribution $p\left(\vec{v}\mid\vec{x}\right)$, which is unaffected by a purely spatial selection function. We simultaneously learn the gravitational potential $\Phi\left(\vec{x}\right)$ and the underlying spatial density of the entire tracer population $n\left(\vec{x}\right)$ - including unobserved stars - using the collisionless Boltzmann equation under the stationarity assumption. The advantage of this method is that unlike the spatial selection function, all of the quantities we model, $p\left(\vec{v}\mid\vec{x}\right)$, $\Phi\left(\vec{x}\right)$, and $n\left(\vec{x}\right)$, typically vary smoothly in both position and velocity. We demonstrate that this "conditional" Deep Potential method is able to accurately recover the gravitational potential in a mock dataset with a complex three-dimensional dust distribution that imprints fine angular structure on the selection function. Because we do not need to model the spatial selection function, our new method can effectively scale to large, complex datasets while using relatively few parameters, and is thus well suited to Gaia data.

Stellar and AGN-driven feedback processes affect the distribution of gas on a wide range of scales, from within galaxies well into the intergalactic medium. Yet, it remains unclear how feedback, through its connection to key galaxy properties, shapes the radial gas density profile in the host halo. We tackle this question using suites of the EAGLE, IllustrisTNG, and Simba cosmological hydrodynamical simulations, which span a variety of feedback models. We develop a random forest algorithm that predicts the radial gas density profile within haloes from the total halo mass and five global properties of the central galaxy: gas and stellar mass; star formation rate; mass and accretion rate of the central black hole (BH). The algorithm reproduces the simulated gas density profiles with an average accuracy of $\sim$83-90% over the halo mass range $10^{9.5} \, \mathrm{M}_{\odot} < M_{\rm 200c} < 10^{15} \, \mathrm{M}_{\odot}$ and redshift interval $0<z<4$. For the first time, we apply Sobol statistical sensitivity analysis to full cosmological hydrodynamical simulations, quantifying how each feature affects the gas density as a function of distance from the halo centre. Across all simulations and redshifts, the total halo mass and the gas mass of the central galaxy are the most strongly tied to the halo gas distribution, while stellar and BH properties are generally less informative. The exact relative importance of the different features depends on the feedback scenario and redshift. Our framework can be readily embedded in semi-analytic models of galaxy formation to incorporate halo gas density profiles consistent with different hydrodynamical simulations. Our work also provides a proof of concept for constraining feedback models with future observations of galaxy properties and of the surrounding gas distribution.

The nature of coherent radio emission is still challenging even after more than half a century of pulsar discovery, but it is generally a consensus that single-pulse observations are essential for probing the magnetospheric dynamics, especially with the largest single-dish telescope FAST (Five-hundred-meter Aperture Spherical radio Telescope). This paper aims to explain the observed diversity of single pulse circular polarization, and to constrain the multiplicity and Lorentz factor of pulsar magnetospheric plasma, with the mode coupling model in the limiting polarization region. Assuming that circular polarization comes only from wave mode coupling, we apply a Bayesian analysis to the FAST observed single pulse circular polarization spectra, involving numerical solving of wave mode coupling equations, and analyze the posterior probability distribution functions of the parameters. Although the model fails to quantitatively fit most circular polarization spectra, circular polarization of different frequency evolution is reproduced. For three chosen pulsars, the Bayesian analysis constrains the multiplicity to be approximately $10^{0}\sim10^{2}$, and the Lorentz factor to be approximately $10^{0.5}\sim10^{2}$. Pulsar circular polarization could be induced by wave mode coupling. The plasma flow responsible for coherent radio emission carries only a very small fraction of the pulsar spin-down energy loss.

We discuss the impact of the recent this http URL-R hadronic interaction model on the scenario in which most of the cosmic rays with energies above 5 EeV originate in the nearby Centaurus A radiogalaxy. The heavier composition inferred from this hadronic model has important implications for the interpretation of the spectral features and for the anisotropies. In particular, the amount of H and He present above the ankle is now very suppressed. The elements of the CNO group from the source play a predominant role in the instep region just above the ankle, while the elements of the Si and Fe groups contribute significantly in the suppression region of the energy spectrum above 50 EeV. The lack of He from the source above the ankle also leads to a smaller expected anisotropy around the Cen A direction at energies of 10 to 20 EeV. The expected dipolar anisotropy in different energy bins above 4 EeV is well consistent with the measurements for appropriate values of the extragalactic turbulent magnetic field and source lifetime. The overall fit to the different observables improves considerably with the new hadronic model. A new method is introduced to extract the information on the cosmic ray masses from that of the depth of the maximum development of the air showers, which significantly improves the existing method.

Recent observations by the IceCube Neutrino Observatory have revealed a significant excess of high-energy neutrinos from nearby Seyfert galaxies, such as NGC~1068, without a corresponding flux of high-energy gamma-rays. This suggests that neutrinos are produced via hadronic interactions in a region opaque to gamma-rays, likely a hot corona surrounding the central supermassive black hole. However, the mechanism responsible for accelerating the parent protons to the required energies ($\sim 100$ TeV) remains an open question. In this study, we investigate diffusive shock acceleration (DSA) in active galactic nucleus (AGN) coronae using a suite of one-dimensional Particle-in-cell (PIC) simulations spanning a broad range of plasma parameters. We find that DSA is a robust and efficient mechanism for proton acceleration, consistently channeling approximately 10\% of the shock's kinetic energy into non-thermal ions, even for shocks with sonic Mach number as low as $ M_s \approx 2$. In contrast, the efficiency of electron acceleration is highly variable and less efficient ($<1\%$) in our parameter survey. These findings provide strong, first-principles support for the hadronic models of neutrino production in AGN and offer quantitative constraints that can explain the observed gamma-ray deficit.

Using VLT/MUSE data, we study the ionised-gas kinematics in a mass- and volume-limited ($M_* \geq 10^{10} M_\odot$, $D \leq 20$\,Mpc) sample of 21 nearby galaxies to identify signatures of extended shocks within their inner kiloparsec, which appear as coherent velocity jumps in kinematic maps. By removing angular momentum, shocks in gas cause inflows, which can trigger nuclear star formation and fuel AGN activity. To identify the signatures of extended shocks, we examine residual velocity fields after subtracting a modelled rotating disc, and we study velocity difference between various gas tracers. Combining our kinematic analysis with BPT ionisation diagnostic maps and dust morphology, we find that 12 of 21 galaxies ($\sim$57%) show extended shock signatures with velocity jumps consistent with models of bar-driven shocks. This is likely a lower limit, as three additional galaxies ($\sim$14%) exhibit shocks along bars, potentially reaching the nucleus but obscured by AGN outflows. We trace shock signatures inwards close to the resolution limit, which suggests that shocks may be the prevailing mechanism of inflow in the central kpc of galaxies. The only two unbarred galaxies in our sample are also the only systems with unperturbed kinematics and no shocks, strongly linking the perturbed gas dynamics in centres of galaxies to the presence of bars. All galaxies with inner bars show LINER- or Seyfert-like nuclear emission, whereas galaxies without inner bars exhibit all emission types, indicating that regardless of gas supply, inner bars suppress star formation in galactic nuclei.

Luminous fast blue optical transients (LFBOTs) are a growing class of enigmatic energetic transients. They show fast rises and declines, high temperatures throughout their evolution, and non-thermal emission in radio and X-rays. Their power source is currently unknown, but proposed models include engine-driven supernovae, interaction-powered supernovae, shock cooling emission, intermediate mass black hole tidal disruption events (IMBH TDEs), and Wolf-Rayet/black hole mergers, among others. AT2024wpp is the most optically luminous LFBOT to date and has been observed extensively at multiple wavelengths, including radio, optical, UV, and X-rays. We take models from multiple scenarios and fit them to the AT2024wpp optical, radio, and X-ray light curves to determine which of these scenarios can best describe all aspects of the data. We show that none of the multiwavelength light curve models can reasonably explain the data, and that other physical arguments disfavour models with homologously expanding ejecta. We discuss how a stellar mass/IMBH TDE of a low mass star can be tested with late-time observations, and what other scenarios could possibly explain the broadband data.

Analyses of type Ia supernovae have helped us shed light on the existence and nature of dark energy. Most of these analyses have relied on Bayesian techniques. In this work, we employ resampling techniques, namely Jackknife and Bootstrap, together with generalised least squares, to analyse supernova data. We first calibrate these techniques using near-ideal mock data and versions of the PantheonPlus data, and compare their performance with Bayesian methods. We find that with near-ideal mock data, Jackknife can yield better constraints. We then apply these methods to constrain parameters of flat $\Lambda$CDM, $\Lambda$CDM, flat $w$CDM, $w$CDM, and flat $w_0\,w_a$CDM models from the PantheonPlus and SH0ES (PPS) data. We observe that constraints obtained with different techniques for three- and four-parameter models are largely consistent. We also find that the Hubble tension is less significant with constraints from the Jackknife. For instance, we find that Jackknife estimates $h\,=\,0.743\,\pm\,0.029$ from PPS data, making the Planck value well within $3\sigma$. Moreover, we estimate $h\,=\,0.678\,\pm\,0.052$ from PantheonPlus data when we only consider sources with $z > 0.01$, in which case there is no tension with the Planck estimate. These results highlight the importance of using multiple techniques while analysing data and warrant further investigation.

We propose an infrared mechanism for alleviating the Hubble constant tension, based on a small departure from entanglement equilibrium at the cosmological apparent horizon. If the horizon entanglement entropy falls slightly below the Bekenstein-Hawking value, we parametrize the shortfall by a fractional deficit $\delta(a)$ evolving with the FLRW scale factor $a$. The associated equipartition deficit at the Gibbons-Hawking temperature then sources a smooth, homogeneous component whose density scales as $H^{2}/G$, with a dimensionless coefficient $c_{e}^{2}(a)$ of order unity times $\delta(a)$. Because this component tracks $H^{2}$, it is negligible at early times but can activate at redshifts $z\lesssim 1$, raising the late time expansion rate by a few percent without affecting recombination or the sound horizon. We present a minimal three parameter activation model for $c_{e}^{2}(a)$ and derive its impact on the background expansion, effective equation of state, and linear growth for a smooth entanglement sector. The framework predicts a small boost in $H(z)$, a mild suppression of $f\sigma_{8}(z)$, and a corresponding modification of the low-$z$ distance-redshift relation. We test these predictions against current low-redshift data sets, including SN~Ia distance moduli, baryon acoustic oscillation distance measurements, cosmic chronometer $H(z)$ data, and redshift space distortion constraints, and discuss whether the $H_0$ tension can be consistently interpreted as a late-time, horizon-scale information deficit rather than an early universe modification.

Using a combination of \textit{Hubble Space Telescope} and \textit{James Webb Space Telescope} imaging, a runaway supermassive black hole (RBH-1) was recently identified with an inferred velocity of $954^{+110}_{-126}\,\mathrm{km\,s^{-1}}$, likely ejected from a compact star-forming galaxy (denoted as GX) at $z \approx 0.96$. Assuming the runaway black hole was the outcome of the gravitational-wave-driven merger of two black holes, we use its measured runaway velocity together with gravitational-wave recoil predictions from numerical relativity and black hole perturbation theory to constrain the mass ratio and spin configuration of the progenitor SMBHs that overcame the final-parsec problem and merged $\sim 70$~Myr ago. We find that the progenitor binary must have been precessing, with a mass ratio $m_1/m_2\lesssim 6$, and that the more massive SMBH must have possessed a high spin (dimensionless spin magnitude $\sim 0.75$) in order to generate a recoil of this magnitude. This has important astrophysical implications as similar SMBH mergers can be an interesting source population for the upcoming LISA mission with signal-to-noise ratios $\gtrsim$ 1000. Furthermore, the progenitor SMBH properties imply that GX was likely formed through a major, gas-rich (``wet'') merger between two galaxies of comparable mass, with a mass ratio $\lesssim 4$.

We study through detailed simulated data and their optimized analysis the expected performance of the Single-Mirror Small-Size imaging atmospheric Cherenkov Telescopes (SST-1M) potentially located inside a high-altitude array of Water-Cherenkov Detectors (WCDs) inspired by the current foreseen design of the Southern Wide-field Gamma-ray Observatory (SWGO). For such a hybrid setup, we show an improvement in the flux sensitivity above 10 TeV by about 60% for monocular and 30% for stereoscopic SST-1M observation, due to the improved gamma/hadron separation when additional parameters from the WCD array are used. We also discuss further benefits of the hybrid gamma observatory concept and its technical challenges.

We present very deep (~11h) JWST/MIRI low-resolution spectroscopy of the rest-frame optical emission of U37126, a UV-bright (M_UV ~ -20), mildly lensed ($\mu\simeq 2.2$) galaxy at z=10.255. The continuum emission is well detected in both NIRSpec and MIRI spectra, yet no nebular recombination or metal emission lines are observed (EW(Hbeta+[OIII])<300A and EW(Halpha)<400A, at 3sigma). Combined with the exceptionally blue UV continuum slope, beta_UV ~ -2.9, and weak/flat Balmer break, these constraints indicate a stellar population dominated by very young and massive stars with a strongly suppressed nebular contribution. Comparisons with synthetic stellar population models indicate that U37126 requires both a very high ionizing photon production efficiency, log(Xi_ion / Hz erg^-1) ~ 25.75, and a nearly unit LyC escape fraction, of fesc>86% (3sigma) based on Halpha flux limit and fesc=0.94+/-0.06 derived independently from SED fitting. The best-fit SED yields a (de-lensed) stellar mass of Mstar ~ 10^7.8 Msun and a star-formation rate of SFR~10Msun/yr (sSFR~160 Gyr^-1), that along with its very compact size, reff~61pc, yields very high stellar mass and star-formation-rate surface densities, Sigma_M ~ 3x10^3 Msun/pc^2 and Sigma_SFR ~ 400 Msun/yr/kpc^2. Together with the lack of detectable nebular emission, these properties suggest that U37126 is undergoing an ``ISM-naked'' starburst phase, possibly driven by an extremely efficient gas-to-star conversion followed by strong feedback that has cleared the remaining gas from its stellar core, allowing most LyC photons to escape. Finally, we show that even a small fraction of galaxies like U37126 (~ 3%-6%), with extreme LyC production and escape, could contribute disproportionately (~ 50%-100%) to the ionizing photon budget during cosmic reionization.

We present near-infrared (NIR) spectroscopy of the hydrogen- and helium-poor (Type Ic) supernova (SN) 2024aecx, which displays a strong NIR excess emerging 32 days post peak. SN 2024aecx is a peculiar SN Ic that exhibited luminous shock-cooling emission at early times, suggestive of close-in circumstellar medium (CSM), unexpected for this class of SNe. Its early NIR spectra are typical for a SN Ic but with strong C I absorption features. By $\sim$32 days post peak, the spectra show a strong NIR excess, while maintaining normal optical colors, unprecedented for SNe Ic. We find that the NIR excess is well fit with a single-temperature, optically thin dust model with declining temperature, increasing mass, and roughly constant luminosity over time. The NIR excess appears too promptly for dust to have formed in the SN ejecta, indicating an IR echo from pre-existing dust in the CSM. The IR echo is likely powered by the relatively slowly evolving SN peak light, and not the brief shock cooling emission, as the latter requires unrealistically high CSM densities to explain the observed dust mass. We consider different potential CSM geometries and find that a thick face-on disk with an inner edge of around $5\times 10^{16} \rm \ cm$ can best explain the dust mass and temperature evolution. In this scenario, the SN shock should start interacting with this CSM $440\pm200$ days post explosion. CSM around SN Ic is rare, and follow-up observations of SN 2024aecx will probe the mass-loss process responsible for removing hydrogen and helium from their progenitor star.

In this work, we present an updated prescription of contemporary tidal dissipation theory adapted for rapid binary population synthesis. Our simplified expressions encode the dependence of tidal dissipation on stellar structure, stratification, and tidal forcing frequency, while remaining computationally efficient. We implement these prescriptions in the rapid population synthesis code COMPAS, and demonstrate the self-consistent coupling of tides with stellar evolution and binary properties such as orbital periods, spins, and eccentricities for several representative binary systems. When compared with commonly used tidal prescriptions, our equilibrium tidal dissipation efficiencies can be stronger by 1-2 orders of magnitude for low mass main sequence and giant type stars, and dynamical tides can be stronger by 1-7 orders of magnitude due to the explicit dependence on internal stellar structure and the presence of inertial wave dissipation. Despite our simplistic approach, our models agree with detailed stellar simulations to within an order of magnitude across tidal dissipation mechanisms.

Radio relics in merging galaxy clusters are widely interpreted as synchrotron emission from relativistic electrons accelerated at large-scale shocks. However, the efficiency of diffusive shock acceleration (DSA) is expected to be suppressed in the low-Mach-number, weakly turbulent environments of cluster mergers; furthermore, recent theoretical insights suggest that DSA may not constitute a viable physical mechanism for such environments. In this work, we investigate ballistic surfing acceleration (BSA) as an electrodynamically grounded alternative for electron energization that bypasses the need for prescribed diffusion coefficients. We formulate BSA under typical cluster shock conditions, deriving the balance between coherent acceleration by the convective electric field and radiative losses from synchrotron and inverse-Compton cooling. This equilibrium defines the maximum reachable electron energy and constrains the resulting steady-state spectrum. By forward-modeling the associated synchrotron emission and comparing it with integrated radio observations of the `Sausage' (CIZA J2242.8+5301) and `Toothbrush' (1RXS J0603.3+4214) relics, we find that the observed spectral curvature and high-frequency steepening are consistent with BSA-limited energies, provided that active acceleration involves only a minute participation fraction ($10^{-9}$-$10^{-8}$) of the radiating electrons. Despite this high selectivity, BSA effectively produces Lorentz factors of $\gamma \sim 10^4$-$10^5$. Our results suggest that radio relics serve as prime astrophysical laboratories for probing coherent acceleration, with the BSA framework providing a robust and physically consistent explanation for electron energization in cluster shocks.

Forbush decreases (FDs) are transient depressions in the galactic cosmic-ray flux observed by global neutron-monitor networks and are commonly associated with interplanetary disturbances driven by coronal mass ejections and related shocks. Despite extensive observational work, quantitatively comparing FD morphology across events and linking it to storm severity remains challenging due to heterogeneous station responses, coverage gaps, and the multivariate nature of the network. This work introduces a graph-based event representation in which each FD is mapped to an event network constructed from pairwise dissimilarities between station response time series. A controlled sparse backbone is obtained via the minimum spanning tree, enabling comparable event graphs across cases. From each graph, a compact set of geometric/topological fingerprints is computed, including global integration measures, spectral summaries, mesoscopic structure, centrality aggregates, and complexity descriptors. Predictive skill is assessed using strict leave-one-event-out validation over a pre-defined grid of distance metrics and distance-domain transformations, with selection criteria fixed \emph{a priori}. The proposed fingerprints exhibit measurable signal for three tasks: (i) multi-class classification of geomagnetic storm intensity (G3/G4/G5) with moderate but consistent performance and errors dominated by adjacent categories; (ii) stronger binary severity screening ($\ge$G4 vs. G3) with high sensitivity to severe events; and (iii) drop regression with partial least squares achieving positive explained variance relative to a fold-wise mean baseline.

Little red dots (LRDs) draw extensive attention because of their unique observational characteristics and apparent overabundance in the early Universe, raising new insights into early black hole formation and growth. Early studies show that LRDs exhibit weak variability in broad-band photometry and emission-line fluxes, suggesting a preference for super-Eddington accretion or disfavouring an AGN origin. However, the cadence of the current data, and therefore, the resulting light curves for LRDs, is limited, preventing us from placing strong constraints on their variability. Based on Zwicky Transient Facility (ZTF) light curves with a baseline of $\sim6$ years, we here study the optical variability of seven previously reported local analogs of LRDs at $z \sim 0.3$, offering an insight into LRDs from a low-redshift sample. Three out of seven local analogs show excess variances on all three bands of their light curves, and two of them can be fitted with the damping random walk model, supporting their AGN origins for the variability. The remaining sources show weak variance in at least one band, but no detectable variability at the current sensitivity level, exhibiting $\rm SF_\infty$ upper limits consistent with estimates from high-redshift (high-$z$) LRDs. Their non-detection of variability is likely due to the large photometric uncertainty. As an implication, by simulating long baseline light curves with the variability amplitude of local analogs and adopting JWST observation cadence, we investigate the limitation of the variability amplitude estimate for LRDs. Our mock observations imply that the current constraints on LRDs' variability are probably underestimated. This underestimation might be induced by the short temporal baseline of observations, as well as the intrinsic scatter of the empirical $M_{\rm BH}-\tau$ relation.

Using N-body simulations, we examine the impact of dark matter (DM) halo resolution and gravitational softening on bar formation. We generate isolated disk-halo systems with fixed stellar disk parameters, varying the number of halo particles, softening lengths, and halo concentration to modulate disk stability via the central DM fraction. The effects of DM resolution ($\mratio=1$, 10, and 100) on bar formation are less pronounced in more unstable disks, in which the overall evolutionary path is similar except that the lowest DM resolution model suffers gradual bar weakening. Irrespective of the halo resolution, large softening, $\epsdm$, flattens the central halo density profile within the softening scale, impeding angular momentum transfer to the nascent bar and preventing bar formation in more stable models. In unstable models with $\epsdm=0.96 \, \kpc$, a small bar still emerges due to enhanced initial instability and a larger seed perturbation, yet its strength remains capped at $F_2 \approx 0.3$ owing to unresolved central dynamical friction. Despite the destabilizing effect of reduced central DM fractions, our results indicate that deficient central angular momentum exchange can still suppress bar growth. Furthermore, halo softening influences buckling instability, as larger values ($\epsdm=0.30$ and $0.60 \, \kpc$) inhibit central vertical heating, exacerbating radial-vertical velocity dispersion anisotropies and triggering stronger buckling. We recommend adopting $ \mratio \le 10 $, $ \mstar \leq 10^4 \, \Msun $, and $ \epsdm < 0.30\,\mathrm{kpc}$ when investigating the formation and evolution of non-axisymmetric structures in Milky Way-mass galaxies.

We present the first constraints on multipole-dependent cosmic birefringence using CMB polarization data from the BK18 dataset, which combines observations from BICEP2, Keck Array, and BICEP3 at frequencies of 95, 150, and 220 GHz. Photon coupling to an axion-like field leads to the rotation of CMB polarization, inducing non-zero EB cross-correlations. We show that a multipole-dependent rotation beta(l) imprints a distinct signature in the polarization spectra that can be constrained. Specifically, we consider an Early Dark Energy (EDE) scenario in which a pseudoscalar field couples to photons through a Chern-Simons interaction, generating a polarization rotation with multipole dependence. We introduce a phenomenological beta(l) as a step function, obtaining constraints on the step function size consistent with zero, with uncertainties less than 0.15 degrees (68% CL). In addition, using multi-frequency EE, BB, and EB cross-spectra, along with robust BICEP/Keck foreground treatment and likelihood framework, we derive constraints on the axion-photon coupling amplitude g for several choices of EDE parameters. For the baseline best-fit value f_{EDE} = 0.087 from the Planck 2018 analysis, we obtain g = 0.11 +/- 0.37 (68% CL), consistent with previous limits.

The observed GWB spectrum is higher in amplitude than model predictions by a factor of 2-3. Using a semi-analytic model, we evaluate the effect of a high-scatter supermassive black hole (SMBH) scaling relation ($M_\mathrm{BH}$-$M_\mathrm{bulge}$) on models of the nanohertz gravitational wave background (GWB). By implementing an intrinsic scatter of the $M_\mathrm{BH}$-$M_\mathrm{bulge}$ relation, which is larger at higher redshift, but matches local observations, we find that the amplitude of GWB models increases to be consistent with the low-frequency end of the GWB spectrum. This amplitude increase is not uniform across frequencies, a strongly evolving scatter preferentially increases the number density of the most massive SMBHs which, in the GWB spectrum, minimizes the strength of the low-frequency turnover. Our models with positively evolving intrinsic scatter can reproduce the electromagnetically observed overmassive SMBHs at $4 < z < 6$ without changing the $M_\mathrm{BH}$-$M_\mathrm{bulge}$ normalization though we find that including moderate normalization evolution marginally improves fits to the GWB data. We conclude that the $M_\mathrm{BH}$-$M_\mathrm{bulge}$ relation which best describes the available GWB and electromagnetic data sets has intrinsic scatter that evolves as $\varepsilon(z) = \varepsilon_0 + (0.56 \pm 0.4) \log_{10}(1 + z)$ and normalization that evolves as $\alpha(z) = \alpha_0 (1 + z)^{0.84 \pm 0.35}$. The results of this work imply that the $M_\mathrm{BH}$-$M_\mathrm{bulge}$ relation we see today is not universal throughout cosmic time and that a diversity of seeding models and growth mechanisms may be at play in the early stages of SMBH-galaxy evolution.

The optimization and interpretation of microlensing surveys depends on having an accurate model of the Milky Way. However, existing population synthesis Galactic modeling tools often perform poorly in replicating the stellar contents of the inner Galactic bulge region and reproducing microlensing survey results. We present an updated Galactic model implementation within the \synthpop framework that has been tuned for simulating the upcoming {\it Nancy Grace Roman Space Telescope}'s Galactic Bulge Time Domain Survey (RGBTDS). We evaluate the model against stellar catalogs and kinematics from optical and infrared surveys toward the Galactic bulge, finding good agreement in much of the bulge, including the RGBTDS' contiguous lower bulge fields. However, within Galactic latitudes of $b\lesssim0.5^\circ$ of the Galactic plane, some inconsistencies arise which may impact projections for the RGBTDS' Galactic center field. The model over-predicts optical microlensing event rate per star measurements by a $\sim20$\%, but detailed comparisons to near-infrared measurements are hampered by their lack of detection efficiencies. {\it Roman}'s GBTDS and Galactic Plane Survey will be instrumental in resolving the remaining model inconsistencies and improving our understanding of the structure of the central few degrees of our Galaxy.

Photometric classification of Type Ia supernovae is essential for modern time-domain surveys, where spectroscopic confirmation is not always feasible for the full transient sample. We investigate a compact and physically interpretable feature representation derived from multi-band light curves and evaluate its performance using gradient-boosted decision trees on the Supernova Photometric Classification Challenge (SPCC) dataset. The compact representation is derived from an initial pool of 31 light-curve features, reduced to 30 after removing redundant variables and further optimized to a 16-feature model through systematic ablation analysis. The final compact model achieves an F1-score of 0.844 on the held-out test set, consistent with k-fold cross-validation results (0.841 +/- 0.006). The precision-recall area under the curve (PR-AUC) is 0.928, with similarly low variance across folds. Ablation experiments show that temporal evolution provides the dominant classification signal, while brightness, color, and variability features contribute complementary information. A reduced core of approximately ten physically meaningful features retains most of the performance of the compact model, with only a small decrease in F1-score, indicating that reliable classification does not require large high-dimensional feature spaces. These results demonstrate that interpretable feature-based models can capture the essential astrophysical information needed for Type Ia photometric classification, with implications for survey cadence, filter coverage, and the design of transparent and efficient machine-learning pipelines for time-domain surveys.

As the third paper in a series regarding the estimation of luminosity functions (LFs) via kernel density estimation (KDE), we present a further generalization of our framework by extending its applicability to multiple flux-limited samples. While our previous works addressed single flux-limited datasets, many practical applications involve surveys that cover disjoint fields of view with different flux limits. We introduce a piecewise estimation framework that partitions the luminosity-redshift plane into disjoint regions according to the staggered flux limits of the sub-samples. Within each region, we integrate data from all surveys capable of detecting sources into a combined sample and apply the transformation-reflection KDE method using the corresponding local flux threshold as the truncation boundary. This strategy allows for the full utilization of all available sources while maintaining rigorous statistical consistency. The robustness of this approach is validated through Monte Carlo simulations. Furthermore, application to SDSS DR7 and 2SLAQ quasar data shows overall agreement with parametric models, while a small residual discontinuity near a survey-transition boundary is discussed as a diagnostic of independent piecewise estimation and possible inter-survey systematics. The KDE calculations in each piecewise region are performed using our previously developed public Python package \texttt{kdeLF}.

Magnetars are highly magnetised, isolated neutron stars with uncertain formation channels. They comprise a potentially significant fraction of the young neutron star population in the Milky Way, and are implicated in the explosion mechanisms of some of the most powerful explosions in nature. We aim to identify magnetars in the near-infrared with Hubble Space Telescope (HST) and James Webb Space Telescope (JWST) imaging, in order to measure their proper motions and search for their birth sites. Candidate infrared counterparts are selected based on variability, colours and proper motions which are outliers with respect to sources in the field. Proper motions are obtained by tying HST and JWST images to the Gaia absolute astrometric reference frame. We newly identify infrared counterparts for PSRJ1622-4950, 1RXSJ170849.0-400910 and CXOUJ164710.2-455216, representing a substantial increase in the population. The past trajectory of the 1RXSJ170849.0-400910-associated source coincides with the supernova remnant G346.6-0.2. The transverse velocity distribution is found to be marginally inconsistent with young pulsars, due primarily to a dearth of high velocity magnetars. A candidate birth site is identified in nearly every case. We show, based on the inferred kinematic ages, that magnetar characteristic ages may frequently be lower than the true age, but caution that this depends on the reliability of the birth site associations. We conclude that magnetars are broadly similar in terms of their kinematics and birth sites to the wider Galactic neutron star population, consistent with magnetar formation being a common outcome of core-collapse. However, tentative evidence for a dearth of high-velocity magnetars is emerging. If real, this may arise from physical differences in the progenitor population giving rise to magnetars, or from differences in their post-formation velocity evolution.

We investigate the kinematic properties of the Coma galaxy cluster using a new, large spectroscopic sample of member galaxies, from the Dark Energy Spectroscopic Instrument (DESI). By means of the MG-MAMPOSSt code, based on the Jeans equation, we jointly reconstruct the total cluster mass profile and the velocity anisotropy profile. Assuming a Navarro-Frenk-White model, we estimate a virial mass $M_{200}=1.04_{-0.08}^{+0.07}~({\rm stat})\pm 0.09~({\rm syst})\times 10^{15}\,\mathrm{M}_\odot $, corresponding to $r_{200}=2.07 \pm 0.05\,\mathrm{Mpc}$ and a scale radius for the mass profile $r_{\rm s}=0.73^{+0.24}_{-0.30}\,\mathrm{Mpc}$, which provides the tightest robust kinematic mass profile constraint to date. By considering separately the mass of the hot gas and the galaxy stellar mass, we determine the dark matter mass profile, with $M_{200}^{\rm DM}=8.6^{+1.2}_{-0.8}\times 10^{14}\,\text{M}_\odot$. We discuss the impact of the mass and number density parametrisations, the effect of different choices of the cluster's rest frame and of the radial range of the kinematic analysis, further comparing our results with previous estimates from the literature. The cluster dynamical state has also been assessed, using the spatial and line-of-sight velocity distributions of the members. We perform a kinematic study of different subsamples of galaxy populations, based on their colour (red sequence, green valley, and blue cloud), focusing on the anisotropy profiles and line-of-sight velocity distributions. The orbits of green valley and blue cloud galaxies appear to be more radial in the centre and in the outskirts, respectively, with the latter predicting a higher cluster virial mass. This study provides new insights on the interplay between dynamical and intrinsic properties of galaxies in massive structures, fundamental to verify the tight connection between galaxy evolution and environment.

Fast astronomical transients were observed by the VASCO Project (Villarroel et al 2020) in photographic sky surveys conducted in the 1950s. Those searches analyzed the Palomar Observatory Sky Survey (POSS-I and POSS-II) digitized plates. In this article, we present a preliminary report on a similar but independent search using archival plates taken at the Hamburg Observatory with the Großer Schmidtspiegel 1.2-m Schmidt camera, also from the mid-1950s. These plates were digitized by the APPLAUSE Archive, which provides both images and tables of detected objects. By analyzing pairs of plates taken in rapid sequence (about 30 minutes apart) of the same sky regions, we find evidence of transients similar to those previously reported by the VASCO Project for POSS plates. While the analysis is ongoing, one notable result is that our findings independently confirm that these transients exhibit systematically narrow full width at half maximum (FWHM) compared to stellar point spread functions. This provides further support for their interpretation as sub-second optical flashes, consistent with reflections from flat, rotating objects in orbit around Earth.

We present chemical abundance ratios of 8 nitrogen-rich ([N/O]$>0.3$) galaxies at $z\sim 6-12$ identified by the first 4 years of the JWST observations, and compare these ratios with chemical evolution models. We reanalyze the JWST/NIRSpec data of these galaxies in the self-consistent manner for line fluxes and upper limits including those previously unconstrained. We derive the abundance ratios and constraints of [N/O], [C/O], [Ne/O], [Ne/C], [Ar/O], [S/O] and [Fe/O], characterizing the nebulae in the galaxies with the electron temperatures and densities measured with {\sc[Oiii]}$\lambda4363$ and {\sc[Oii]}$\lambda\lambda3727, 3729$ lines, respectively. We develop the chemical evolution models for the three major scenarios, Wolf-Rayet stars, supermassive stars, and tidal disruption events (TDEs) with the AGB star contribution, integrating the ejecta of the stars and core-collapse supernovae (CCSNe) over the age with yields calculated by numerical simulations. We compare the models with the [N/O] measurements and stellar ages, and find that all of the scenarios reproduce [N/O] as high as those of our galaxies. However, the time-scales of the high [N/O] ratios are too short to explain our galaxies in any of the scenarios, suggestive of very frequent failed supernovae that do not increase oxygen against nitrogen. We find that the three scenarios are distinguished in the plane of [Ne/C] vs. [N/O] due to Ne production outside CNO cycle, and that the observed abundance ratios are explained by the Wolf-Rayet models better than supermassive-star and TDE models. We argue that abundance ratios of various elements and time scales are clues for understanding nitrogen-rich galaxies.

We investigate the constraining power of future post-reionization and galaxy surveys on possible interactions between dynamical dark energy and dark matter. The analysis focuses on the interaction strength and the dark energy equation of state parameters, in addition to the six standard cosmological parameters. Using fiducial values obtained from the current observational bounds (Planck 2018 + DESI DR2 + Pantheon+), mock datasets for upcoming 21-cm intensity mapping, galaxy clustering and cosmic shear observations from the SKA-mid, and for the upcoming large-scale survey from the Euclid mission, were generated. Subsequently, Markov chain Monte Carlo analyses combining current cosmological data with these mock datasets were performed to forecast parameter constraints. The results indicate that both SKA-mid and Euclid observations can significantly improve constraints on interacting dark sector parameters. In particular, the interaction strength and dark energy equation of state parameters can be constrained considerably tighter than current combined constraints from Planck 2018, DESI DR2 and Pantheon+. Comparing different probe combinations and survey configurations, it is found that SKA2 provides the tightest projected constraints, particularly on the interaction strength, while Euclid achieves a precision broadly comparable to that of SKA1. The results highlight the potential of these upcoming surveys to probe interactions within the dark sector.

We develop a transport-geometric theory of cosmological peak statistics based on optimal transport and entropy geometry. The density field is treated as a probability measure in Wasserstein space, and its local structure is characterized by a logarithmic curvature tensor obtained as the localized response of an entropy functional. Peaks are thereby defined as positive-curvature stationary points, and their abundance is formulated as a curvatureconditioned measure on local tensor space. In the Gaussian-linear limit, this measure admits a finite-dimensional closure in terms of the spectral moments of the density field. The resulting peak abundance reduces exactly to the classical BBKS formula, identifying BBKS as a solvable Gaussian closure of a more general geometric structure. This formulation separates peak statistics into three fundamental ingredients: the probability distribution of local variables, the positive-curvature constraint, and the induced geometric measure. The theory extends naturally beyond the Gaussian approximation. Nonlinear evolution appears as a deformation of the logarithmic curvature geometry, while primordial non-Gaussianity is interpreted as a deformation of the curvature-conditioned measure itself. We further formulate two- and three-point peak statistics as higher-order curvature-conditioned measures and show that the resulting hierarchy can be organized as response functions to long-wavelength background modes, with conventional peak bias emerging as the lowest-order response coefficient. These results provide a unified description linking optimal transport, curvature geometry, peak statistics, and cosmological observables, and establish a systematic framework for studying nonlinearity, scale dependence, primordial non-Gaussianity, and higher-order peak correlations.

Supercritical gas filaments in molecular clouds host the dense cores in which new stars form. The mechanisms governing their formation and subsequent gas accretion remain poorly understood. In this study, we conduct a statistical analysis of a large sample of sub-parsec supercritical filaments using H13COp J=1-0 data from the ALMA Three-millimeter Observations of Massive Star-forming regions (ATOMS) Survey. We identified velocity-coherent filaments in position-position-velocity (PPV) space and systematically examined velocity gradients both along and perpendicular to their skeletons. Our analysis uncovers a remarkable result: at scales of ~ 0.1-1 pc, the local velocity gradients within these supercritical filaments show no preferred alignment with the filament skeletons and exhibit no correlation with the local gravitational field. This random orientation suggests the presence of chaotic gas motions deep inside these dense structures. These findings may indicate that turbulence-rather than gravity-dominates gas dynamics and structural evolution at small scales, even in regions on the verge of star formation, challenging the paradigm of gravity-dominated structure formation within molecular clouds. This scenario should be further tested by more state-of-the-art simulations. This study offers key observational insights into the roles of turbulence and gravity in establishing the initial conditions for star formation.

We infer recoil (kick) velocities for both individual binary black hole (BBH) mergers and candidate intermediate-mass black hole events, as well as for the BBH populations inferred from GWTC catalogs up to GWTC-5. We obtain informative recoil constraints for several events, including GW231028-153006 ($v_{\rm kick}=839^{+1018}_{-681}\,\mathrm{km\,s^{-1}}$) and GW231123-135430 ($v_{\rm kick}=974^{+944}_{-760}\,\mathrm{km\,s^{-1}}$), while finding that the majority of event-level recoil posteriors remain broad and only weakly informative. We further infer consistent population-level recoil distributions across GWTC-3, GWTC-4, and GWTC-5, with median kick velocities of approximately $300$--$330\,\mathrm{km\,s^{-1}}$. Using both event-level and population-level recoil estimates, we find typical retention probabilities of $\sim2$--$3\%$ for globular clusters, $\sim28$--$32\%$ for nuclear star clusters, $\sim25$--$29\%$ for dwarf galaxies, and $\sim92$--$94\%$ for elliptical galaxies. We also compute recoil-induced displacements and dynamical-friction return times, finding that retained remnants in globular clusters and nuclear star clusters can remain displaced from their host cores for extended periods. Our results show that retention alone is not sufficient to determine the prospects for hierarchical mergers: hierarchical-merger efficiency depends on both remnant retention and post-kick re-centering.

Magnetars are usually interpreted as highly magnetized neutron stars, yet a small subset of low spin-down sources has motivated alternative scenarios involving highly magnetized white dwarfs. We test whether the observed magnetar sample is consistent with a single neutron-star population or whether the data favor an additional compact-object channel. We combine exploratory machine-learning diagnostics with hierarchical Bayesian population modeling. First, we apply K-means clustering and principal component analysis in a five-dimensional feature space $(P,\dot{P},L_X,kT,|Z|)$, where $P$ is the spin period, $\dot{P}$ its time derivative, $L_X$ the X-ray luminosity, $kT$ the thermal spectral temperature, and $|Z|$ the absolute Galactic scale height. We then train a Random Forest classifier with leave-one-out cross-validation to identify the observables driving the empirical split. Subsequently, we construct a hierarchical Bayesian mixture model linking spin parameters to magnetic-field distributions through covariate-dependent mixing fractions. Posterior inference is performed with Hamiltonian Monte Carlo, and predictive performance is assessed using Pareto-smoothed importance sampling leave-one-out cross-validation. The exploratory analysis reveals a reproducible substructure: the Random Forest achieves $>95\%$ LOOCV accuracy, with $L_X$, $\dot{P}$, and $kT$ emerging as the dominant predictors. However, Bayesian model comparison shows no statistically significant preference for a two-population model. Instead, a few low spin-down sources receive intermediate posterior membership probabilities, suggesting transitional or outlying behavior rather than membership in a distinct class. Overall, current data do not require a separate white-dwarf magnetar population and are adequately described by a predominantly neutron-star population.

We combine Gaia DR3 5-parameter astrometry with calibrated radial velocities for 23 nearby (<1 kpc) young (<60 Myr) clusters, with membership lists from Cantat-Gaudin et al. (2020). We characterise the plane-of-sky structure of the clusters using Q-Parameter and Angular Dispersion Parameter (ADP) methods. We measure plane-of-sky expansion using several methods. We determine plane-of-sky orientations along which expansion is maximised. We also estimate expansion timescales and traceback ages and compare to isochronal ages. We then look for correlations between cluster properties and discuss sample-wide trends. We find that most young clusters are more smoothly structured in their centers where the rate of dynamical interactions is highest, while hierarchical structure can survive in the sparse outskirts for >10 Myr. We also find that the majority of nearby young clusters exhibit clear signatures of expansion in the plane-of-sky, which in many cases is significantly anisotropic, even at ages >30 Myr. We find evidence that older clusters tend to have directions of maximum expansion oriented closer to parallel with the Galactic plane. The high degree of spatial structure and significant expansion anisotropy imply that the majority of these young clusters have formed with significant spatial and kinematic substructure and not as dense, monolithic clusters. Kinematic ages estimated from expansion timescales and on-sky traceback are generally in good agreement with estimates inferred from stellar evolution models for clusters <10 Myr old. However, many clusters with older isochronal ages appear to have significantly younger kinematic ages. We discuss potential reasons for this discrepancy, including a prolonged embedded and/or gravitationally bound phase in the early stages of the clusters.

The Earth slowly decelerates in its rotation due to the energy dissipation caused by the interaction with the Moon. This leads to the continuous increasing in the length of the mean solar day (aka, length-of-day, or, LOD) relatively to 86,400 solar seconds at an average secular rate of +1.8 ms per century. But, on a shorter time scale the process is uneven. A positive leap second is used to be introduced on regular basis to support a consistency between the astronomical and atomic timescales. However, nowadays the LOD is steadily sparking a discussion about the timescale maintenance, in particular, from fears that a negative leap second will have to be introduced for the first time in the foreseeable future. The aim is to show that the LOD is currently dominated by the 18.6 yr lunar nutation signal whereas the long-term trends are essential for extrapolation after 2030. The LOD data since 1962 are used to estimate the long-term variations along the 18.6 yr and other harmonic signals in its spectrum. It is shown that the influence of the lunar nutation impact on the LOD variations was underestimated. At the moment, the LOD changes are completely determined by a signal with a period of 18.6 yrs. More detailed extrapolation reveals that LOD is likely to vary in a range between -1 ms to +1 ms until 2050 or may be longer.

The Galactic diffuse gamma-ray emission is conventionally modeled as the product of cosmic-ray interactions with the interstellar medium. However, the cumulative contribution of stellar atmospheres acting as hadronic interaction targets remains an unexplored multi-messenger background. In this work, we present the first systematic evaluation of this stellar diffuse emission by coupling MESA stellar evolution profiles and magnetic-field-modulated cosmic-ray transport with a 3D Galactic population synthesis framework. We find that the cumulative stellar contribution to the Galactic diffuse gamma-ray flux is negligible at 1 TeV, and the associated diffuse neutrino flux ($\sim 10^{-16}\;\mathrm{TeV\;cm^{-2}\;s^{-1}\;sr^{-1}}$) remains orders of magnitude below current IceCube limits. Nevertheless, at ultra-high energies ($>10\;\mathrm{TeV}$), this emission establishes an irreducible local background that overtakes the strongly attenuated extragalactic isotropic gamma-ray background. Our results demonstrate that the Galactic stellar ensemble is a strictly sub-dominant background, indicating that stellar subtraction templates are not required for identifying Galactic PeVatrons or constraining dark matter annihilation.

In order to model astrophysical environments characterized by radial stratification, such as supernova remnants or expanding superbubbles; correctly understanding the transport of non-thermal particles in astrophysical plasmas is essential. While large-scale Galactic propagation codes exist, they are often optimized for Cartesian or cylindrical geometries and lack the efficiency of one-dimensional spherically symmetric problems. In this work, we present SAETASS (Solver for Astroparticle Equation of Transport Analysis in Spherical Symmetry), a novel, open-source numerical tool designed to solve the time-dependent transport equation for astroparticles. The solver is built upon a conservative finite-volume framework that ensures exact particle conservation and numerical stability. To manage the interplay between diverse physical processes, SAETASS employs a modular operator-splitting architecture. Radial advection and continuous momentum losses are treated using a second-order, shock-capturing MUSCL-Hancock scheme, while the diffusive operator is integrated via an implicit, batched Crank-Nicolson algorithm. This approach allows for the robust handling of steep gradients, spatial discontinuities and regularity conditions at the origin. We rigorously validate the code through a suite of tests for pure advection, diffusion and losses. Finally, we demonstrate the solver's capabilities by modelling cosmic-ray proton transport in a real astrophysical scenario. Our results successfully recover established steady-state limits while revealing relevant pre-equilibrium temporal dynamics across Kolmogorov, Kraichnan and Bohm diffusion regimes. SAETASS provides the community with a lightweight, flexible tool for investigating particle acceleration and propagation in complex, radially dependent astrophysical environments.

Models predict that chemical enrichment and gas redistribution should begin rapidly once star formation starts, but direct constraints at the earliest epochs have been scarce. Here we show that metal-enriched gas in multiple ionic phases was already present around galaxies before the midpoint of cosmic reionization. Using JWST/NIRSpec rest-frame ultraviolet spectroscopy from SPURS, we detect blueshifted metal absorption in three galaxies at $7.2<z<9.3$. The detected transitions span neutral, low-ionization, and high-ionization species, including O I, Si II, C II, Si IV, and C IV, with velocity offsets of $|\Delta v|\sim 50$--$250\,\mathrm{km\,s^{-1}}$ relative to nebular systemic redshifts. The ionic coexistence, overlapping velocity structure, and equivalent-width ratios are consistent with outflowing or otherwise kinematically disturbed galaxy-associated gas, implying rapid metal enrichment. These results show that key conditions for baryon cycling were established in at least a subset of luminous galaxies within the first several hundred million years of cosmic time, well before the completion of reionization.

In transiting planetary systems, in which planetary sizes are accurately determined from transit observations, the presence of transit-timing variations (TTVs), especially when combined with radial velocity (RV) data, provides powerful constraints on masses and orbital eccentricities. Together, these measurements offer crucial insights into system architecture, formation mechanisms and dynamical evolution. We present long-term RV and transit/TTV monitoring of the relatively young star (age approximately 1 Gyr) TOI-201, revealing an exceptional multi-planet system composed of a hot super-Earth (SE) size planet transiting every 5.8 days, a warm Jupiter (WJ) on a 53-day orbit and an eccentric (e = 0.62) low-mass brown dwarf (BD) on an approximately 8-year orbit, with an estimated mass of about 16 Jupiter masses. The BD is the longest-period transiting substellar object ever characterized by means of RVs and the only one known to be coplanar with inner planets. The architecture of this system suggests that the SE was formed isolated and in the innermost region of the gaseous disk. On the other hand, the orbital configuration of the outer companions suggests a nearly in situ formation of both objects, with the WJ forming in a dense inner disk. Alternatively, the BD might have formed farther out and migrated inward, while increasing its eccentricity owing to interactions with the disk.

Galactic magnetic fields regulate star formation and cosmic-ray (CR) transport, and understanding their three-dimensional structure, particularly in star-forming late-type galaxies, is key to constraining galactic CR transport. We explore the validity of stacking Stokes $Q$ and $U$ spectra, to infer about the intrinsic polarisation characteristics of star-forming galaxies. To prepare the stacking experiment, we align, scale, convolve, and reproject $C$-band (6 GHz) Stokes $Q$ and Stokes $U$ cubes of 27 star-forming late-type edge-on galaxies. On the stacked cubes, we perform RM-synthesis and discuss the derived polarised intensity (PI), polarisation angle ($\chi_0$), and RM maps. Synthetic data tests demonstrate that stacking Stokes $Q$ and $U$ spectra is valid for tightly constrained underlying distributions of PI, $\chi_0$, and RM. For underlying PI, $\chi_0$, and RM distributions that represent star-forming galaxies, stacking introduces a systematic uncertainty of $\delta_\mathrm{RM}^\mathrm{sys}=90 \mathrm{rad m^{-2}}$ and significantly underestimates the recovered PI. Stacking results reveal a clear X-shaped pattern in the polarisation plane, consistent with prior findings, detecting polarised emission up to 9 kpc above the galactic disc. We find stronger PI on the approaching side of galaxies. Furthermore, we find a decrease in PI in the galactic halo of $\sim 60$% near the galaxy's minor axis. A global RM pattern, as reported in a previous study, cannot be confirmed. Based on our analysis, we present stacking of Stokes $Q$ and Stokes $U$ cubes as an effective tool to recover faint polarised emission in the halo of nearby galaxies, if the underlying distributions of PI, $\chi_0$, and RM are tightly constrained. Our findings motivate future studies using broader-band data to increase the resolution in Faraday depth.

We identify a systematic distortion of the gain-vs.-frequency function of radio telescopes caused by digital flattening ("whitening") of the signal's spectrum followed by re-quantization, a common pair of processes in the signal processing of modern telescopes. Wide-bandwidth telescopes often have a large variation of signal power over frequency. Flattening of the spectrum allows samples of the channelized signal to be represented in a small number of bits, allowing efficient downstream processing. However, we show that this produces subtle systematic error in the measured spectra. We explore this effect in data from the Owens Valley Radio Observatory's Long Wavelength Array (OVRO-LWA) and through detailed semi-analytic simulations. Although the effect can be small so that it has heretofore been unrecognized, we demonstrate that it produces distortion of the spectrum at a level that is problematic for some science, in particular 21 cm cosmology. Finally, we explore mitigation strategies, showing that the effect can be substantially reduced by careful choice of the gain distribution along the signal path or by incorporating dithering in the re-quantization step.

This chapter reviews applications of machine learning (ML) to redshifted 21 cm cosmology, focusing on cosmic dawn, the Epoch of Reionization, and SKA-Low science. The redshifted 21 cm line directly probes diffuse neutral hydrogen, but the measured signal is not a simple astrophysical observable: density, ionization, heating, radiation backgrounds, foreground treatment, and instrumental response are coupled. The chapter first summarizes the physical ingredients needed in later sections, including the global signal, spatial fluctuations, morphology-sensitive statistics, and the 21 cm forest. It then discusses the main barriers to interpretation: bright foregrounds, radio-frequency interference, ionospheric and calibration effects, incomplete sampling, and the cost of forward modeling in high-dimensional parameter spaces. ML applications are organized by their role in the analysis chain. Observation-domain methods act on contaminated data products; theory-domain methods accelerate or compress forward modeling; and inference-domain methods connect observables to astrophysical and cosmological parameters.

Mildly recycled pulsars are neutron stars partially spun up through relatively short mass-transfer phases, typically with massive carbon-oxygen (CO) or oxygen-neon-magnesium (ONeMg) white dwarf companions. PSR J2338+4818, a mildly recycled pulsar, was discovered with the Five-hundred-meter Aperture Spherical Telescope (FAST). As a pilot study on the formation and evolutionary pathways of mildly recycled pulsars, we present the updated timing solution for PSR J2338+4818 and examine its single pulses and scintillation properties. Aided by the sensitivity of FAST, the single pulses of PSR J2338+4818 were systematically studied. 27,228 single pulses with S/N > 7 have been detected in our observations. For the FAST ultra-wideband observation on MJD 61045, the receiver was still in the technical commissioning phase, and then only a preliminary single-pulse search was performed. Pulse nulling was examined using a Markov Chain Monte Carlo (MCMC) method, but no evidence for nulling was found. The possible long-term nulling reported by previous studies did not occur in any of our observations in either the 1.0 to 1.5 GHz band or the 300 to 600 MHz band. Interstellar scintillation is evident in our observations. The measured scintillation timescales and bandwidths range from 2.93 to 25.26 minutes and 1.68 to 27.41 MHz, respectively. In all observations, no clear scintillation arc was found in the secondary spectra of PSR J2338+4818.

(Abridged) We aim to explore the parameters that influence the mid-infrared emission of C$_2$H$_2$ and H$_2$O, and if the spread observed in $F\rm{_{C_2H_2}}$/$F\rm{_{H_2O}}$ is tracing a variation of the C/O ratio. Our work is based on the DALI 2D thermochemical model to predict spectra readily comparable to JWST/MIRI observations. To robustly model organics in inner disks, several improvements have been made: (1) carbon chemistry adapted for warm environments, (2) updated UV shielding treatment, and (3) mutual line overlap in the raytracing. We are able to reproduce the observed C$_2$H$_2$ fluxes of T Tauri disks with a solar C/O ratio. Acetylene abundance is primarily set by a balance between formation initiated by CO dissociation by X-rays and destruction of carbon chains by atomic oxygen, the latter being generated by X-ray-induced destruction of H$_2$O and CO. The water UV shielding and hot temperatures of the inner disk also favor acetylene formation, as they prevent the destruction of carbon chains and allow overcoming activation barriers of reactions with H$_2$. C$_2$H$_2$ and H$_2$O emissions are not only sensitive to the C/O ratio but also to the total O/H elemental abundance, supporting recent claims. In particular, we find that enhanced O/H reduces acetylene emission due to an excess of atomic oxygen. $F_{\rm{C_2H_2}}$/$F_{\rm{H_2O}}$ is thus a promising tracer of the elemental composition of inner disks. Still, the dust size distribution also plays a key role in this line flux ratio. We find that increasing the abundance of small grains relative to large grains favors C$_2$H$_2$ flux over H$_2$O flux. Grain depletion does not affect the line flux ratio as previously suggested by observational works. A preliminary comparison with published JWST observations indicates a gas-phase C/O ratio below unity and suggests that enhanced O/H ratios may be common in T Tauri disks.

O-C timing analysis is a useful diagnostic tool for quasi-periodic eruptions (QPEs), but their interpretation depends sensitively on the integer cycle number assigned to each eruption. In this note, we show that even a small mismatch in the cycle number, $N_{\rm cyc}$, can produce large false signals in O-C diagrams, and \emph{a universal feature of these false signals is a large in-phase sinusoidal modulation between even and odd eruptions.} Therefore, uncertainties in $N_{\rm cyc}$ must be inferred or marginalized over before physical interpretations are attached to O-C. We then apply both O-C and EMRI+disk to GSN 069 and eRO-QPE2. For GSN 069, the timing data favor an anti-phase modulation in even and odd eruptions, consistent with apsidal precession in a low-eccetricity EMRI crossing an equatorial disk. For eRO-QPE2, the data are well described by a near-circular EMRI and a precessing disk.

While recent JWST observations of mature super-Earths and sub-Neptunes have frequently revealed featureless transmission spectra, their inflated progenitors offer a unique window into understanding their primordial compositions. As part of the Keys to Revealing the Origin and Nature Of sub-neptune Systems (KRONOS) JWST program, we present the NIRISS/SOSS transmission spectrum of V1298 Tau c, a $\sim$23 Myr super-Earth progenitor orbiting a young Solar analog. We detect H$_2$O in V1298 Tau c's atmosphere with a $\log_{10}$ volume mixing ratio of $-1.83^{+0.68}_{-0.77}$, but no additional molecules from these data alone. We find consistent results for the planetary atmospheric properties in both retrievals with and without informed priors on stellar heterogeneities based on the observed stellar spectrum. We infer an atmospheric metallicity [O/H] of $14.8^{+56.0}_{-12.28}\times$ the solar value. This metallicity is similar to literature measurements for other young planets, including its massive outer companion V1298~Tau~b. In contrast, this measured metallicity is systematically lower than the metallicities of mature planets of similar mass and temperature. Altogether, these results provide tentative but growing evidence that the exoplanet mass--metallicity relation evolves with planetary age.

We investigate UV absorption lines tracing cool gas in eight bright ($-21.9<M_\mathrm{UV}<-20.5$) galaxies at $z=7.2-10.6$ using deep JWST/NIRSpec medium-resolution spectra homogeneously selected from archival data. We identify multiple absorption lines of low-ionization species (LIS) in five galaxies, while the remaining three show only one or no significant detections. The average LIS equivalent widths $\mathrm{EW_{LIS}}$ indicate weaker absorption lines in compact ($r_\mathrm{e}\lesssim 100$ pc) galaxies with high $L_\mathrm{H\beta}/L_\mathrm{UV}$ and $\Sigma_\mathrm{SFR}$, suggestive of absorption-line suppression due to intense star formation or nuclear activity. We simultaneously fit multiple LIS lines, accounting for both covering fraction $C_f$ and column density $N$, and find that the five galaxies follow the local $C_f$-$N$ relation. Through the LIS-line fitting, we derive chemical abundance ratios. The five galaxies have abundance ratios similar to those of damped Ly$\alpha$ (DLA) systems in the [Si/O]-[C/O] and [Fe/Si]-[Al/Si] planes, suggesting that their absorbing gas is similar to that of DLAs. We find that two galaxies at $z\sim 7$ are already highly Fe-enriched, with $\mathrm{[Fe/Si]}\simeq -0.2$, near the solar abundance ratio. While the high Fe enrichment may originate from early Type-Ia supernovae (SNe Ia) or pair-instability supernovae (PISNe), these two galaxies also show $\mathrm{[Al/Si]}\sim0$, with no signature of the strong odd-even effect expected from PISNe, favoring SNe Ia.

With the commissioning of the James Webb Space Telescope (JWST), near- and mid-infrared observations are rapidly extending into the wavelength regime where emission from small dust grains in circumplanetary disks (CPDs) is expected to dominate. We aim to systematically investigate how individual physical parameters of CPDs shape their infrared spectra and to improve the robustness of spectral fitting and physical interpretation of current and future observations. Building on our previous parametric CPD models, we employ a parameter-grid approach combined with radiative transfer simulations to explore the dependence of observable spectra on disk structure and dust properties. We identify the physical mechanisms responsible for the main spectral features and parameter degeneracies, and present the global trends emerging from the parameter study. We also demonstrate the applicability of the models by fitting representative observational data. Our results provide a structured theoretical framework for interpreting near- and mid-infrared observations of CPDs with JWST and related facilities.

We investigate how tidal locking affects the magnetic field generation and magnetospheric protection of Earth-like planets orbiting the habitable zone of M dwarfs. While the role of stellar activity has been widely studied, the impact of tidal locking on the planetary dynamo remains largely unexplored. We develop a framework that couples the stellar wind with two distinct dynamo paradigms: direct rotational scaling of a dipolar field, and energy-flux scaling where the local Rossby number governs the magnetic geometry, capturing a rapid transition from a dipolar to a multipolar configuration. We employ a Constant Time Lag model to capture the continuous tidal spin-down of the planets, evaluating two distinct planetary interiors: a highly dissipative Modern Earth and a less dissipative, rapidly rotating Early Earth. We find that tidal locking acts as a severe negative feedback on planetary magnetism across both paradigms, where the dipolar field frequently collapses before full tidal synchronization is reached. At the inner boundary, nearly all the planets are rapidly locked and the intrinsic magnetic fields are significantly attenuated. The outer boundary provides a favorable environment only for early M dwarfs ($M_\star \gtrsim 0.32~M_\odot$) hosting Early Earth. Here, the combination of non-synchronous rotation and residence outside the sub-Alfvénic regime provides atmospheric protection likelihoods of $97-100\%$. For mid-to-late M dwarfs, the combination of inevitable tidal locking and a sub-Alfvénic environment results in a total collapse of the magnetic shield, reducing the likelihood of atmospheric protection to essentially zero across the entire habitable zone.

The cosmic-ray ionization rate (CRIR) is one of the fundamental parameters influencing the chemical and dynamical evolution of molecular clouds. Although observations in recent years have revealed high CRIR values in massive star-forming regions and in the vicinity of protostars, the sources and acceleration mechanisms of cosmic rays remain uncertain. In this work, we present our new estimates of CRIR using the HI narrow self-absorption (HINSA) technique towards two nearby low-mass star-forming clouds, IC 348 and NGC 1333. In both clouds, the CRIR decreases with increasing H$_2$ column density, but IC 348 exhibits values that are roughly an order of magnitude higher than those in NGC 1333. To interpret this contrast, we model the low-energy spectrum of CRs in a finite slab attenuation framework, using additional constraints from the high-energy CR spectrum inferred from Fermi $\gamma$-ray observations. The best-fit spectra reproduce the observed CRIR profiles and the contrast between IC 348 and NGC 1333 suggests an order of magnitude difference in low-energy CR populations, likely originating from local acceleration sources beyond protostars (e.g., stellar-wind termination shocks), and partly from the same sources responsible for the GeV $\gamma$-ray excess. Although uncertainties in cloud structure and gas density may affect the absolute CRIR values, they do not erase the pronounced disparity between the two regions.

Ionized bubbles around the first galaxies link early galaxy growth, ionizing photon escape, intergalactic-medium topology, Ly{\alpha} visibility, 21 cm structure, and the timing of reionization. With JWST now constraining both the abundance of luminous galaxies at $z\gtrsim 10$ and rare Ly$\alpha$ emitters deep in the neutral era, it is timely to ask how often galaxy populations produce large ionized environments. We model the incidence of galaxy-driven ionized bubbles at $z\approx 13$ using JWST UV luminosity functions, taking the Ly$\alpha$ source reported by Witstok et al. (2025) as a benchmark for the relevant bubble scale. We quantify the incidence of regions with comoving radius $R\ge 2.5$ cMpc through the sky surface density $\Sigma_{\ge 2.5}$ at $z\approx 13$. For our fiducial case (UVLF from Donnan et al. 2024 with $f_{\mathrm{esc}}=0.2$, $\log\xi_{\mathrm{ion}}=25.5$, $f_{\mathrm{duty}}=1$, and $C=3$), we find $\Sigma_{\ge 2.5}\simeq 1.33\times 10^{-2}$ arcmin$^{-2}$ per $\Delta z=1$. Because bubbles are treated as independent spheres with random source positions and no union of overlaps, this is a conservative baseline for the abundance of connected ionized environments. We conclude that Witstok-sized regions are plausible in UVLF-calibrated galaxy-driven models. This is a population-level statement, however, and the specific Witstok source may still require unusual effective ionizing efficiency, recent fading or burstiness, or a non-stellar ionizing contribution.

We present spatially resolved spectroscopy with JWST/MIRI MRS of a representative sample of normal star-forming galaxies at $z\sim1.1$ as part of the PAHSPECS program. To extract emission from Polycyclic Aromatic Hydrocarbon (PAH) features, we forward model the data cubes with non-parametric spatial distributions, accounting for convolution with the PSF. With this method we are able to recover accurate spatial profiles of the 3.3 $\mu$m, 6.2 $\mu$m, 7.7 $\mu$m, 11.3 $\mu$m PAHs and [ArII] (6.98 $\mu$m) emission and produce PAH ratio maps at cosmic noon. From the PAH ratio maps we find that PAHs become larger and more neutral with increasing galactocentric radius, which is the opposite of trends in local galaxies, indicating radial ISM gradients in normal star-forming galaxies are different at cosmic noon. Through spatially resolved SED fitting of HST and JWST photometry we measure the UV radiation field hardness through the intrinsic ratio of UV to optical flux and find the 3.3/11.3 PAH ratio to decrease with increasing hardness and the 11.3/7.7 to increase. This may suggest photo-destruction of small/ionized PAHs is driving the observed PAH ratio trends and may explain the overall lower 3.3/11.3 PAH at cosmic noon compared to the local universe. This work demonstrates that PAH properties hold crucial information on the resolved ISM physics of galaxies at cosmic noon.

We present CMBComp, a compact and accurate compressed cosmic microwave background (CMB) likelihood that captures the dominant geometric information of the full CMB likelihood derived from the combined SPT-3G D1 + ACT DR6 + Planck PR3 primary CMB anisotropy + Planck PR4/NPIPE CMB-lensing dataset, which we collectively refer to as SPA. The compression is fast to evaluate and trivial to implement in standard inference pipelines. We construct and validate it in five model spaces: the spatially flat cosmological-constant model ($\Lambda$CDM), and its dynamical-dark-energy ($w_0w_a$CDM), massive-neutrino ($\nu\Lambda$CDM), non-flat ($o\Lambda$CDM), and joint massive-neutrino--dynamical-dark-energy ($\nu w_0 w_a$CDM) extensions. Five compressed likelihoods are introduced, corresponding to two three-parameter compressions for the dark-energy sector (CMB-3 for $\Lambda$CDM and CMB-3w for $w_0w_a$CDM), two four-parameter compressions for the neutrino sector (CMB-4$\nu$ for $\nu\Lambda$CDM and CMB-4$\nu$w for $\nu w_0 w_a$CDM), and a four-parameter curvature compression (CMB-4k for $o\Lambda$CDM). Combining each compressed likelihood with the DESI DR2 baryon acoustic oscillation (BAO) data, we demonstrate that the resulting posteriors agree to high precision with those obtained from the corresponding full-CMB chains. CMBComp is therefore particularly well suited to cosmological inference for models that modify the late-time expansion history, enabling accurate CMB constraints to be incorporated into new analyses with minimal computational overhead and without reliance on a full Boltzmann-solver-based inference pipeline. The compressed likelihood files and example notebooks accompanying CMBComp are made publicly available at this https URL.

Evaluating the performance metrics of theta-phi robotic positioners is crucial to gather insights into the system's behavior and ensure their reliability during operation in Stage-5 telescopes such as the Chinese MUST, the American Spec-S5 and the European WST. With a careful analysis of these metrics, a comprehensive characterization of the system's strengths is obtained, alongside a clear identification of aspects requiring improvement. Thus, providing potential avenues for streamlining and optimizing its design and functionality. In this paper we present the results of the positioning performance and angular tilt tests conducted on 6.2-mm pitch robotic positioner modules developed for high-density fiber positioning in next-generation astronomical systems. The fiber positioners from the tested prototype adopt a mechanical design based on the Trillium open design from the Lawrence Berkeley National Laboratory (LBNL) and were produced by the Japanese company Orbray. The evaluated performance metrics of positioning repeatability, datum repeatability, backlash, non-linearity, and angular tilt were measured and compared to the desired performance for Stage-5 telescopes. The positioners exhibited a generally acceptable performance, although noticeable anomalies affecting several metrics were identified and will require mitigation in subsequent prototypes. Nevertheless, the results indicate promising performance suitable for Stage-5 telescope instrumentation, provided that these issues are successfully resolved.

Strong lensing observations of the Bullet Cluster have traditionally been regarded as strong evidence for dark matter and a major challenge to Milgromian dynamics (MOND). The offset between the lensing mass and the X-ray gas centroids implies a substantial amount of unseen mass near the brightest cluster galaxies (BCGs). However, the high metallicities observed in both the intracluster gas and the massive early-type member galaxies suggest a past stellar population dominated by massive stars, whose evolved remnants contribute additional baryonic mass. This effect is naturally incorporated in the integrated galaxy-wide initial mass function (IGIMF) theory, which predicts substantially larger baryonic masses than a canonical IMF. In this work, we re-estimate the baryonic masses of the three BCG-centred core regions of the Bullet Cluster using recent JWST photometry and compare them with MOND strong-lensing masses. We derive IGIMF masses using stellar population synthesis models with constant and (self-) enriched metallicities, representing lower and upper mass limits, respectively. We find that the MOND strong-lensing masses of all three cores lie within the range predicted by the IGIMF models. These results suggest that the baryonic mass budget is consistent with MOND requirements from strong-lensing observations in the core regions of the Bullet Cluster. However, the physical viability of this scenario also depends on the spatial distribution and dynamical behavior of the remnant population, which remain to be established. More generally, regardless of the validity of MOND, the results imply that less dark matter may be required than previously inferred.

Standard weak-lensing calculations treat lensing as a linear remapping of the matter field along the line of sight. We instead formulate lensing as a stochastic field theory for the Sachs optical scalars, driven by random Ricci-focusing and Weyl-shearing fields. The resulting path integral generates a diagrammatic expansion for arbitrary $n$-point correlation functions of lensing observables, organised into linear response, nonlinear propagation, and driving-field cumulants. The conventional calculation emerges as the lowest-order, linear-propagation limit. Beyond it, nonlinear Sachs evolution couples to driving-field non-Gaussianity, mixing the matter cumulant hierarchy into the lensing hierarchy. A selection rule governs the couplings: an $n$-point observable receives a direct contribution from the $n$-point driving-field cumulant, and its leading hierarchy-mixing correction from the $(n+1)$-point cumulant via one nonlinear Sachs interaction, with higher cumulants entering only at higher order. The two-point function, for instance, is corrected by squeezed three-point cumulants of Ricci focusing and Weyl shearing, letting small-scale modes source larger scales and feeding the lensing $E$- and $B$-modes equally. Rather than a restrictive approximation scheme, the formalism is a paradigm shift: a unified framework naturally accommodating path corrections, higher-order matter statistics, stochasticity, and small-scale effects.

This paper is motivated by recent works on inverse problems for acoustic wave propagation in the interior of gas giant planets. In such planets, the speed of sound is isotropic and tends to zero at the surface. Geometrically, this corresponds to a Riemannian manifold with boundary whose metric blows up near the boundary. Here, the spectral analysis of the corresponding Laplace-Beltrami operator is presented and the Weyl law is derived. The involved exponents depend on the Hausdorff dimension which, in the supercritical case, is larger than the topological dimension.

Newtonian and post-Newtonian (PN) calculations suggest that each spherical harmonic mode of the gravitational waveforms (radiation) emitted by eccentric binaries can be further decomposed into several eccentricity-induced modes (indexed by $j=1$ to $j=\infty$), referred to as eccentric harmonics. These harmonics exhibit monotonically time-varying amplitudes and instantaneous frequencies, unlike the full eccentric spherical harmonic modes. However, computing or extracting these harmonics are not straightforward in current numerical relativity (NR) simulations and eccentric waveform models. To address this, Patterson \textit{et al} have developed a framework to extract the eccentric harmonics directly from effective-one-body formalism waveforms. In this paper, we build on the ideas presented in Patterson \textit{et al} and propose a data-driven framework, utilizing singular-value decomposition (SVD), that incorporates additional features based on PN intuition to ensure monotonicity in the extracted harmonics. We further demonstrate that the phase (frequency) of these harmonics is simply $j\phi_{\lambda}+\phi_{\rm ecc}$ ($jf_{\lambda}+f_{\rm ecc}$) where $\phi_{\lambda}$ ($f_{\lambda}$) is related to the secular orbital phase (frequency) and $\phi_{\rm ecc}$ ($f_{\rm ecc}$) is an additional phase (frequency) that only depends on the eccentricity. We also provide simple analytical fits to obtain the harmonics as a function of the mean anomaly. These relations may prove useful in constructing faithful models that can be employed in cheap and efficient searches and parameter estimation of eccentric mergers. Our framework is modular and can be extended for any other eccentric waveform models or simulation frameworks. The framework is available through the \texttt{gwMiner} package.

We present a comprehensive analysis of the interactions of neutrinos with the dark sector within the simplified model framework. We first derive the exact analytic formulas for the differential scattering cross sections of neutrinos with scalar, fermion, and vector dark matter (DM) for light dark sector models with mediators of different types. We then implement the full catalog of constraints on the parameter space of the neutrino-DM and neutrino-mediator couplings and masses, including cosmological and astrophysical bounds coming from Big Bang Nucleosynthesis, Cosmic Microwave Background, DM and neutrino self-interactions, DM collisional damping, and astrophysical neutrino sources, as well as laboratory constraints from 3-body meson decays and invisible $Z$ decays. We find that most of the benchmarks in the DM mass-coupling plane adopted in previous studies to get an observable neutrino-DM interaction effect are actually ruled out by a combination of the above-mentioned constraints, especially the laboratory ones which are robust against astrophysical uncertainties and independent of the cosmological history. To illustrate the consequences of our new results, we take the galactic supernova neutrinos in the MeV energy range as a concrete example and highlight the difficulties in finding any observable effect of neutrino-DM interactions. Finally, we identify new benchmark points potentially promising for future observational prospects of the attenuation of the galactic supernova neutrino flux and comment on their implications for the detection prospects in future large-volume neutrino experiments such as JUNO, Hyper-K, and DUNE. We also comment on the ultraviolet-embedding of the effective neutrino-DM couplings.

Cavity optomechanical systems have recently been proposed as detectors for ultralight dark matter, leveraging their ability to cool and probe mechanical oscillators at the quantum limit. Here we present a resonant search for ultralight dark matter using a cavity optomechanical accelerometer. The detector consists of a cryogenic Si$_3$N$_4$-membrane cavity mounted to a 4 K copper plate, with photothermal tuning used to scan its 39 kHz mechanical resonance. Shot-noise-limited displacement readout and radiation-pressure feedback cooling yield an acceleration sensitivity of $\sim 10\;\text{n}g_0/\sqrt{\text{Hz}}$ over 30 Hz near resonance. The detector's material inhomogeneity gives access to direct vector coupling to the dark-matter field. We conduct a resonant search based on matched-filter statistics, yielding upper bounds consistent with thermal noise and above those set by equivalence principle tests. No signal is observed, but the experiment demonstrates stable, quantum-limited operation and validates a scalable approach to resonant detection. With optimized test masses, lower temperature, and multiplexed arrays, the platform offers a path toward competitive constraints on vector-mediated dark-matter interactions.

We analyze a generalized framework of smooth F-term hybrid inflation (smFHI) consistent with gauge coupling unification within the Minimal Supersymmetric Standard Model (MSSM). The embedding of the model in two specific Supergravity settings addresses at the same time the $\eta$ problem and the compatibility with the recent ACT or SPT data. The one relies on the choice of a shift-symmetric Kähler potential for the inflaton which revitalizes the SUSY predictions of smFHI, whereas the other employs a Kähler potential associated with an hyperbolic Kähler manifold. An essential role in both our constructions is played by a decoupled superheavy field without superpotential and Kaehler potential inspired by string- and D-brane--based models. Our proposal can be realized for a variety of representations for the Higgs fields involved in smFHI and assures monotonic inflationary potential.

The Parity-Doublet Model (PDM) is a chirally invariant effective theory for strong-interaction matter involving nucleons and their opposite-parity partners in a parity-doubling framework. We introduce a multiplicatively renormalizable mean-field approach to include the baryonic vacuum contributions to the resulting grand-canonical potential in an explicitly renormalization-group invariant form. As an application, we evaluate the pertinent thermodynamics of two-flavor symmetric and asymmetric nuclear matter, focusing on the restoration of spontaneously broken chiral symmetry at baryon densities and temperatures relevant for the astrophysics of neutron stars. Special attention is paid to the effect of the baryonic vacuum fluctuations on the evolution of the chiral condensate with baryon density and temperature for specific choices of the chirally invariant baryon mass m0 to demonstrate the importance of consistently including these vacuum fluctuations in the PDM.

In this paper we discuss how the Cosmic Neutrino Background can affect the measured phase difference in a matter interferometer. This phase is proportional to a difference in potential energies along the two interferometer paths. The relevant potentials here are the well-known neutrino matter potential and a potential related to the Stodolsky effect. We show how they can be rewritten in terms of scalar potentials, pseudo magnetic fields and spin-spin interactions. Unfortunately, current technology is unlikely to detect this effect and we discuss prospects for the future. We also briefly comment on fermionic Dark Matter which can give rise to very similar effects which can easily be larger than the neutrino case.

The dark bubble model makes a positive cosmological constant natural in string theory, and predicts several new physical phenomena within reach in the near future. In this paper we study the experimental consequences of the model for the strength of gravity at scales of order $10^{-5}$m. Contrary to other models of gravity involving extra dimensions, the dark bubble model predicts gravity to become weaker rather than stronger at small scales, compared to Newtonian gravity. In particular, we provide explicit predictions of measurable deviations using table top experiments. We also show how the same effect reduces the effective force of gravity at high energy densities in cosmology, leading to a period of early inflation without the need for anything beyond radiation. We also discuss the quantum origin of the universe with a 5D black hole acting as a catalyst for the nucleation of the dark bubble and how it accounts for the present matter content in the universe. This leads to a prediction of $\Omega_c \approx 5\times 10^{-4}$ for a positive curvature of the universe, suggesting an explanation of the why-now-problem of the cosmological constant. We end by speculating on how to incorporate AdS black shells as black hole mimickers within the dark bubble model.

This study evaluates the capability of future multi-band observations of gravitational waves emitted from binary black hole coalescences, utilizing joint third-generation ground-based (CE, ET) and space-based (LISA, Taiji, TianQin) detector networks, to constrain parity and Lorentz symmetry violations in the gravitational sector. We model these effects through a parameterized waveform framework that incorporates a set of parameters that quantify potential deviations from general relativity. The frequency-dependence of their effects is described by power-law indices $\beta$ (i.e., $\beta_{\bar \nu}$, $\beta_{\bar \mu}$, $\beta_{\nu}$, and $\beta_{\mu}$). By analyzing events such as a high-signal noise ratio (SNR) "golden event" like GW250114 and a massive binary system like GW231123 (total mass $190-265 M_\odot$) using two networks of ground- and space-based detectors, we demonstrate that multi-band observations can significantly improve the current constraints on Lorentz and parity violations by several order of magnitude, for both high-frequency ($\beta > 0$) and low-frequency ($\beta < 0$) modifications. Our Bayesian analysis reveals that while the exceptional SNR of the GW250114-like event yields superior constraints for high-frequency modifications ($\beta > 0$), the massive nature of GW231123 provides more stringent limits for low-frequency effects ($\beta < 0$). This work highlights the critical value of future multi-band gravitational wave astronomy for conducting precision tests of general relativity across diverse binary populations.

Three-nucleon force (3NF) plays an important role in understanding the structure of finite nuclei and the saturation properties of infinite nuclear matter. More specifically, 3NF should be necessary for each two-nucleon force (2NF) to obtain more accurate description of nuclear systems. 3NF derived from the chiral effective field theory has been successful in $\textit{ab initio}$ calculations of atomic nuclei. Most of established chiral nuclear forces have a nonlocal form in the momentum space. In this work, we construct a companion chiral 3NF specifically tailored to the new Idaho local position-space 2NF, and calculate binding energies and radii of nuclei up to $^{132}$Sn. We find that a chiral 3NF with hybrid local and nonlocal regulators has advantages in improving the nuclear structure calculations of both binding energies and radii with the new Idaho 2NF. The two low-energy constants of 3NF are constrained by the ground-state energies of $^3$H and $^{16}$O as suggested in a recent work.

Unidentified Falling Objects (UFOs) refer to sporadic beam losses observed during LHC operation. The prevailing explanation is that micrometer-sized dust particles released from the beam screen produce beam losses through interactions with the protons. However, the release mechanism of these particles remains unknown. We propose that roughly $(1-10)$% of UFOs may be caused by axion quark nuggets (AQNs), macroscopic dark matter (DM) candidates with masses of order $(5-1000)\,$g. The AQN model naturally relates the dark- and visible-matter abundances ($\Omega_\mathrm{DM}\sim\Omega_\mathrm{visible}$) and provides a mechanism for generating the baryon-antibaryon asymmetry, with DM composed of both matter and antimatter AQNs. When passing underground within approximately 100km of the LHC, an antimatter AQN generates acoustic waves strong enough to trigger multiple UFO events within $2\,$s. If three correlated UFOs (placed at different locations along the LHC ring) are detected, the signal-to-noise ratio can exceed 5 across the entire allowed AQN mass range for a measurement time of about 360 hours. Practically, the LHC can serve as a large broadband acoustic detector for AQNs.

Typical gravitational production of relics from amplification of inflationary perturbations assumes Bunch-Davies initial conditions, i.e. a vacuum with initially no particles. In this paper we investigate the impact of non Bunch-Davies initial conditions to the final abundance of relics, with particular attention to the parameter space where the total dark matter abundance is reproduced. We present a general framework for any initial condition, through which we show their non-trivial effect on both spectrum and late-time abundance. We argue that for particles whose source of conformal symmetry breaking comes only from a mass term (spin-1/2 fermions and conformally coupled scalars), the choice of initial conditions has little impact on the mass range relevant to dark matter. For other particles, e.g. the longitudinal mode of spin-1, we see a large deviation from the standard computation. We exemplify and quantify our results with an initial thermal state and a two-stage inflation scenario, highlighting that the total dark matter can be obtained for a wide range of masses.

We show that, within a broad stationary-axisymmetric class, Kerr-type separability and hidden symmetry arise as a local consequence of the Einstein equations. Without assuming separability, algebraic speciality, Killing--Yano symmetry, or global boundary conditions, we analyze stationary and axisymmetric geometries in a locally non-rotating orthonormal frame and impose a minimal local equilibrium condition, namely the absence of mixed energy-momentum fluxes. We find that the mixed Einstein equations enforce a rigid projective alignment between radial and angular sectors, uniquely characterized by a constant-Schwarzian constraint. This constraint yields a universal classification of local solutions into Möbius, exponential, and trigonometric branches, of which global regularity selects precisely the Kerr-type sector. In this sense, the kinematical core of Kerr geometry is already fixed locally, and the Schwarzian structure provides the local origin of Kerr rigidity.

This work investigates the universality of cusp formation in the shadows of compact objects. The emergence of cusps is accompanied by three interrelated phenomena: a topological charge transition, an equal-area law governing the self-intersecting structure, and universal critical scaling behavior. We demonstrate that, because these phenomena originate from the global morphology of the shadow, they are fundamentally independent of specific spacetime metric details and apply across diverse models. These features are systematically analyzed for the Kerr black hole endowed with a running Newton coupling. By extending our framework to rotating traversable wormholes, we confirm that the same universal behavior persists in more general compact objects. Our study uncovers the universality underlying cusp formation, offering a model-independent framework for characterizing possible non-Kerr shadow morphologies.

We investigate baryogenesis in Standard Model (SM) extensions with new $SU(2)_L$ multiplet fields. We focus on sphalerogenesis, in which the baryon asymmetry of the Universe (BAU) is generated through the gradual decoupling of CP-violating electroweak sphaleron-like processes. We show that the observed BAU can be reproduced when the new fields possess CP-violating Yukawa interactions, which leave a CP-violating dimension-six operator involving the $SU(2)_L$ gauge fields at low energies. As representative examples, we study models with fermionic $SU(2)_L$ quintuplets and septuplets, and find that these field masses should be $\mathcal{O}(1)\,\mathrm{TeV}$ to explain the BAU. We also show that viable parameter regions for the BAU are consistent with current bounds on the electron electric dipole moment and thoroughly probed by future measurements such as ACME III and by mono-lepton searches at the HL-LHC. Our results provide a concrete and phenomenologically testable ultraviolet completion of sphalerogenesis.

The unique resonance features in the $^{12}$C+$^{12}$C fusion reaction lead to significant fluctuations in the branching ratio $R_{p/\alpha}=\sigma_p/\sigma_\alpha$, making it difficult to determine the $R_{p/\alpha}$ at astrophysical energies. By combining Hauser--Feshbach statistical-model calculations with constraints from direct charged-particle and gamma-ray measurements, we investigate the energy dependence of the averaged $R_{p/\alpha}$ and predict its behavior within the Gamow window. Owing to the strong energy dependence of $R_{p/\alpha}$, the corresponding reaction-rate ratios, $\langle \sigma v \rangle_p / \langle \sigma v \rangle_\alpha$, during core and shell carbon burning are determined to be 0.29, 0.45, and 0.52 at $T_9 = 0.5$, 1.0, and 1.2, respectively, significantly lower than the widely adopted CF88 constant value of 0.79. The implications of the revised $\langle \sigma v \rangle_p / \langle \sigma v \rangle_\alpha$ ratio for stellar nucleosynthesis and white-dwarf evolution are also discussed.

The microphysics underlying non-baryonic dark matter remains unknown. I derive the two-species Schrödinger-Poisson-Yukawa system for spin-1/2 dark-sector fermion fields, $\psi$ (mass $m_1$) and $\chi$ (mass $m_2$), coupled through a scalar mediator of mass $m_\phi$ via a universal Yukawa coupling, within an orbital-free density-functional framework with the Kirzhnits gradient coefficient $\lambda_B=1/9$. A central result is that the Bohm potential, far from being negligible in the Thomas-Fermi regime, contributes a species-dependent surface-energy correction analogous to the nuclear liquid-drop model: the heavier fermion species generates an outward quantum-pressure wall whilst the lighter species provides an inward surface tension, with degeneracy pressure furnishing the bulk confinement. In the single-species Schrödinger-Poisson limit the ground state recovers the benchmarked invariants $M_{\mathrm{dim}}\simeq 3.883$ and $x_T\simeq 2.562$, yielding $M R_T\simeq 9.95\,\lambda_B\hbar^2/(G m_1^2)$. For polytropic index $\gamma=5/3$ the mass-radius relation satisfies $R\propto M^{-1/3}$; for $\gamma=4/3$ a limiting mass emerges above which no stable equilibrium exists. Illustrative configurations span $M=10^{-8}$-$5\, M_\odot$, $m_1\sim 10^{-14}$-$10^{-6}\, eV$, and radii from a few~km to $\sim 10^3\, R_\odot$, with gravitational-wave contact frequencies in the Einstein Telescope and LISA bands and microlensing signatures accessible to current surveys. The predictive rigidity of the resulting mass-radius relation, in which the single microphysical parameter $m_1$ determines the equilibrium radius once the total mass is specified, furnishes a reproducible, first-principles reference for constraining the dark-fermion mass in multi-component dark sectors.

Much like the aerodynamic deflection of a spinning curveball, a rotating secondary in an extreme-mass-ratio inspiral (EMRI) experiences Magnus and lift forces, in addition to the standard drag force, when traversing a gaseous environment. We present the first framework that incorporates these specific spin-coupled environmental effects (EEs) into the evolution of EMRI. Over the multi-year observation windows of space-based gravitational-wave (GW) detectors, these interactions imprint a unique, distinguishable dephasing signature on the signal. Crucially, a Fisher matrix analysis reveals that gas drag breaks the fundamental vacuum-projection degeneracy between the secondary's spin magnitude and inclination, thereby tightening parameter constraints. Thus, accounting for EEs is not merely a modeling necessity, but could potentially be a powerful tool for enhancing the detectability of the secondary's intrinsic spin, and could serve as a novel probe of accretion flows harboring massive black holes.

We present $\tt BlackHawk$ $\tt v3.0$, a major update of the public code designed to compute Hawking radiation spectra of black holes. Building upon previous versions, this release considerably extends the range of black hole geometries that can be studied by implementing several new spherically symmetric metrics: the Bardeen and Hayward regular black holes, the Simpson-Visser and Peltola-Kunstatter black-bounces, the D'Ambrosio-Rovelli black hole-to-white hole metric, and the Babichev-Charmousis-Lehébel black hole. For each metric, we compute the corresponding Hawking temperatures and greybody factors, enabling the determination of primary Hawking emission spectra for particles of different spins. The greybody factors are obtained through dedicated numerical routines based on the companion code $\tt GrayHawk$. Additionally, $\tt BlackHawk$ $\tt v3.0$ introduces several technical improvements aimed at enhancing precision and efficiency, providing a highly versatile tool. The code is publicly available at this https URL