We investigate the origin and evolution of cosmic magnetic fields using a suite of large-volume cosmological magnetohydrodynamic simulations (L$_\mathrm{box}=25$ Mpc/h) run with the moving-mesh code AREPO. Atop the IllustrisTNG galaxy formation model, we implement additional recipes for magnetogenesis in which magnetic energy is injected during supernovae (SNe) and supermassive black hole (SMBH) feedback events, and compare these to simulations initialized with uniform primordial seed fields. Halo magnetic field strengths at $z=0$ are largely similar across seeding models and are primarily amplified and sustained by small-scale and halo-scale dynamo action. Nevertheless, we find differences in magnetic field topology, with SMBH-driven models exhibiting systematically smaller coherence lengths than primordial-only and SNe-only runs. We find that feedback-driven injection accelerates the onset of dynamo growth, leading to more rapid convergence of magnetic field strengths with numerical resolution, particularly in low-mass halos. In the intergalactic medium (IGM), SNe-only injection underproduces magnetic fields relative to inferred lower limits from $\gamma$-ray cascade constraints at both $z=0$ and $z \sim 3$, whereas our specific SMBH-based injection prescription satisfies present-day constraints but remains in mild tension at high redshifts. Reconciling these specific high-$z$ constraints therefore likely requires either modified feedback prescriptions or an additional primordial seeding component.

The cusp-core problem remains a key challenge for the $\Lambda$CDM model. Historically, comparing inner dark matter halo slopes ($d\log\rho/d\log r$) from simulations and observations has suffered from a methodological mismatch: evaluating slopes at different radii creates apparent tensions due to inconsistent definitions rather than genuine physical differences. We rigorously compare dark matter density profiles of Milky Way (MW) dwarf satellites inferred from dynamical modelling against CDM hydrodynamical simulations. Using the NIHAO and FIRE-2 suites ($M_{\star} \sim 10^3$-$10^{11}\,\rm M_\odot$), we confront simulated profiles with dynamical inferences of 16 MW satellites across four methods, strictly within their reliability limits. Crucially, we evaluate simulated slopes at observationally accessible radii, directly comparing profiles at matched stellar mass. Both observed and simulated galaxies exhibit a mass-dependent core-formation trend: inner slopes rise from cuspy values ($\approx -1.5$) at $M_{\star} \sim 10^5\,\rm M_\odot$ to core-like values ($\approx 0$ to $-0.4$) at $M_{\star} \sim 10^8\,\rm M_\odot$. Efficient core formation begins at $M_{\star} \gtrsim 10^6\,\rm M_\odot$ for centrals, where satellites display increased scatter consistent with tidal disruption. Simulated profiles agree with observations within $\lesssim 1\sigma$ for most systems, outperforming a NFW profile. Furthermore, differing observational models present scatter for a given system comparable to the simulation-to-observation offset. Evaluating dark matter density slopes at fixed physical radii significantly improves agreement between hydrodynamical simulations and dynamical models, revealing no clear tension when comparing profiles at fixed stellar mass, but Willman\,1 remains an unresolved outlier.

Early JWST/NIRCam surveys revealed a puzzling population of high-redshift massive galaxy candidates largely absent from previous rest-frame UV surveys. Spectroscopic follow-up has both confirmed and contested these candidates, whose potential overabundance may challenge traditional models of galaxy formation. In this study we evaluate the reliability of the photometric selections used to identify these candidates in observational data by applying them to galaxies in the TNG300 simulation with synthetic dust-attenuated photometry. Among the five observational selection criteria considered, we find that the selection presented by Pérez-González et al. is the most reliable and inclusive. Nevertheless, only 1 of the 18 galaxies at $z\sim5$ with $M_{\star} \geq 10^{11}~\mathrm{M_{\odot}}$ in the simulation satisfies this selection; the remaining 17 galaxies are on average $\sim0.5$ mag bluer than the color selection under the adopted dust model. We construct an improved JWST/NIRCam color-magnitude selection that provides a more complete census of massive galaxies at $z\sim5$ in TNG300 while excluding dusty, low-mass galaxies identified by criteria from the observational literature. We investigate the descendants of the most massive NIRCam-selected galaxies at $z=7,~4,$ and $2$ in TNG300, finding that they rarely evolve into the most massive galaxies by $z=0$. In general only the high-redshift massive galaxies that undergo substantial late-time ($z\lesssim0.2$) merger-driven growth become the most massive galaxies in the Universe today. Together these results suggest that current observational JWST/NIRCam selections are not identifying the most massive high-redshift galaxies, and caution against interpreting high-redshift massive galaxies as direct progenitors of the most massive galaxies at $z=0$.

We present observations of the 1991bg-like type Ia supernova (SN) 2023vjh, associated with the elliptical galaxy MCG+04-10-013. Its light-curve shape parameters ($\Delta m_{15}(B)=1.89 \pm 0.01$ mag and $s_{BV} = 0.45 \pm 0.03$), together with its spectroscopic evolution, place it firmly within the class of fast-declining, subluminous SNe Ia. The near-peak spectra show prominent features of Si II, Ca II, and Ti II, consistent with a cool photosphere, and place SN 2023vjh within the "cool" and extreme cool regions on the classification diagrams. In addition, the three late-phase near-infrared (NIR) spectra display the Ca II NIR triplet, Fe II, and Co II absorptions, but no obvious $H$-band break. Although SN 2023vjh falls in the same regions of the classification diagrams as other well-studied 91bg-like events, it shows some deviation within this class. In particular, it is systematically fainter than predicted by explosion models and fainter than other well-studied 91bg-like SNe. Light-curve fitting and color-based analyses indicate a relatively large reddening ($E(B-V)_{host}\sim$ 0.2 - 0.35 mag), which is unusual for 91bg-like SNe. Yet, the lack of detectable Na I D absorption in its spectra, along with its large projected distance from the center of its passive host galaxy (6.8 kpc), suggests that interstellar extinction along the line of sight is minimal. SN 2023vjh appears to be fainter than typical 91bg-like SNe, and it could be affected by circumstellar material (CSM). Comparisons with explosion models and alternative extinction prescriptions show that including CSM-like extinction improves agreement in the blue bands, but residual discrepancies in the $i$-band may reflect limitations in the model.

Quasi-periodic eruptions (QPEs) are repeating soft X-ray nuclear transients with recurrence times of hours-days and flare duty cycles of $\sim$10-20%. Many aspects of QPEs can be modeled as a stellar-mass orbiter that intersects an accretion disk producing a shocked debris cloud and a flare of radiation. We present three-dimensional Athena++ hydrodynamic simulations of star-disk interactions around a $10^{6}\,M_\odot$ supermassive black hole, including the black hole's tidal potential, the disk's Keplerian rotation, and orbital periods similar to those observed. After each disk encounter, freshly stripped stellar debris exits the Hill sphere to form an extended, asymmetric, roughly triaxial stream. Subsequent stream-disk collisions shock both stellar debris and disk gas to high specific energies and drive a wind-like outflow. At larger orbital periods the shocked stellar debris dominates the high specific energy debris, while at shorter orbital periods the shocked disk energy can be similar. From the shocked stellar mass measured in the simulations over time, we infer flare durations set by the time it takes the stellar debris stream to collide with the disk, consistent with the observed constant duty cycle of $\sim$10-20%, independent of orbital period. The total shocked debris energy is consistent with QPE flare energetics. Our results favor one observable flare per stellar orbit except perhaps at the shortest orbital periods where the shocked star and disk energetics can be similar. Variations in the stream's center of mass relative to the star, the stream density, and other properties can produce diverse changes in the time of the flare's peak relative to the time of the star-disk collision. We discuss the implications of our results for QPE timing and for other transients in galactic nuclei.

Cosmic dust is a key regulator of galaxy evolution, but its build-up and survival in the first billion years remain poorly constrained. We present a systematic analysis of dust in the thesan-zoom suite of radiation-hydrodynamical zoom-in simulations, which self-consistently model dust formation, growth, destruction, and its coupling to radiative transfer in galaxies at $z \geq 3$, a multi-phase ISM and bursty star formation histories. The simulated galaxies reproduce the observed trends of dust-to-gas and dust-to-metal ratios with gas metallicity, while showing a dust deficit at high specific star-formation rates. They also broadly match observed dust temperatures and UV-IR spatial offsets. We find that dust and its properties are strongly time-variable and tightly linked to bursty star formation, with short-lived IR-bright phases (median duration of $20.3^{+2.3}_{-2.4}$ Myr) and longer dust-poor phases, naturally producing a correlation between dust temperature and distance from the star-forming main sequence. The predicted attenuation at $1500$ Å is low compared to observations, even when including unresolved dust through post processing, indicating that a mechanism able to shield dust from strong feedback events is necessary to reconcile our galaxy formation model with observations. In our model, bursty star formation prevents the survival of large dust reservoirs ($M_{dust} / M_{star} \geq 10^{-3}$) over a significant fraction of cosmic time. This implies that bursty star formation can produce the observed overabundance of UV-bright galaxies at $z \geq 10$ only if it rapidly settles down by $z \sim 8$ (where large dust reservoirs are detected). It is also possible that our models lack physical ingredients or emergent phenomena that aid the survival of dust. Future observations of high-redshift dust will be key to diagnose the physical mechanism at play in the first galaxies.

Orbits of Milky Way (MW) and M31 satellites in cosmological simulations have been shown to match analytic orbits computed in fine-tuned models of the extended potential of the MW/M31 halos. Using a sample of Local Group (LG) analogs from the Illustris TNG100 simulations, we investigate whether the same is true for LG satellites near the periphery of the LG turnaround radius ($\sim 1\,{\rm Mpc}$), but outside the virial radii of the MW and M31. From both dark matter-only (TNG100-Dark) and full hydrodynamical (TNG100-1) simulations, we track the orbits of dwarf galaxy analogs and compare them with orbits resulting from an analytic model of the LG potential, which is dominated by the dark matter halos of the MW and M31, along with, where appropriate, their most massive satellites. We find that the reconstructed orbits of the selected outer LG satellites agree with the simulated orbits to within $\lesssim 10\%$ over the last 6 Gyr, with the scatter increasing with lookback time and reaching $\sim 40\%$ by 6 Gyr. The fact that orbits of outer LG dwarfs track the analytical models suggests that any excess mass in the outer regions of our LG analogs or the tidal field surrounding the LG does not affect the orbits of outer LG satellites. Residual differences between the analytic and simulated orbits are likely due to a combination of mass accretion for the satellites and MW/M31, the non-spherical nature of the MW/M31 potential, and the prescription for dynamical friction in the analytical models.

We study the hydrodynamical response of a massive black hole accretion disc punctured by a lower mass black hole on an inclined, eccentric orbit, as motivated by the quasi-periodic outbursts seen in the blazar OJ 287. Using three-dimensional smoothed particle hydrodynamics simulations, we explore how the secondary black hole's mass and orbital eccentricity, and the disc thickness and viscosity, affect the time variation of mass accretion onto both black holes. We find that disc-crossing events only lead to significant spikes in the primary black hole's accretion rate when the perturber is quite massive ($q \gtrsim 0.1$) and that such spikes are delayed by roughly a free-fall time ($\sim$ months for OJ 287) after the first disc-crossing. The orbital eccentricity, disc thickness, and viscosity can influence the amplitude and temporal structure of the response; in particular, higher eccentricity causes larger and less delayed delivery of gas to the primary, however the condition $q \gtrsim 0.1$ seems to be robust. We also show that when the secondary is this massive, it generally acquires a "pickup" disc which could produce its own luminous signature. For systems like OJ 287, the secondary pickup disc can contain $10^{2-3} M_\odot$, which if accreted over a timescale comparable to the orbital period can power near-Eddington secondary luminosities with thermal emission peaking in the UV/EUV.

We present the first homogeneous study of the radial distribution of the binary fraction across the full extent of six Galactic globular clusters (GCs) spanning a wide range of dynamical ages, from dynamically young systems to core-collapsed clusters. We measured the radial variation of the binary fraction using a combination of deep optical HST observations and wide-field ground-based data. For the first time, we provide evidence that the binary fraction in GCs does not decrease monotonically with radius, as commonly assumed, but instead exhibits a bimodal distribution characterized by an excess in the outer regions. Specifically, the binary fraction displays a central peak, followed by a minimum at intermediate radii and a rising branch beyond approximately 1-2 half-light radii. The position of this minimum correlates with the cluster relaxation timescale, indicating that it is shaped by long-term dynamical effects of two-body relaxation driving the binary evolution, segregation, and disruption. The minimum radius also correlates with the A+ parameter derived from the radial distribution of blue straggler stars, an empirical indicator of the cluster dynamical age, further supporting the interpretation that this feature is due to internal dynamical processes. Numerical simulations presented in a companion paper show that such bimodal distributions naturally arise from the combined effects of binary disruption and mass segregation of the surviving binaries in clusters.

Collisionless shocks in the intracluster and intergalactic medium (ICM/IGM) are expected to energize both electrons and ions. While electron acceleration is revealed by prominent radio emission, $\gamma$-ray emission from hadronic interactions remains undetected, suggesting that high-$\beta$ (ratio of thermal to magnetic pressure), low-Mach-number shocks cannot accelerate protons efficiently. We present three-dimensional hybrid simulations, in which ions are treated kinetically and electrons as a fluid, of quasi-perpendicular (magnetic obliquity $\vartheta = 80^\circ$) shocks with sonic Mach numbers $M_s \sim 3{-}15$ and plasma $\beta \gtrsim 15$, representative of cluster environments. We find that weak shocks ($M_s \lesssim 5$) fail to develop significant nonthermal populations, with cosmic ray (CR) acceleration efficiencies $\varepsilon_{\rm CR} \lesssim 0.1\%$. In contrast, stronger shocks ($M_s \gtrsim 10$) develop clear power-law tails with slopes $q \sim 4.0 $ and reach $\varepsilon_{\rm CR} \sim 3\%$. These results suggest that weak, oblique ICM shocks are generally unlikely to accelerate protons efficiently. However, reducing $\vartheta$ to $\sim 45^\circ$ leads to substantially higher acceleration efficiencies, indicating that magnetic obliquity plays a critical role in determining proton acceleration. Our findings provide a microphysical framework for interpreting radio relic observations, whose polarization suggests that electrons are accelerated at oblique shocks, and the absence of cluster $\gamma$-ray detections.

The distinct dynamical environments occupied by multiple stellar populations in globular clusters play a significant role in many aspects of cluster evolution, including the dynamics of binary stars. Recent observational analyses of Galactic globular clusters have revealed a bimodal radial trend in the binary fraction: the fraction of binaries is enhanced in both the central and outer regions of clusters, with a noticeable minimum in the cluster's intermediate regions. In this paper, we investigate the dynamical origin of this feature and the mechanisms responsible for preserving this bimodality for an extended portion of a cluster's lifetime. We utilize a suite of Monte Carlo simulations that follow the long-term dynamical evolution of both single-population and multiple-population globular clusters. We investigate how mass segregation and binary disruption function cohesively to produce a bimodal profile, and show that although single-population clusters can briefly generate a similar profile, the effect is weak and transient. Conversely, we show that the structural properties associated with the presence of multiple stellar populations significantly strengthen and preserve the bimodality. We also show that the effects of long-term dynamical evolution drive a broad relationship between a cluster's dynamical age and the radial location of the binary fraction minimum, which tends to migrate outward over time. Overall, our results strongly indicate that the typical multi-scale structure of multiple-population globular clusters (initially characterized by a dense and centrally concentrated subsystem of second-population stars embedded in a more extended first-population system) plays a key role in the origin of the observed bimodal profiles and they further demonstrate the analytical power of binary stars as dynamical tracers of globular cluster formation and dynamical evolution.

Star formation is a fundamental driver of galaxy evolution, yet many galaxy formation models still fail to regulate it realistically, allowing gas to collapse too efficiently and overproduce stars. To investigate a possible solution to this overcooling problem, we perform cosmological zoom-in radiation-hydrodynamics simulations of a dark matter halo reaching $10^{10} M_\odot$ at $z=6$, adopting two distinct star formation models: a Schmidt-type model, in which star formation criteria and efficiency per free-fall time are tied to local gravo-thermo-turbulent conditions, and a sink-based model, in which star formation is governed by local gas inflows. The sink-based model naturally produces bursty star formation through rapid accretion onto young sink particles embedded in strongly convergent gas flows. The resulting intense radiation ionizes and disperses star-forming clumps through photoionization heating before the first supernova explodes. Consequently, supernovae occur in lower-density environments, imparting greater terminal momentum and driving stronger galactic outflows. In contrast, star formation within individual gas clumps is less efficient in the Schmidt-type model, because individual star formation events locally modify cell conditions, temporarily suppressing subsequent star formation and lowering the degree of burstiness. Relative to the Schmidt-type model, the sink-based model yields a total stellar mass lower by a factor of $\sim3$ and a Lyman continuum escape fraction higher by a factor of $\sim10$ by $z=6$. The bursty model drives stronger metal-enriched outflows and suppresses excess central star formation, exhibiting better agreement with JWST observations in gas-phase metallicity and galaxy size. Our results suggest that bursty star formation is a key mechanism for enhancing feedback and alleviating the overcooling problem in galaxy formation simulations.

We present the pulsar search component of SPOTLIGHT (Survey for sPoradic radiO bursTs via a commensaL multI-beam Gpu-powered Hpc at the gmrT), a GPU-accelerated commensal backend operating at the upgraded Giant Metrewave Radio Telescope (uGMRT). While SPOTLIGHT is primarily designed for real-time detection and localisation of fast radio bursts (FRBs), it simultaneously records a subset of beamformed data products for periodicity searches without requiring dedicated telescope time. To process the large data volumes generated by the survey, we have developed a scalable FFT-based pulsar search pipeline that combines radio-frequency interference mitigation, GPU-accelerated dedispersion and periodicity searches, multi-beam candidate sifting, efficient folding and machine-learning classification. Using population synthesis and archival uGMRT observations, we estimate that a fully operational SPOTLIGHT survey with 160 PC and one IA beam could discover $\sim$ 450 new pulsars, probing both high-sky coverage and faint pulsars over three and a half years of commensal observations. The pipeline has been validated on GMRT Cycle 48 and 49 observations (i.e. April 2025 to Mar 2026), successfully re-detecting numerous known pulsars with a wide range of Period, DM and flux densities, and is currently operational for SPOTLIGHT commensal data processing. We describe the SPOTLIGHT observing system, pulsar survey design, search parameter space, candidate-selection strategy, current status, and future developments. SPOTLIGHT demonstrates the scientific potential of commensal pulsar surveys and serves as a pathfinder for real-time, large-scale pulsar and transient searches in the SKA era.

A Gaussian-process classifier on Gaia DR3 XP spectra produced $\sim$30{,}000 white-dwarf main-sequence (WD--MS) binary candidates, each with a probability but no likelihood or goodness-of-fit. The corrected XP BP band keeps a local blue-flux residual of about 2\%, where a hot white dwarf also adds flux. We asked whether that residual contaminates the selection at its realistic amplitude. It does not. The answer turns on one unit: 2\% of total flux, deposited in the narrow blue band, is a median 55\% local excess on a red MS star, 27 times the same number read locally. Injected as a 2\% local excess it gives a spurious rate of 0.08 on a 0.05 baseline through the $\Delta\chi^2$ threshold standing in for the classifier, and an amortized posterior keeps 0.84 of its 90\% coverage against a clean 0.88. The selection fails only above a 10--20\% local excess and reaches 0.96 near 50\%, the raw uncorrected bias that correction and the $B<18$ cut remove. A model-comparison gate certifies binarity only above a WD flux share near 0.05; at the catalog's median share the statistics invert and the spurious carry the larger $\Delta\chi^2$ improvement. The clean reliability signal is off-cooling-sequence UV deficiency (GALEX FUV detection 0.19 against 0.50), robust to a distance control. At the residual the correction leaves, the contamination hypothesis is a null; the open regime is the faint half, where that residual is unmeasured. The audit gives the amplitude it would take, and the shape of the failure past it.

We have analyzed archival FUV and optical spectra of the hot halo star HD 177566. The star has an effective temperature $T_{\rm eff} = 33{,}000 \pm 1000$ K, surface gravity $\log g = 3.79 \pm 0.11$, and helium abundance $\log N({\rm He})/N({\rm H}) = -0.86 \pm 0.05$. Abundances of 13 additional elements are consistent with those of other halo stars, save for carbon, which is underabundant by about 1 dex. The low-order hydrogen Balmer lines are not well reproduced by our models. The diffuse lines of He I are often broader than predicted, but the use of more recent line-broadening parameters significantly improves the fit. Scaling our best-fit model to the star's optical and near-IR magnitudes yields an extinction $E(B-V) = 0.095 \pm 0.005$, consistent with literature values, but the resulting model underpredicts the star's FUV flux by a factor of two. The star's effective temperature and luminosity ($\log L / L_{\odot} = 3.50 \pm 0.08$) place it on the post-AGB evolutionary tracks of a star that evolved from the red horizontal branch. Its low carbon abundance, $\log N({\rm C})/N({\rm O}) = -2.18 \pm 0.21$, indicates that it did not experience significant third dredge-up while ascending the AGB.

With the increased demand for spectrum usage in recent years, particularly with the expansion of NGSO satellite systems for broadband internet and cellular services, radio astronomy observatories located at remote sites have been faced with the challenge of increasingly detrimental RFI exposure from ubiquitous satellite downlinks. With the help of the U.S. NSF, NRAO and the radio astronomy community have spearheaded collaboration efforts with the commercial NGSO operators to develop different coordination techniques to alleviate the impacts of these downlink signals in radio astronomy scientific observations. This paper summarizes the ongoing coordination efforts, spectrum interference avoidance schemes, and a case study on community participation of the Operational Data Sharing (ODS) system between RAS and NGSO operators. We highlight some of the essential lessons learned from these collaborations and potential application of the ODS system to other potential spectrum stakeholders.

The high-mass X-ray binary 4U 1700-377 shows strong variation in brightness on timescales of hundreds of seconds due to accretion from a highly clumped stellar wind from the companion. Using two focused observations and five stray light observations from NuSTAR, we are able to expand the baseline of observations of the source and track spectral parameters throughout the source's variability. The focused NuSTAR observations confidently detect excess emission lines at energies above Fe K$\alpha$, but are unable to universally constrain the nature of these lines independently of model choice. Strong Fe K$\alpha$ fluorescence is ubiquitous in the stray light data, but these observations lack sufficient signal-to-noise to further measure additional emission lines. We discuss the statistics of a claimed cyclotron resonant scattering feature as seen in the stray light spectra, but find no conclusive evidence for its existence. Finally, we investigate two instances of sustained low-flux states of up to 60 ks. When this occurs, luminosity can fall by almost an order of magnitude and the high-energy continuum softens significantly without corresponding to increased absorption. We discuss the manner in which the changing shape of the continuum during these intervals may show accretion during an extended rarefied interval of stellar wind, or a possible change of the dominant accretion regime.

Calibration uncertainties are the leading systematics in cosmological analyses using Type Ia supernovae (SNe Ia). For the \textit{Nancy Grace Roman Space Telescope (Roman)}, we quantify the impact of chromatic effects on SNe Ia photometry and derived cosmological parameters, using simulated light curves from the High-Latitude Time Domain Survey. We investigate two sources of wavelength-dependent bias: focal plane array (FPA)-dependent wavelength shifts arising from spatial variations across \textit{Roman's} 18 detectors, and coherent wavelength shifts corresponding to the measured $0.06\%$ uncertainty in absolute filter wavelength calibration. Using simulated SNe Ia light curves, we find that the FPA-dependent shifts -- which range from +6 to -80 $\rm Å$ introduce a redshift-dependent distance modulus bias that, if left uncorrected, propagates to $\Delta w_0 \sim -0.06$ and $\Delta w_a = -0.236$, which are larger than the forecast statistical uncertainties of $\sigma_{\rm stat, w_0} = 0.025$ and $\sigma_{\rm stat, w_a} = 0.114$, rendering the survey systematics-limited. We probe the impact of chromatic effects by employing detector-specific filter curves that recover unbiased cosmological constraints; to remain below the statistical noise floor, FPA wavelength shifts must be characterized to within 20\%. In contrast, a coherent 0.06\% offset in filter wavelength calibration -- ranging from -3 to -11 $\rm Å$ -- produces negligible redshift-dependent bias, with a minimal spread in $w_a$ ($\Delta w_a = -0.0004, \sigma_{w_{a,\rm sys}} = 0.114)$, demonstrating that the achieved pre-launch calibration precision is sufficient for this systematic to remain subdominant. Our results establish that chromatic effects are a required component of SN Ia cosmology with \textit{Roman}.

Observing auroral radio emission is one of the most promising methods for detecting exoplanetary magnetic fields, which provide valuable insights into planetary interiors, atmospheric properties, and potential habitability. The first hints of exoplanet auroral emission are starting to emerge. Recently, Zhang et al. (2025) reported a detection at 50 MHz of a circularly polarized bursty emission from the HD 189733 exoplanetary system using NenuFAR low-frequency imaging observations. The source of the emission is still unknown and may be caused by planetary auroral emissions, star-planet interactions, stellar activity, or the M-dwarf stellar companion. In this study, we analyze beamformed observations from NenuFAR of HD 189733 taken simultaneously during the previously detected burst. This dataset allows for an independent verification of the detected burst with a different backend and processing steps. Using the BOREALIS data reduction pipeline, we tentatively detect circularly polarized bursty emission ($\sim$10$\sigma$) from HD 189733 $\sim$1 hour before the burst found from the imaging observations. However, some uncertainty remains on whether our detected signal is astrophysical in nature due to excess correlated noise. Assuming an astrophysical origin, our observed characteristics are most consistent with a planetary origin, but stellar emission cannot be completely ruled. Therefore, more low-frequency radio observations are needed to confirm the astrophysical nature of our signal and to search for periodicity in the radio signal from HD 189733 to determine the true cause of the emission. These observations are ongoing. Our study highlights the power of simultaneous beamformed and imaging observations in the search for radio emission from exoplanets.

Ultraviolet (UV) observations provide a powerful window into the hot and evolved stellar populations that shape the structure, evolution and integrated light of star clusters. Because UV wavelengths are highly sensitive to massive main-sequence stars, blue straggler stars (BSS), extreme-horizontal branch (HB) stars, post-HB stars, interacting binaries and compact remnants, they probe key evolutionary processes that are inaccessible at optical and infrared wavelengths. This review synthesises five decades of UV studies of star clusters across the Milky Way, the Magellanic Clouds (MCs) and nearby galaxies, drawing on results from early space missions, wide-field surveys, and high-resolution imaging. In Galactic open clusters, UV studies have revealed compact companions$-$including white dwarfs, hot subdwarfs and stripped stars$-$and have established the mass-transfer origins of BSS, Blue Lurkers and yellow stragglers. In globular clusters, UV imaging has identified multiple stellar populations through UV-sensitive molecular bands, probed helium enrichment and mapped HB morphologies. Wide-field UVIT surveys have extended HST studies with homogeneous catalogues of HB and post-HB stars across entire clusters. In the MCs, UV observations have transformed our understanding of multiple populations, rotation-driven extended main-sequence turn-offs and the UV-dim phenomenon, while spectroscopic surveys have constrained massive-star evolution, stellar winds and binarity at low metallicity. UV mapping of the Magellanic Bridge has revealed ongoing massive-star formation in low-density tidal environments. Beyond the Local Group, UV studies of extragalactic clusters constrain star-formation histories, stellar feedback and population synthesis across galactic environments. Collectively, UV observations now form a cornerstone of star cluster astrophysics and will continue to do so with upcoming missions.

Numerical modeling of solar plasma dynamics is affected by the resolution of the computational grid. This often requires the estimation of subgrid processes related to the small-scale flow turbulence, as these processes play a critical role in momentum transport and energy dissipation. In this work, we investigate the use of deep learning techniques as surrogate models for subgrid turbulent transport in realistic hydrodynamic simulations of the quiet Sun. We describe the development of a 3D Convolutional Neural Network (CNN) to capture spatial dependencies in 3D velocity fields, leveraging different activation functions, as well as different architectural designs. We specifically focus on the prediction of Reynolds stress tensor components. The resultant model integrates velocity vector components and scalar features, such as plasma density, to enhance prediction accuracy. We compare the 3DCNN model to other types of models, such as a Multilayer Perceptron (MLP) and physics-based Gradient and Smagorinsky models, and show that the final model design reconstructs the Reynolds stress tensor components more accurately. Specifically, a 3DCNN model achieves an average improvement of ~31% on diagonal components and ~8% on the off-diagonal components of the stress tensor. Additionally, we show that applying a logarithmic data transformation of the target stress tensor components, to handle heavily skewed data, improves model performance. Results demonstrate the potential of deep learning, particularly CNNs, to approximate Reynolds stress tensor components for the upper solar convection zone and lower atmosphere, making them a viable candidate for modeling subgrid processes and a promising alternative to traditional turbulence models.

We present IRAM--30m observations aimed at identifying potential outflow-interstellar medium interaction sites in the vicinity of the black hole X-ray binary Cygnus X--1, which displays persistent relativistic jets and a prominent stellar wind. Using this dataset, we construct molecular line emission maps, identifying a never before seen molecular structure potentially linked to X-ray binary-driven feedback. This structure, surrounding the source, exhibits properties consistent with an interaction powered primarily by the stellar wind of the massive stellar companion and further sculpted by the relativistic jets. Our results indicate that multiple outflow mechanisms (stellar winds and relativistic jets) may simultaneously be shaping the interstellar medium around Cygnus X--1, and that molecular line imaging can help to disentangle complex feedback processes in environments where multiple outflows take place.

Heliospheric density variations impart delays on pulse times of arrivals from millisecond pulsars. Improper modelling of these variations may affect gravitational wave detection and characterisation by pulsar timing arrays (PTAs). Currently, PTAs typically employ a time-varying, spherically symmetric heliosphere model, which does not capture the full spatial and temporal complexity of the heliosphere. Instead, we investigate whether a three-dimensional, time-dependent model of the inner heliosphere from interplanetary scintillation (IPS) measurements - the IPS-UCSD model - can be employed to mitigate the solar wind in PTA analyses. We applied the IPS-UCSD model to the MeerKAT PTA 4.5-year dataset to assess whether it could correct for heliospheric density variations, and the impact on GW sensitivity compared to a spherically-symmetric model. We find that the model does not accurately correct for heliosphere-induced timing distortions, leading to bias in recovered GW parameters. Using simulations, we show that the spherically symmetric heliosphere model also fails to fully capture heliospheric density variations like those in the IPS-UCSD model. However, if interstellar dispersion measure (DM) variations are also modelled, then the heliospheric model errors are partially absorbed by DM variations, reducing contamination of the GW signal. Therefore we find that a time-varying spherically symmetric model is sufficient to mitigate the effect of heliospheric time delays on recovered GW results at typical PTA radio frequencies, provided other signal components are also modelled. We propose that the most precisely timed pulsars may be used to improve data-driven heliospheric density models in the future.

We report the discovery and multiwavelength follow-up observations of a giant (factor >100) X-ray outburst of the exceptional changing-look active galactic nucleus (AGN) IC 3599. This is the third such outburst after two previous ones serendipitously discovered in 1990 and 2010. Based on our dedicated long-term monitoring of IC 3599 with {\it Swift}, the third outburst was detected while it was happening, and we triggered multiple follow-up observations within days to weeks for the first time. The Swift outburst spectra are supersoft and almost no photons are detected beyond 2.5 keV. The XMM-Newton short-term light curve shows a remarkable apparent oscillatory pattern that is reminiscent of quasiperiodic oscillations (QPOs). The optical high-state spectra reveal a multitude of bright coronal emission lines that have dramatically brightened and were absent or much fainter in low-state spectra. The new results eliminate outburst scenarios that require a constant time interval of repetitions (like certain variants of repeat tidal stripping, or of an orbiting supermassive black hole impacting the inner accretion disk), but remain in excellent agreement with an accretion disk radiation-pressure instability when assuming that local conditions in the disk of this long-lived AGN affect the onset time of each new instability. The combination of recurrent, giant, supersoft outbursts on decadal timescales, the exceptional emission-line response, and the rapid, candidate quasiperiodic, short-term variability on an hours timescale makes IC 3599 unique among AGN, and establishes it as a key system for studying accretion physics under extreme conditions and at the Eddington limit.

The maximum mass of neutron stars provides a key constraint on the equation of state (EoS) of dense matter. Recent observations, including the ${\approx}2 M_{\odot}$ pulsar PSR~J0740+6620, have placed strong constraints on a large class of soft EoSs, while the possible existence of a compact object with a mass of $2.50$ - $2.67$ $M_{\odot}$ in GW 190814 further challenges our understanding of dense matter. Moreover, the inclusion of hyperonic degrees of freedom generally softens the EoS, making it difficult to support massive neutron stars even when the $2$ $M_{\odot}$ constraint is satisfied (a problem known as the hyperon puzzle). In this work, we investigate whether differential rotation can enhance the maximum mass of neutron stars constructed with an EoS including hyperons, thereby addressing the maximum-mass constraints imposed by current observations. We employ the Cook-Shapiro-Teukolsky (CST) approach, a numerically improved reformulation of the Komatsu-Eriguchi-Hachisu (KEH) scheme, to construct equilibrium configurations of differentially rotating neutron stars. For the nuclear matter EoS, we adopt a relativistic mean-field (RMF) model incorporating hyperonic degrees of freedom through an SU(6) symmetric coupling scheme. We find that differential rotation can substantially increase the maximum mass, yielding configurations consistent with the mass range inferred from GW 190814. However, a sufficiently soft EoS fails to satisfy the constraint from PSR~J0740+6620 (346 Hz) even with differential rotation applied. We also present a systematic analysis of the internal structure of the resulting equilibrium configurations. Furthermore, we demonstrate the existence of quasi-toroidal configurations and present equilibrium sequences incorporating the full baryon octet under extreme differential rotation.

The progenitor channels of fast radio bursts (FRBs) remain debated, with a central question being whether their cosmic rate traces star formation promptly or instead follows it with the long time-delay characteristic of compact-binary mergers. We perform a forward-modeling, hierarchical Bayesian analysis of the CHIME/FRB population, jointly fitting the catalog sample, baseband fluences, and localized host redshifts, while self-consistently incorporating the survey selection function through the injection framework. Across a range of delay-time models, the reconstructed FRB rate robustly peaks at the same redshift as the cosmic star-formation history, with a mean delay of only $0.1-0.3$ Gyr that remains consistent with a prompt, zero-delay origin at the $2\sigma$ level. For dominant FRB population, this finding rules out the multi-Gyr delays reported previously and interpreted as the evidence for compact binary merger origin, and instead points toward progenitor systems linked to young stellar remnants, most notably magnetars formed in core-collapse supernovae.

The enhanced X-ray Timing and Polarimetry (eXTP) mission will combine spectral, timing, and polarimetric techniques to study accreting black holes, measure their masses and spins, and test Einstein's theory of General Relativity in the strong-field regime. In this contribution, I review the capabilities of eXTP to advance our current understanding of black hole physics and astrophysics.

The two-point correlation function completely describes a Gaussian random field, but nonlinear gravitational growth, halo bias, and redshift-space distortions drive the late-time halo field strongly non-Gaussian, moving a substantial part of the cosmological information into higher-order correlations. We quantify the information content of the configuration-space two-, three-, and connected four-point correlation functions of Quijote dark-matter haloes at $z=0$ and fixed number density. We build Fisher forecasts for $\{\Omega_m, \Omega_b, h, n_s, \sigma_8, M_\nu\}$ in real and redshift space from ${\sim}38{,}000$ GPU-accelerated $N$-point measurements. Treating the statistics as a ladder, $\mathrm{2PCF} \rightarrow +\mathrm{3PCF} \rightarrow +\zeta^{(4)}_{\mathrm{conn}}$, we report the information gained at each rung. The 3PCF supplies most of the accessible higher-order information: it tightens every parameter, most strongly $\sigma_8$ and $M_\nu$, whose degeneracy it partially breaks, with per-parameter gains consistent with those of the Fourier-space halo bispectrum on the same simulations. The connected 4PCF adds a further $\sim1.4$--$1.5\times$. This rung-to-rung increment is stable against derivative-sample noise and compression regularization, whereas the absolute constraints remain limited by the finite simulation ensembles and are reported as preliminary. We validate the measured 3PCF against a tree-level perturbation-theory model, recovering a linear bias consistent with the 2PCF. The configuration-space ladder thus offers an independent and complementary route to the higher-order information probed by the Fourier-space poly-spectra.

Neutron stars, due to their extremely high matter density and strong magnetic field, provide the best environment for exploring new physics beyond the Standard Model of particle physics. In this work, we study the effect of pre-existing dark matter component and an internal magnetic field on the structural properties of neutron stars. We employed relativistic mean field theory based equations of state and used a single fluid approach for solving the Tolman-Oppenheimer-Volkoff (TOV) equation to compute properties like mass-radius, tidal deformability, compactness, and non-radial oscillation frequencies. We consider the following two scenarios for equation of state (EoS): (1) density-independent couplings along with non-linear interactions of mesons, and (2) density-dependent couplings, with only considering linear interactions for mesons. These mesons mediate the interactions between nucleonic constituents of a neutron star. In the dark matter sector we consider a massive fermionic dark matter which interacts with the nucleons through a Higgs portal interaction. We explore parameter regions for Fermi momentum of dark matter in the range $k_F = 0.01$ GeV - $0.06$ GeV, and two different values of the mass of fermionic dark matter, $M_\chi = 200$ GeV and $300$ GeV. We consider two values of the central magnetic field, $B_c = 7\times10^{17}$ Gauss, $9 \times 10^{17}$ Gauss, for a magnetized neutron star. Finally, we compare the theoretical predictions with the observed mass-radius and tidal deformability data of pulsars obtained from gravitational wave observations.

Astronomical CCD images are often affected by bleeding from bright sources, producing column-aligned streaks that degrade source detection and photometry. We present a pixel-level masking algorithm for bleeding in Korea Microlensing Telescope Network (KMTNet) images, in which these streaks extend along detector columns away from the readout register. The algorithm identifies bleed-generating pixels using a conservative bleeding threshold and a bleeding index that quantifies excess signal along the expected bleeding direction. The extent of each bleed trail is then determined by termination criteria based on a background-relative detection threshold and a continuity condition. To optimize these termination parameters, we generate multiple candidate masks and evaluate them with an F-beta-like score that favors high purity while preserving recovery of sources whose photometry is biased by bleeding. Using the final mask, we apply interpolation-based cleaning and assess the performance in terms of completeness and photometric accuracy in a crowded KMTNet field, using Gaia DR3 as a reference. The source completeness improves from 94.08% to 98.61%, primarily by enabling proper aperture placement that was previously hindered by bleeding. For selected bleeding-affected sources, the root-mean-square photometric offset decreases from 0.623 mag to 0.068 mag. These results demonstrate that the algorithm provides a practical framework for mitigating bleeding artifacts in KMTNet images. We further examine the stability of the algorithm across different observing conditions and discuss limitations of the current masking and cleaning procedure.

Context. The dependence of Type Ia supernova (SNe Ia) standardized luminosity on host galaxy properties constitutes a significant systematic error in cosmology. However, the widely used empirical mass step, acting as an indirect global proxy, obscures the direct physical link to the progenitor environment, thereby limiting the precision of SNe Ia luminosity standardization. Aims. We investigate the fundamental origin of these dependencies by comparing local luminosity-weighted age (LWA) with global mass, testing whether the mass step is a proxy for progenitor age. Methods. Using SDSS-MaNGA Pipe3D, we measure local LWA within a 1 kpc aperture for 56 SNe Ia and perform a joint likelihood analysis to separate the effects of local age and mass on Hubble residuals. Results. SNe Ia in younger environments are significantly fainter than those in older environments, showing an age step of 0.163 mag (5.2-sigma) after standardization. Although global and local mass steps are initially detected (0.071 mag, 2.0-sigma and 0.087 mag, 2.4-sigma, respectively), both become insignificant after accounting for age. The global mass step decreases to 0.028 mag (0.9-sigma), while the age step remains 0.156 mag (4.9-sigma). Similarly, the local mass step decreases to 0.012 mag (0.3-sigma), whereas the age step remains 0.157 mag (4.4-sigma). Including the local LWA age step reduces the Hubble residual dispersion (wRMS) from 0.1550 to 0.1376 mag. Conclusions. Our results provide strong evidence that approximately 50%-60% of the variance from the stellar mass step is due to an environmental dependence on progenitor age. A systematic bias in the dark energy equation of state parameter could be introduced if the age-dependent luminosity evolution is neglected, highlighting the necessity of local age corrections for next-generation cosmology.

Aims. Non-parametric morphological statistics can be used for efficient classification of galaxy mergers. This work aims to compare the performance of morphological merger classifiers to state-of-the-art machine learning (ML) models. A secondary aim is to produce updated criteria for mergers based on non-parametric morphological statistics. Methods. The Gini coefficient (G), $M_{20}$ statistic, and concentration ($C$) were calculated for mock Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) images based on the IllustrisTNG and Horizon-AGN simulations, and observations from HSC-SSP. The IllustrisTNG images were used to find the line which best separates mergers and non-mergers in 2D morphological space with a Markov Chain Monte-Carlo (MCMC) method. Results. Based on the MCMC results, we classified galaxies with $G>(-0.267\pm0.081)M_{20}+(0.143\pm0.012)$ or $G>(0.162\pm0.048)C-(0.149\pm0.12)$ as mergers, these criteria had precisions of 69.5\% and 72.3\% respectively when applied to previously unseen IllustrisTNG mock HSC-SSP images. The precisions of the morphological classifications are consistent with state-of-the-art ML methods. The morphological classifiers were found to be effective at selecting only pre-mergers; post-merger galaxies are indistinguishable from non-mergers in terms of their $G$, $M_{20}$, and $C$ values. Morphological classifiers displayed a similar robustness to new data to ML methods up to a redshift of $\sim0.52$ and maintained robustness better than ML methods based on convolutional neural networks in the redshift range $0.52<z<1$. Conclusions. This work presents updated morphological classifiers which achieve similar precisions to ML based merger classifiers with a high robustness to new data. New morphological statistics are needed to identify the features of post-merger galaxies.

We present updated constraints on both flat and non-flat Dvali-Gabadadze-Porrati (DGP) cosmological models using the latest baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2), in combination with cosmic chronometer (CC), Type Ia supernova (SNIa), and cosmic microwave background (CMB) distance priors. For the non-flat DGP model, we obtain $H_0 = 64.05 \pm 0.27\, \rm{kms^{-1}Mpc^{-1}}$, $\Omega_m = 0.3264 \pm 0.0043$, and $\Omega_k = 0.0088 \pm 0.0016$, corresponding to a transition redshift $z_t \sim 0.41$. For the flat case, the constraints are $H_0 = 63.28 \pm 0.25\, \rm{kms^{-1}Mpc^{-1}}$ and $\Omega_m = 0.3303 \pm 0.0036$. In both scenarios, the inferred Hubble constant is significantly lower than the Planck $\mathrm{\Lambda}$CDM value, indicating that the DGP framework does not alleviate the Hubble tension. Current observations strongly disfavor the DGP framework, primarily due to its inability to simultaneously accommodate DESI BAO and CMB this http URL incorporating the latest high-precision DESI observations within a unified analysis framework, this work provides updated and more stringent limits on the DGP scenario, offering a consolidated assessment of its viability in the context of current cosmological data.

There are indirect signs of the presence of a companion near the star CQ\,Tau. A period of 10\;years was found in the brightness changes. The image of the disk shows an extensive cavity with a size of about 25~AU, surrounded by a dust ring with a distribution maximum near 53~AU. A simulation of the interaction of dust and gas in the vicinity of the star with the CQ\,Tau parameters was carried out, assuming the existence of a companion in an orbit with a period of 10\;years. It was shown that an M-class star in a highly elongated orbit is capable of forming a region of reduced density around the center of mass of the system, with a size close to the observed one. However, the dust ring-like structure in this case is located noticeably closer to the star than observed. Evidence has been obtained that a massive planet in an outer, relatively binary orbit, could form a ring-shaped dust structure at a distance similar to that observed.

We present a new picture of primordial black holes mass evolution through neutrino absorption. Using semi-classical approach and a closer look at the kinetic of the early plasma we revisit the thermal absorption of radiation by a population of primordial black holes ranging from $10^{-3}-10^9 M_\odot$ embedded in a thermal bath. We find significant mass growth of intermediate mass and supermassive PBHs, the effect shift the predicted $e^+e^-$ peak from thermal history. Depending on the value of the collapse fraction an additional peak around the intermediate mass range, might become significant. Moreover, because PBH grow from the thermal bath the fraction of DM in PBH $f_{\rm PBH}$ also change. These results revise the previous view on mass evolution of PBH and have implications for dark matter PBH observations.

The analysis traditionally employed by Imaging Atmospheric Cherenkov Telescopes involves optimizing quality cuts to select a sub-sample of high-quality events. These events are used for the scientific interpretation of the data, employing a single set of Instrument Response Functions (IRFs). All selected events are treated equally and assumed to be well represented by these IRFs, while the rest are discarded. An alternative approach, successfully applied in experiments such as Fermi-LAT, is an event-type-based analysis. This method divides datasets into subsamples, each containing events of a given expected reconstruction quality. IRFs are computed for each subsample independently, improving the accuracy with which IRFs represent the reconstruction quality of each event. The high-level analysis of these subsamples is performed treating them as independent observations, each with their own set of IRFs, and analyzed jointly. In this work we present a proof-of-concept implementation of an event-type-based analysis for the future CTAO using simulated data. A neural network (specifically a multi-layer perceptron) is trained to predict the direction reconstruction error of each event, and the simulated dataset is divided into event types based on this predicted variable. We compute IRFs for each event type and compare them with those from the standard analysis (without event types). Finally, we simulate observations using these event-type-wise IRFs and analyze them with high-level analysis tools to test the performance of both approaches. This implementation demonstrates notable improvements: 25% to 50% boost in spatial resolving power and ~25% in sensitivity. This boost in performance will have strong implications in the scientific exploitation of the CTAO data, especially in crowded regions such as the Galactic Plane or searching for spectral signatures like Dark Matter annihilation lines.

We fit a flexible double power-law (`$\alpha\beta\gamma$') model to the stellar density fields observed for the Milky Way's known dwarf spheroidal satellite galaxies. We show that where standard criteria for model selection are decisive, the $\alpha\beta\gamma$ model is favored over the special case of the Plummer model, and also over the \sersic\ model and its special case, the exponential. The Milky Way's dSph population exhibits a diverse range of stellar density profile shapes, as quantified by the values we infer for outer and inner power-law indices $\beta$ and $\gamma$. Several of the most massive dSphs (e.g., Eridanus II, Fornax, Leo I, Leo II) have steeply-declining outer profiles, with $\beta\gtrsim 8$; others (e.g., Sextans, Boötes I) fade slowly, with $\beta\lesssim 4$. The inner profiles of dSphs with stellar mass $\gtrsim 10^5 M_{\odot}$ are consistent with `cores' of uniform stellar density ($\gamma\approx 0$). At lower masses the slopes of inner density profiles are poorly constrained, except in a few ultrafaint dSphs (e.g., Hercules, Ursa Major II) where we infer steep stellar cusps, with $\gamma\gtrsim 1.5$. Owing to the $\alpha\beta\gamma$ model's flexibility, the inferred halflight radii and total stellar masses are significantly more uncertain than previous estimates, with halflight radii larger by up to an order of magnitude in some cases. Finally, we demonstrate that allowing for flexibility in the shape of the stellar density profile is crucial for dSph mass modeling, where systematic errors associated with choice of stellar density profile can outweigh random errors in the observed velocity dispersions.

Context. The architecture of our Solar System, with inner small planets (ISPs) and outer giants, may or may not be common. Understanding whether a correlation exists between ISPs and outer cold giants is key to evaluating how common systems with a similar architecture to our own are. Aims. This study aims to build a large, homogeneous sample of systems hosting cold Jupiters (CJs, a > 1 au, msini > 0.1 M$_J$) detected via radial velocities (RVs), and to assess the presence of additional ISPs (P < 400 d, 3 < msini < 31.7 M$_{\oplus}$), studying the correlation between these two types of objects. Methods. We selected 137 stars known to host a CJ, including 23 which also harbor a hot Jupiter and were treated separately. Data from various instruments were compiled, including unpublished data gathered with HARPS-N within the GAPS program, and consistently fitted using PyORBIT. We derived RV detection maps and calculated occurrence rates for ISPs, cross-validating results with two independent codes. The sample was divided into subgroups to evaluate how system parameters influence planet occurrence. Results. We confirmed the 213 already known planets in the 137 systems and also identified six new candidates. We divided them, based on mass and period, into Neptunes (10 < m sin i < 31.7 M$_{\oplus}$) and Super-Earths (3 < m sin i < 10 M$_{\oplus}$), and into hot (1 < P < 10 d), warm (10 < P < 100 d), and cool (100 < P < 400 d). We found occurrences of 5%, 13%, and 12% for hot, warm, and cool Neptunes, respectively, and 11% and 16% for hot and warm Super-Earths, respectively. Systems with dynamically stable inner regions show higher rates of small planets. These findings are consistent with previous studies showing no strong correlation between ISPs and CJs at average stellar metallicity and mass, and suggest that HJs may be more commonly associated with external giants.

We aim to derive statistically robust and physically interpretable BE distributions for atomic S and the sulfur-bearing molecules H$_2$S, SO$_2$, and OCS on neutral and negatively charged ASW, and assess how excess negative charge alters their retention and potential role in the sulfur reservoir of cold dense molecular clouds. Basis set superposition error (BSSE) and zero-point energy (ZPE) corrected BEs of S, SO$_2$, OCS and H$_2$S, are calculated by density functional theory (DFT), using the ORCA software. Molecule-specific DFT levels of theory were first selected from benchmark calculations on neutral and charged small water complexes, against coupled-cluster reference energies. The selected protocols were then applied to study adsorption on neutral and charged ASW clusters. A range of adsorption sites were sampled on five independent amorphous ice clusters, yielding BE distributions that account for the site heterogeneity of ASW. Neutral ASW yields broad, site-dependent BE distributions consistent with previous water-ice estimates. On charged ASW, three general cases are identified: the BE will either always increase due to electron transfer (S-atom, SO$_2$), the BE increases slightly without any electron transfer (H$_2$S) or the BE remains the same unless an electron transfer occurs under specific conditions (OCS). These findings are inherently linked to the molecular properties of these molecules.

The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a next-generation wideband radio interferometer currently being constructed and commissioned at the Dominion Radio Astrophysical Observatory in British Columbia, Canada. CHORD is designed for precision 21\,cm cosmology, fast radio transient discovery, spectral line galaxy surveys, and pulsar science using a highly redundant large-N, small-diameter drift-scan array architecture. The telescope consists of a 512-element core array of 6\,m dishes operating from 300--1500\,MHz in drift-scan mode, together with two 64-dish outrigger stations located at the Hat Creek Radio Observatory and the Green Bank Observatory for long-baseline transient localization. The instrument supports multiple simultaneous digital backends for interferometric correlation, FRB detection, pulsar beamforming, and high spectral resolution surveys. CHORD is designed with an emphasis on precision beam control and stable instrumental response, incorporating lessons learned from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) while providing a substantial increase in sensitivity. Initial performance has been evaluated using a three-dish engineering array, and a 64-dish pathfinder array is currently being commissioned. The full array will be commissioned in 2028.

This work presents a novel stick-slip piezoelectric actuator for the FLEX fibre positioner, addressing the challenge of reducing footprint while maintaining precision in next-generation multi-object spectroscopic instruments such as the Wide-field Spectroscopic Telescope (WST). The actuator combines compact geometry (3.2 mm diameter, sub 70 mm length) with high-resolution incremental motion, low power consumption, and high reliability. Three actuators can be integrated into a sub 7 mm diameter circle, enabling a simplified, single-plane assembly. This design offers a promising solution for miniaturized, accurate fibre positioning in wide-field spectroscopic applications.

Constraining ionization and excitation processes in protoplanetary disks is essential for understanding the chemical structure and evolution of disk material, shaping planet formation pathways. We present JWST/NIRSpec IFU observations of the edge-on disk Oph 163131, which reveal a unusual ro-vibrational H$_2$ spectrum dominated by the 1--0 O(2) line (2.627 $\mu$m), with suppressed higher-$J$ emission despite excitation to $v=2$ and $3$. This vibrationally hot, rotationally cold H$_2$ emission is spatially extended, broadly following the molecular disk traced by CO($J{=}2$--1), with emission increasing above and below a thin midplane dark lane and extending radially beyond $\sim$200 au, where near-IR scattered-light emission is no longer dominant. We interpret the observed H$_2$ emission as arising from non-thermal excitation in cold, dense outer-disk gas, where collisions depopulate higher-$J$ rotational levels within each vibrational manifold prior to emission, producing the characteristic ``$v$-hot, $J$-cold" spectrum. We consider both ultraviolet irradiation and cosmic-ray excitation as contributors to the H$_2$ emission and find that their combined action, together with collisional de-excitation of high-$J$ level populations, broadly reproduces the observed line ratios and morphology. Within this framework, we infer a rather high effective cosmic-ray ionization rate of $\sim(1$-$10)\times10^{-15}$ s$^{-1}$ in the presence of a moderate UV field ($\chi_{UV}=100-1000$, in Draine units). These results for disks, together with the recent findings by Bialy et al. 2025 for the lower-density starless core B68, highlight the potential of ro-vibrational H$_2$ emission as a novel probe of cosmic-ray ionization.

We investigate the dynamics of domain walls in scalar field theories with degenerate vacua (i.e., vacua of equal energy density) in which the scalar field mass depends on the vacuum state. Using analytical arguments and numerical simulations, we show that this vacuum dependence of the scalar field mass renders the emission of scalar radiation from domain walls anisotropic, preferentially toward regions with smaller scalar field mass. We further show that the resulting recoil (rocket) effect biases the evolution of cosmological domain wall networks in favor of the lower-mass vacuum, thereby promoting network decay. We also demonstrate that the biased evolution of domain walls in theories with degenerate vacua, previously attributed to asymmetries of the potential barrier near the local maximum, is instead primarily controlled by the vacuum dependence of the scalar field mass. More generally, in theories with non-degenerate vacua, this recoil mechanism constitutes an additional source of dynamical bias that can either hasten or delay network decay relative to the standard expectation based solely on differences in vacuum energy density.

Close-in sub-Saturns (4 - 8.5 R$_\oplus$) are depleted in the Neptunian desert, accumulate in a narrow overdensity near P = 3.2 - 5.7 d (the Neptunian ridge), and thin out into the more moderately populated savanna at longer periods. We test whether sub-Saturns have systematically different companion architectures, as predicted if desert and ridge planets arrived through high-eccentricity migration while savanna planets migrated quiescently. We compile 86 systems with both transit and RV data, construct completeness maps and combine them into detection probability surfaces for companions. The combined completeness maps are used to calculate companion occurrence rates across different companion types with a Poisson-Binomial framework. Companion architectures differ significantly across the landscape. $69.9_{-7.7}^{+6.9}\%$ of savanna sub-Saturns have nearby companions (P < 200 d) compared to only $10.5_{-5.3}^{+7.8}\%$ of desert and ridge sub-Saturns. Additionally, sub-Saturns in the savanna often reside in multi-planet systems with $64.4_{-9.8}^{+8.9}\%$ having more than one companion planet versus only $14.9_{-9.1}^{+13.7}\%$ in the desert and ridge. In both populations, the nearby companions that do exist are almost exclusively small (M < 20 M$_\oplus$), meaning the sub-Saturn is typically the dominant body of its inner system. These contrasts are robust to crosscuts in sub-Saturn radius, bulk density, eccentricity, and host-star properties. Desert and ridge sub-Saturns reside in dynamically emptied systems whose nearby companion rates match those of hot Jupiters, while savanna sub-Saturns inhabit compact multi-planet systems resembling those of warm Jupiters. This parallel supports two migration channels operating within a single population: HEM delivering planets to the desert and ridge, and quiescent disk migration or in-situ formation populating the savanna.

We report on JWST/MIRI imaging and spectroscopy of two M-dwarf stars previously singled out by project Hephaistos as potential Dyson-sphere candidates (their candidates D and E) due to the presence of excess flux at mid-infrared wavelengths. We find that the infrared excess does not originate from Dysonian megastructures, or other radiation mechanisms close to these stars, but from background galaxies projected within $\sim 1$ arcsec of the M dwarfs, thereby confusing previous mid-infrared photometry obtained with the WISE telescope. The candidate D background galaxy lies at redshift $z\approx 0.9$, appears point-source dominated in imaging and has a mid-infrared spectrum consistent with being a Hot Dust Obscured Galaxy (Hot DOG). The candidate E background galaxy lies at $z\approx 0.4$, displays an extended morphology with bright knots and a spectrum consistent with a dusty starburst.

Star-forming regions are key to understanding the formation and early evolution of stars. Young stellar objects (YSOs) form groups with distinct kinematic and spatial properties, inherited from the turbulent dynamics of their parent molecular clouds. The high-precision astrometry and photometry from Gaia Data Release 3 (DR3) enable detailed studies of these groups' three-dimensional motions and their evolutionary stability. This study aims to investigate the kinematic properties and evolutionary consistency of YSO associations in the solar neighbourhood. Here, we show that HDBSCAN clustering of Gaia DR3 data yields 145 YSO groups comprising 5713 stars within 1 kpc, with a derived Larson's relation of $\sigma_v = (1.10 \pm 0.13) \times r^{0.38 \pm 0.03}$, consistent across age bins up to 20 Myr. This slope aligns with the canonical value of 0.38 and typical ranges of 0.4--0.5. The stable Larson's relation across ages indicates that the inherited turbulent structure from parent clouds persists without significant disruption. These findings establish a benchmark for studying the kinematic legacy of star-forming regions.

We investigate the forces acting on a proton vortex in superconducting neutron-star matter composed of neutrons, protons, and electrons, accounting for Fermi-liquid interactions in the neutron-proton subsystem. While the force arising from electron scattering by the vortex magnetic field is well known, we demonstrate that normal neutrons also exert a force on proton vortices due to Fermi-liquid coupling with superconducting protons. Using a kinetic approach based on Landau Fermi-liquid theory, we show that neutron quasiparticles scatter off a proton vortex through the spatially varying condensate momentum, giving rise to a longitudinal force proportional to the relative neutron-vortex velocity. In contrast to the electron contribution, this force has no transverse component and vanishes in the absence of neutron-proton Fermi-liquid interaction. Within a simple model, we analyze the main properties of this force and provide physically motivated estimates of its magnitude.

Astrophysical processes associated with galaxies may contribute to the magnetization of cosmic voids. We investigate the diffusion of galactic magnetic fields in an expanding universe in the presence of turbulent magnetic diffusivity. To estimate the turbulent magnetic diffusivity, we analyze the TNG50-1 data set of the IllustrisTNG simulation and derive its redshift dependence from the characteristic turbulent velocity and turbulent scale of the intergalactic medium. Using the resulting diffusivity, we find a present-day magnetic screening length of $\sim 7\,{\rm Mpc}$, roughly twenty times larger than previous estimates based on a constant turbulent diffusivity due to the larger turbulent scale obtained in our analysis. This scale corresponds to a significant fraction of the characteristic size of cosmic voids and suggests that galactic magnetic fields can play a more important role in void magnetization than previously estimated.

We present recent enhancements to VLTI observing capabilities from a user-oriented perspective, together with new developments in ESO's Observation Handling Tools and end-to-end operations model for VLTI. Key upgrades include GRAVITY+ Coudé guiding with laser guide stars at the UTs, improved limiting magnitudes for GRAVITY and MATISSE, and a new MATISSE narrow-field off-axis mode, all supported by a streamlined, uniform template structure. Phase 2 tools now enable finding-chart generation and the selection of Coudé guide stars and fringe-tracker targets, and will soon offer expanded preparation features and uv-coverage visualisation. We summarise usage statistics for snapshot, astrometric, imaging, and time-series observations, outline VLTI scheduling considerations, and present new video tutorials. Starting in 2026, an archive data stream of reduced GRAVITY dispersed visibilities has become available. Complementary community engagement in VLTI operations continues to grow. We close by identifying operational lessons for future interferometric facilities, including the importance of an end-to-end data-flow and user-support model, flexible scheduling, high-level observation-preparation tools, and coordinated community support to keep complex interferometric facilities usable by a broad community.

Every resolved image of a relativistic jet encodes its magnetic field, yet no image records which way the field points along the axis. Synchrotron intensity and linear polarization are blind to this: both probe the field only through even combinations of its components. We introduce H-MOG, a variational method that reconstructs the 3D field on a lattice from two projected observables, the jet width W(z) and the linear polarization p(z), regularized by a Hamiltonian prior and optimized with automatic differentiation. We apply H-MOG to ten GRMHD simulations spanning MAD and SANE states and five black-hole spins (a* = -0.94, -0.5, 0, +0.5, +0.94), and test three routes to break the intrinsic sign degeneracy of the reconstruction: a Faraday rotation-measure term, full 3D sampling, and a Blandford-Znajek spin prior. The unsigned field orientation is recovered at <|cos|> ~ 0.95-0.98, far above the random expectation of 0.5. The sense of the poloidal field, however, is not recovered, and we prove it cannot be: W and p are invariant under B -> -B. All three routes to break this degeneracy fail for distinct physical reasons; the spin-sense relation in these turbulent jets is not monotonic, differing sharply between MAD and SANE. Recovering the sense requires a parity-odd observable: Faraday tomography or circular polarization.

We present a hybrid halo model, which improves the description of the 2-halo term by incorporating non-linear information from simulations. A linear computation of the halo-halo power spectrum is inaccurate at the transition between the 1-halo and 2-halo regimes, whereas nonlinear approaches such as Hybrid Effective Field Theory (HEFT) are not naturally compatible with the halo model decomposition. We address this limitation by constructing a collapsed HEFT (CHEFT) framework, in which the power-spectrum templates of the HEFT operator expansion are measured from simulations where 1-halo contributions are removed by collapsing particles to their halo centres. The halo-halo power spectrum is then expressed as a sum over bias operators, with mass-dependent bias parameters deduced from simulation using the probabilistic bias approach. This provides a predictive model in which there are no free bias parameters. We validate the model for a range of weighting schemes designed to mimic the halo-mass dependence of astrophysical observables, including the Sunyaev-Zeldovich effect, the Cosmic Infrared Background, and galaxy abundances described via a halo occupation distribution. For the matter field, the model recovers the power spectrum to percent-level accuracy across the transition regime. For weighted tracers, the baseline model achieves accuracies of $\sim 5-10\%$ in power, which improves to the $\sim 3-5\%$ level when including an effective higher-derivative, Laplacian-like contribution in the bias expansion. The CHEFT model thus retains the precision and flexibility of the EFT approach, while allowing the transparent incorporation of astrophysical effects that are directly associated with haloes.

Current observations reveal persistent tensions with the standard cold dark matter paradigm, raising the question of whether these can be explained by baryonic physics alone or require alternative dark matter models. One such alternative is fuzzy (or wave) dark matter, consisting of ultralight particles with mass $m \sim 10^{-22}$ eV and de Broglie wavelengths on kpc to Mpc scales, which may give rise to large--scale interference patterns in non-linear structures around the cosmic web, such as filaments and clusters. In this work, we search for possible signatures of these interference fringes by investigating periodicities in the distribution of galaxies around cosmic web filaments. To demonstrate our methodology, we compare the filament profiles to a simple model that includes a periodic component of the form $A\cos(2\pi d/ \lambda)$, where $A$ is the maximum density contrast (amplitude) of the periodic component, with wavelength $\lambda=\lambda_0 \cos\theta$ for some face-on wavelength $\lambda_0$ inclined at an angle $\theta$ to the line of sight. Exploiting the large Sloan Digital Sky Survey (SDSS) Main Galaxy Sample, we analyse a sample of 4,394 filaments from the Tempel et al. filament catalogue, each containing at least 10 member galaxies. We find a vast portion of the parameter space is consistent with the observations at the $2\sigma$ level, including all models with $A = 0$ (no periodicity). We identify a region of the parameter space in tension with the observations, allowing us to exclude values of $A > 0.16 \lambda_0 + 0.18$ for $0.2\,\text{Mpc}\,\lesssim \lambda_0 \lesssim 2\,\text{Mpc}$ at the $3\sigma$ level, demonstrating the ability to test models of filament dark matter structure using this methodology.

The cube method reduces conjunction screening in orbital debris simulations to $\mathcal{O}(N)$ cost by evaluating only object pairs sharing the same grid cell at each snapshot, but systematically assigns zero collision probability to pairs separated by a cell boundary at that epoch, a failure known as boundary blindness. This paper introduces the Double Cube (DC) method, which recovers boundary-crossing conjunctions through a spatially shifted secondary grid using bin-index lookup alone, preserving $\mathcal{O}(N)$ complexity. Validated across 8,000 Monte Carlo seeds, DC reduces the blindness rate from $\beta_{\mathrm{Cube}} = 9.70\%$ to $\beta_{\mathrm{DC}} = 4.21\%$; a synchronized experiment confirms the residual is temporal in origin by reaching exactly $0.00\%$. Removing blindness reveals a systematic per-pair overestimation in the cube formula that blind zero-probability assignments had been masking, suppressing the overall predicted collision rate below the true rate. Two independent corrections are derived and validated: a power-law correction motivated by the Direct Simulation Monte Carlo kinetic theory analogy reduces the calibration error from $12.9\%$ to $1.9\%$ at $k = 1$ and $4.0\%$ at $k = 2$, bracketing perfect calibration from opposite sides; a parameter-free Gaussian correction derived from the pair-distance distribution geometry achieves a residual of $0.08\%$. Both corrections have been implemented in MOCAT-MC.

Little Red Dots (LRDs) are a population of compact red sources discovered by the James Webb Space Telescope (JWST). Imaging and spectroscopy have shown that LRDs exhibit a complex spectrum with a ``V-shaped" continuum, broad Balmer emission lines, and in some cases Balmer absorption. While the physical origin of these components remains debated, recent studies propose that they arise from a compact central engine likely hosting a rapidly growing black hole embedded within a more extended host galaxy. We test this central engine + host galaxy model using JWST/NIRSpec integral field unit (IFU) spectroscopy to spectrally decompose the observed continuum, narrow and broad emission lines, and absorption. We spatially map each component for five broad Ha-selected LRDs at z~5 observed with both the prism and high-resolution G395H grating. We find that the blue continuum emission is co-spatial with the narrow emission line region, while the red continuum arises from a compact core co-spatial with the broad Balmer emission and absorption. Spatial maps of the [OIII] equivalent width reveal a pronounced decrease in the central core. Our work provides further evidence that the LRD emission is produced by at least two distinct physical components arising from a red central engine embedded within a blue host galaxy.

We report the confirmation and characterisation of two moderate-period sub-Jovian planets transiting the bright F-type star HD 148797 (G=9.4 mag, Teff=6441 +/- 51 K). Using photometric time series from TESS and CHEOPS, we determine orbital periods of 42.1 d for HD 148797 b and 68.2 d for HD 148797 c, putting the period ratio very close to the golden mean at 1.619 and therefore near several strong harmonics, and measure planetary radii of 8.25 +/- 0.37 RE and 8.37 +/- 0.38 RE, respectively. We detect significant anti-correlated transit-timing variations for both planets, which contain enough harmonic information to yield photodynamical masses of 39.3 +13 -8.5 ME for HD 148797 b and 39.6 +/- 9.3 ME for HD 148797 c. The corresponding bulk densities, 0.39 +/- 0.12 and 0.377 +/- 0.084 g/cm3, place both planets among the low-density sub-Jovians of the Neptunian savanna. The architecture of HD 148797 is not unusual within this regime: we find that detected multi-system fractions in the savanna remain at ~70-90%, and that most savanna multi-planet systems contain at least one adjacent planet pair with Pout/Pin < 3. This pattern suggests that savanna sub-Jovians are commonly found in dynamically cold systems, consistent with smoother migration pathways such as disk-driven migration rather than disruptive high-eccentricity tidal migration. As a bright, co-evolved system hosting two warm savanna sub-Jovians with similar radii and masses, HD 148797 is also a promising target for comparative atmospheric characterisation.

Exoplanets are high-value targets for a variety of ground and space-based telescopes. All known exoplanets are Galactic, and a fraction of them orbit compact objects. In this work, we investigate the possibility of detecting extragalactic exoplanets orbiting stellar-mass compact binary coalescences (CBCs), such as binary neutron stars, neutron star-black holes, and binary black holes, using future gravitational wave (GW) detectors, including A+ (LIGO in O5), Einstein Telescope, and DECIGO. We use the technique of reconstructing an external potential's profile by extracting information about the centre-of-mass (CoM) kinematics of a CBC encoded in the GWs it emits. In this work, the external potential is provided by the circum-CBC exoplanet, and the resulting signature on the GW waveform comes from the ``wobble'' of the CBC's CoM around the CBC-exoplanet barycentre. As a proof of principle, we consider a few example CBCs detectable with future detectors and a range of circum-CBC exoplanet parameters in circular and eccentric orbits. We find that for a significant fraction of the range of parameters considered, we can identify the presence of a circum-CBC exoplanet by extracting its mass (up to an unknown orbital inclination angle) within a factor $\mathcal{O}(1)$ of its true value, at $68\%$ confidence.

We introduce the Seesaw Reheating scenario, in which the inflaton transfers its energy to a long-lived intermediate scalar associated with the spontaneous breaking of lepton number before the Universe is reheated through its decay into right-handed neutrinos. As a result, the reheating temperature is no longer determined by the inflaton decay width but by the dynamics of the seesaw sector. We derive analytical solutions describing the complete reheating history, revealing two characteristic features of this scenario: the relativistic time dilation of the intermediate scalar, which suppresses its decay and delays the transfer of energy to the thermal bath, and its subsequent transition from a relativistic to a non-relativistic regime, introducing a new characteristic timescale in the thermal history. Together, these effects lead to simple analytical expressions for the reheating temperature. When the intermediate scalar is identified with the field responsible for the spontaneous breaking of lepton number, the same framework naturally connects the reheating temperature to the origin of neutrino masses and provides a well-motivated setting for sterile-neutrino dark matter.

We propose a novel mechanism for generating correct relic of dark matter (DM) which otherwise gets thermally overproduced from the conventional freeze-out mechanism. The mechanism, dubbed as {\it Dark Phoenix}, relies on a transient decay window for DM after its freeze-out which brings its relic within observed limits. Due to finite-temperature effects on masses, DM $\psi$ becomes heavier than its dark sector partner $\phi$ in this window allowing it to decay. The decay of DM then stops after $\phi$ gets a sudden jump in its mass from a first-order phase transition (FOPT) driven by another scalar $\eta$. The dark sector partner $\phi$, assumed to be a charged scalar, undergoes sufficient pair annihilation during this epoch such that its late decay into DM does not overproduce the latter again. While direct-detection rates of DM remains suppressed due to small couplings, the charged scalar $\phi$ can have interesting signatures like long-lived charged track at colliders. The associated FOPT can also lead to observable gravitational waves at future experiments like LISA.

We study the static response of dense neutron-star matter to a prescribed magnetic-field strength within a deliberately minimal and internally consistent relativistic mean-field (RMF) baseline. The model includes neutrons, protons, electrons, and muons in beta equilibrium and charge neutrality, with a uniform external magnetic field incorporated through Landau quantisation of the charged species. The equation of state is evaluated self-consistently at zero temperature, while moderate finite-temperature effects are estimated through leading-order degenerate Sommerfeld corrections. Magnetic pressure anisotropy is included through the Maxwell contribution in the no-magnetisation approximation. The purpose of this baseline is to isolate the hierarchy of magnetic-field effects before introducing additional microphysics or dynamical magnetic-field evolution. We compare the linear QHD-I parameterisation, used as a stiff benchmark, with the nonlinear GM1 model as a more realistic reference. The results show that canonical magnetar-scale fields produce negligible changes in the bulk core equation of state, while visible Landau-quantisation and pressure-anisotropy effects emerge only as the field approaches the strongly quantising regime. The comparison between QHD-I and GM1 further shows that nuclear-model dependence dominates over static magnetic-field corrections up to the field strengths explored here. As an exploratory diagnostic, we use the isotropised equation of state to estimate the sensitivity of ordinary TOV mass--radius sequences to the prescribed magnetic field. This should not be interpreted as a fully anisotropic magnetised-star calculation. Anomalous magnetic moments, hyperons, quark degrees of freedom, and dynamical magnetic-field evolution are left for future extensions.

It has been argued that degenerate higher-order scalar-tensor theories and the effective field theory (EFT) of dark energy are endowed with the Vainshtein mechanism, resulting in a screened fifth force in the exterior of a gravitational source. However, spherical symmetry has been assumed in most of the discussions so far. In this paper, we study whether the Vainshtein mechanism operates in the EFT of dark energy beyond spherical symmetry, focusing in particular on the role of the ``beyond Horndeski'' EFT parameters. Assuming that deviations from spherical symmetry are small, we compute multipole moments of the gravitational potential for a given nonspherical source. For a generic choice of the ``beyond Horndeski'' EFT parameters, it is shown that the multipole moments of the fifth force are not screened in the region where the monopole component is screened. Rather, the gravitational potential shows a characteristic oscillatory behavior in its multipole components. In the special case where the EFT parameters are tuned so that graviton decay into dark energy is practically absent, the behavior of the multipole moments is qualitatively different from that in the generic case. However, also in this case, the Vainshtein mechanism is not efficient enough to screen the fifth force around the source.

We investigate majoron dark matter in a minimal setup, where the Standard Model is extended by three right-handed neutrinos and a complex scalar field. The theory is defined by an exact discrete gauge symmetry, $Z_N\subset U(1)_{B-L}$, while the global $U(1)_{B-L}$ symmetry emerges only as an accidental symmetry at low energies. For nontrivial choices of the discrete symmetry $Z_N$, such as $Z_5$, $Z_7$, $Z_{11}$, and $Z_{13}$, Planck-suppressed operators explicitly break this accidental symmetry and generate a small majoron mass, making the resulting pseudo-Nambu--Goldstone boson a well-motivated dark matter candidate. We study its production via the misalignment mechanism after inflation, considering both radiation-dominated and early matter-dominated cosmological histories, and confront the viable parameter space with isocurvature bounds, cosmological constraints, and indirect dark matter searches. We find that the $Z_5$ model is excluded by limits on the dominant dark matter decay into neutrinos, whereas the other models remain viable. In particular, the $Z_7$ scenario predicts a majoron mass in the $1$--$10\,{\rm MeV}$ range and can be sensitively probed by future MeV gamma-ray observations, especially with COSI, through the 511$\,$keV line from the majoron decay into an electron--positron pair and the monochromatic gamma-ray line from its decay into two photons.

Microwave kinetic inductance detectors (MKIDs) are generally read out with microwave readout tones of high enough amplitude to adequately suppress the noise contribution of the first-stage amplifier. At high readout power, the detector's resonant frequency is altered as a result of the dependence of the kinetic inductance on the internally circulating microwave current. With the tone placed below the resonant frequency, the nonlinear frequency shift results in a positive feedback effect that can significantly enhance the responsivity of the detector, to both optical and microwave power. We report a factor of 10 enhancement in optical response by tuning the readout power and frequency to close to the resonator's bifurcation point. A corresponding decrease in the bandwidth of the resonator is observed under these conditions. We show that the strength of the feedback effect can be easily selected by adjusting the excitation, and provide a map of possible operational states to do so. Operation of MKIDs in this mode could be used to improve sensitivity when non-intrinsic noise sources are significant.

The p-process is responsible for the production of the stable neutron-deficient nuclei heavier than iron observed in the solar system. However, important nuclear uncertainties still limit our understanding of this nucleosynthesis process. Among the most significant are the nuclear level densities (NLDs) and photon strength functions (PSFs) entering the calculation of photodisintegration rates under supernova conditions. We investigate both model (systematic) and parameter (statistical) uncertainties affecting NLDs and PSFs and quantify their impact on p-process nucleosynthesis in type-Ia and type-II supernovae. Correlated model uncertainties are estimated using several NLD and PSF models that reproduce available experimental observables. Uncorrelated parameter uncertainties are evaluated with a backward-forward Monte Carlo approach, in which parameter variations are constrained by measured reaction rates before being propagated to unknown cross sections of neutron-deficient nuclei. The resulting uncertainties are propagated through p-process calculations while preserving model correlations. To identify the reactions driving abundance uncertainties, we combine regularized linear-response modeling, stability analysis, and contribution and interaction decompositions. We find that photoneutron-emission uncertainties dominate the overall uncertainty budget. The leading source of uncertainty arises from local parameter variations still compatible with current experimental constraints, highlighting the lack of constraining nuclear data in the neutron-deficient region. For many p-nuclei, the dominant contribution originates either from the photoneutron emission of the p-nucleus itself or from a nearby $(\gamma,n)$ reaction along the same isotopic chain. While improved nuclear models remain important, many key reactions involve stable or near-stable nuclei and should be experimentally accessible.

Charged-current (anti)neutrino interactions create $\Lambda$ and $\Sigma$ hyperons \emph{inside} the nucleus, making hyperon final-state interactions a terrestrial probe of the in-medium potentials that govern hyperon onset in neutron stars. In the StrangeMC simulation the trapped-$\Lambda$ fraction, escaping hyperon momenta, and a kaon-vetoed $\Sigma^+$ tag respond monotonically to $U_\Lambda$ and $U_\Sigma$ at SBND and DUNE. Marginalised over the low-density slope, a forecast gives $\delta U_\Lambda\approx6\MeV$ with systematics distinct from hypernuclear data; $U_\Sigma$ is limited by hyperon--nucleon cross sections.

Hyperon single-particle potentials $U_Y(\rho)$ control propagation in nuclei and hyperon onset in dense matter, where they soften the neutron-star equation of state and reduce the maximum mass -- the ``hyperon puzzle''. We show that charged-current accelerator (anti)neutrino interactions on $^{40}$Ar, producing $\Lambda$ and $\Sigma$ inside the nucleus, can constrain these potentials. At SBND and DUNE energies, the trapped-$\Lambda$ fraction and escaping-hyperon momenta vary monotonically with $U_\Lambda$ and $U_\Sigma$, with a kaon-vetoed FSI-$\Sigma^+$ tag adding sensitivity. Inserted in a GM1 relativistic mean-field equation of state at established hypernuclear/$\Sigma$-atom depths, the same potentials give $M_{\rm max} = 1.94\,M_\odot$ and $\Lambda_{1.4}=1034$, below the heaviest pulsars and above the GW170817 bound typical of GM1-class mean fields. A detector-level Fisher forecast yields $\delta U_\Lambda \simeq 0.3\,$MeV and $\delta U_\Sigma \simeq 3$-$4\,$MeV for fixed low-density exponent $\gamma$. Since hyperons are produced below saturation, $U_\Lambda(\rho_0)$ and $\gamma$ are 99.8\% anti-correlated; marginalising over $\gamma$ degrades the anchor to $\delta U_\Lambda \simeq 5.6\,$MeV ($1.3\,$MeV with a $\pm 0.2$ prior), while $\delta U_\Sigma$ is unchanged. For $U_\Lambda$, comparable systematics arise from hyperon-nucleon final-state cross sections ($-5/{+}2\,$MeV) and the exit-shift/gradient transport prescription ($-6\,$MeV). For $U_\Sigma$, the same $YN$ uncertainty biases the fit by $\mathcal{O}(150)\,$MeV; removing the $\Sigma^+$ tag does not cure this, because the $\Lambda$ momentum spectrum carries most $U_\Sigma$ information and is itself $YN$-sensitive. The low-density $U_\Lambda$ anchor is a robust handle, at several-MeV rather than sub-MeV precision. A joint fit with terrestrial and heavy-ion priors gives $M_{\rm max} = 2.21^{+0.04}_{-0.15}\,\,$Msun, set mainly by the external $c_\Lambda$ prior.

Quarkyonic matter resolves the neutron-star hyperon puzzle statistically: neutrons fill low-momentum $d$-quark phase space, shifting the $S=-1$ threshold from $\muB=M_Y$ to $2M_Y-M_N$ and suppressing residual softening by $1/\Nc^3$ in the Fujimoto--Kojo--McLerran (FKM) mechanism. We dress FKM's IdylliQ model with in-medium potentials, constrained by hypernuclear data and neutrino-induced hyperon FSI, and find: (i) the dressed onset, $\muB^{\rm onset}=(2M_Y{-}M_N)+2U_Y-\UN$, carries $U_Y$ at weight 2, with $dn_{\rm onset}/dU_Y\simeq0.3\,\nz$ per $10\MeV$, twice the leverage. (ii) A self-consistent neutron potential enters at weight $-2$, so protection needs $\UN(n_{\rm onset})\lesssim+96\MeV$. (iii) With leptons in $\beta$ equilibrium, the $\Sigma^-$ ($dds$) onset becomes $\mue\ge258\MeV+\US-\UN$, never reached inside a $2\,\Msun$ core: $\Sigma^-$ switches from first hyperon to forbidden and the $\Sigma$ ordering inverts. (iv) The $\kY\ge\kbu$ continuation gives TOV softening below $0.05\,\Msun$ in the FKM ansatz family and below $0.025\,\Msun$ for the realistic interacting star, $4$--$8$ below hadronic models. In the family this is a ceiling; generally it is a floor, since hyperons above $\kbu$ are omitted. (v) In an interacting low-density sector calibrated to $\Mmax=2.12\,\Msun$, core strangeness is controlled by $(\UL(\nz),c_\Lambda)$: at $\UL(\nz)=-28\MeV$, the maximum-mass star is hyperon-free once the supra-saturation $YNN$ turn-over exceeds a few-MeV threshold $c^*_\Lambda$. Projected SBND+DUNE FSI precision pins $\UL(\nz)$ but leaves $c_\Lambda$ -- to which neutrino data are blind -- decisive: with the heavy-ion prior, $P({\rm hyperon\mbox{-}free\ core})=0.90$, versus $0.89$ from priors alone, prior-dominated rather than measured. The sharpest observable is differential: $d\Mmax/dU_Y$ is an order of magnitude smaller than in mean-field models, discriminating the two resolutions.

We study the generation of the baryon asymmetry of the Universe via leptogenesis during the post-inflationary reheating epoch, considering reheating temperatures below the temperature of sphaleron freeze-out temperature. Within the framework of a monomial inflaton potential during reheating, we analyze three perturbative reheating scenarios in which the inflaton decays into (i) a pair of SM-like bosons, (ii) a pair of SM-like fermions, or (iii) exclusively into a pair of heavy right-handed neutrinos. For each case, we identify the regions of parameter space that successfully reproduce the observed baryon asymmetry consistently tracking the sphaleron interaction rate during reheating, while satisfying existing cosmological constraints. We also highlight the potential of future primordial gravitational wave observations to probe this class of scenarios.

We present the first self-force-based beyond-GR waveform model incorporating post-adiabatic orbital evolution for intermediate- and extreme-mass-ratio inspirals in theories of gravity with additional scalar fields. Focusing on quasi-circular inspirals into a non-spinning primary, we combine a first post-adiabatic (1PA) gravitational sector with leading-order scalar field effects and use Bayesian injection-recovery studies to assess the impact of waveform systematics on the inference of scalar charges with LISA. We find that neglecting 1PA effects in the gravitational sector can bias the inference of intrinsic binary parameters, while scalar-charge measurements remain robust across a wide range of mass ratios. In contrast, analysing signals from binaries in which the secondary carries a scalar charge using pure-GR templates leads to significant biases and underestimated uncertainties due to unmodelled correlations between the scalar charge and the binary parameters. We also investigate the role of secondary spin and find no significant correlation between the secondary spin and the scalar charge. Notably, up to a mass ratio of $10^{-4}$, the secondary spin itself remains unconstrained even in the pure-GR case, in contrast with previous claims in the literature. Finally, we show that modelling scalar emission with a leading-order dipolar post-Newtonian approximation -- for quasi-circular inspirals into a non-spinning primary -- introduces negligible systematic errors relative to fully relativistic scalar fluxes.

The nonrelativistic theory of nuclear matter (NM) based on Brussels-Skyrme interactions is employed to develop models for dense and neutron-rich matter within a Bayesian framework. We employ the following set of constraints: the four best-known nuclear empirical parameters, density dependence of the energy per particle in pure neutron matter (PNM), density dependence of the Landau effective mass ($m_\mathrm{eff}$) of neutrons in PNM and symmetric NM, and a lower limit on the maximum gravitational mass that neutron stars (NSs) can sustain. In addition, a number of ``sanity checks'' are added: the values of the speed of sound, neutron and proton Landau effective masses and Fermi velocities are constrained up to the central density of the most massive NS configuration and for isospin asymmetries $\delta=(n_n-n_p)/(n_n+n_p)$ ranging from 0 to 1. Our ensemble of models \emph{fully} explores the capacity of non-relativistic Brussels-Skyrme effective interactions to describe NM at densities exceeding several times the nuclear saturation density. This is a necessary step toward a better understanding of the properties of dense matter and possible correlations between the parameters of NSs and the parameters of NM. Due to pronounced U-shaped density-dependencies of $m_\mathrm{eff}$, all our models exhibit a non-monotonic ``rise-and-fall'' behavior of the thermal pressure ($p_\mathrm{th}$) as a function of density, which in extreme cases leads to $p_\mathrm{th} < 0$. This work is a generalization of [Beznogov and Raduta, Phys. Rev. C 110, 035805 (2024)].

The centre of mass (CoM) of compact binary coalescences (CBCs) occurring in the vicinity of a supermassive black hole, through interaction with an arbitrary third body (e.g., of stellar mass), or in a dense stellar environment, will undergo a time-varying line-of-sight (LOS) velocity. This in turn leads to a time-varying Doppler shift and corresponding modulations in the shape of the gravitational waves (GWs). The phase and amplitude corrections arising from constant LOS acceleration and its higher-order time derivatives are already known. Specifically, these effects lead to corrections to the GW waveform at $-4n$ post-Newtonian (PN) order, where $n$ is the $n^{th}$ time derivative of the LOS velocity. In the context of a circular or eccentric outer orbit of the CoM of the CBC, these effects can be thought of as approximations to the LOS velocity in the limit: observation duration $\ll$ period of the outer orbit. However, this condition is not necessarily always satisfied. In this {\it paper}, we present phase and amplitude corrections to the GW waveforms arising from a periodic non-relativistic LOS velocity for circular and eccentric outer orbits of the CBC's CoM. Specifically, these lead to phase and amplitude modulations at 4 PN order, and reduce to the known corrections for constant kinematic parameters under appropriate limits mentioned above. We also perform a Fisher matrix analysis to forecast constraints on the environment that is sourcing the time-varying LOS velocity, for various future ground and space-based detectors. We further show that constraints acquired using GW waveforms derived in this work improve significantly in comparison to those acquired from approximate methods valid for constant kinematic parameters.

We discuss what we call halo or galaxy root systems, collections of particle pathlines that show the infall of matter from the initial uniform distribution into a collapsed structure. The matter clumps as it falls in; projected through time, it produces filamentary density enhancements analogous to tree roots and branches, or branching river networks. This relates to the larger-scale cosmic web, but is defined locally about one of its nodes: a physical, geometric version of a merger tree. We find dark-matter-halo root systems on average to exhibit more roots and root branches for the largest cluster haloes than in small haloes, indicating their more complicated assembly, even in dark matter without gas physics. Also, we find that high spin manifests as curvier roots, and that many have mass contributions that start far away from central, compact protohalo cores. Root systems also show sensitivity to anisotropic infall, which we see some evidence for in a simulation with rather low box size.

We present a novel cosmological analysis based on the angular correlation dimension $D_2$ curve, a cumulative statistic derived from the two-point correlation function. Unlike traditional 3D approaches, angular $D_2$ is inherently less sensitive to nonlinear dynamical distortions, such as the small-scale Finger-of-God (FoG) effect. Using both MultiDark-Patchy and EZmock galaxy catalogs, we assess the scale-dependent impact of redshift-space distortions on $D_2$ and bias measurements. We demonstrate that the systematic errors associated with FoG modeling can be significantly reduced by restricting the analysis to appropriate minimum comoving angular scales of $\sim 1.25^{\circ} $, which corresponding to physical scales of $18$-$23\,h^{-1}\,\mathrm{Mpc}$ over the redshift range $0.46 \leq z \leq 0.74$ within the standard $\Lambda$CDM model. Since the observational estimative of $D_2(\theta)$ is not dependent on a cosmological model we obtain robust estimates of the galaxy bias and place competitive constraints on the physical matter density $\omega_m$. By applying this framework to SDSS DR12 and DR16 Luminous Red Galaxy data, we obtain $\omega_m = 0.137^{+0.041}_{-0.059}$ (1$\sigma$), which agrees with current CMB analyses. Our results highlight the potential of the angular $D_2$ curve as a model-independent and robust tool for cosmological parameter inference.

The LIGO-Virgo-KAGRA consortium has sporadically detected inspiral-dominated gravitational-wave events such as GW170817 and GW190425. These events offer an opportunity to constrain possible initial (residual) orbital eccentricities using purely inspiral template families. We detail the implementation of an LALSuite approximant, TaylorF2Ecck, which analytically models inspiral gravitational waves from non-spinning compact binaries in Post-Newtonian-accurate eccentric orbits and restricts the initial-eccentricity contributions to leading order. Specifically, our frequency-domain approximant consistently incorporates orbital, advance of periastron, and gravitational-wave emission effects fully up to 3PN order. We conduct detailed parameter-estimation studies of GW170817 and GW190425 using TaylorF2Ecck, following comprehensive sanity checks to validate model performance and investigate the influence of eccentricity and periastron advance in the relevant parameter space. The results indicate that the initial eccentricity at 20 Hz is negligible within the 90 percent credible intervals, and Bayes factors show no strong evidence favoring the eccentric waveform over the quasi-circular waveform. At such negligible initial eccentricities, comparisons between eccentric models with and without periastron advance show no clear signature of this effect, with no significant model-dependent shifts in the posterior distributions and no strong Bayes-factor evidence favoring one model over the other. Additionally, these detailed studies reveal the importance of incorporating initial-eccentricity contributions at least up to 3.5PN order and discuss its implications. We substantiate this inference by employing versions of the quasi-circular TaylorF2 approximant that incorporate Fourier phase contributions beyond the conventional 3.5PN order.

Magnetic fields are found in many astrophysical objects, ranging from galaxy clusters to the interstellar medium of galaxies and neutron stars. Strong surface magnetic fields are also observed in about 7% of OBA-type stars, and stellar mergers are the likely origin of at least some of them. We investigated magnetic-field amplification during the merger of a 9 and an 8 $M_\odot$ main-sequence star using 3D magnetohydrodynamic simulations from our previous work. We focused on the magnetic-field amplification mechanisms, field geometry, and the structure and properties of the resulting merger, in particular its rotational configuration. The merger produces a star-torus structure in which the core of the initially less massive star is surrounded by material from the primary. Initially, turbulent motions driven by Kelvin-Helmholtz and magneto-rotational instabilities generate small-scale magnetic fields. Subsequently, large-scale ordered azimuthal flows drive a larger-scale dynamo that amplifies and redistributes the magnetic energy to larger spatial scales, producing a remnant threaded by a strong large-scale magnetic field. The final magnetic configuration consists of intertwined poloidal and toroidal components, with a residual small-scale structure that resembles previously identified stable magnetic field equilibria. The amplification process is largely insensitive to the initial binary separation, numerical resolution, and seed magnetic-field strength. The central regions of the merger remnant rapidly approach solid-body rotation, transitioning to a Keplerian-like profile within the surrounding torus. Our results support stellar mergers as a viable pathway for the formation of strongly magnetic massive stars and potentially highly magnetized compact remnants, such as magnetic white dwarfs and magnetars.

Recent measurements of the baryon acoustic oscillations by the Dark Energy Spectroscopic Instrument (DESI), especially when combined with cosmic microwave background (CMB) and supernova data, favor a late-time dark energy equation of state that crosses $w=-1$, which has been argued to point toward non-minimal conformal coupling in Horndeski gravity. We test this interpretation by performing a non-parametric exploration of the minimally coupled, luminal Horndeski subclass known as kinetic gravity braiding (KGB). Using mochi_class and its manifestly stable effective field theory (EFT) basis implementation, we efficiently scan a broad class of models in which the EFT functions are allowed to vary freely in time, while enforcing the absence of ghost and gradient instabilities from the outset. We identify a set of KGB models that realize phantom crossing and remain broadly consistent with current probes of the background and linear large-scale structure, including CMB temperature and lensing power spectra, redshift-space distortions, cosmic shear, and the cross-correlation between galaxies and the Integrated Sachs-Wolfe effect. Our results demonstrate that viable phantom-crossing solutions exist without conformal coupling, motivating future full Bayesian analyses of this model class with non-parametric EFT priors.

We compute the cosmic stellar, dust and neutral gas mass history at $0<z\lesssim3$ using ProSpect spectral energy distribution modelling of $\approx 800 \, 000$ galaxies in the Galaxy and Mass Assembly (GAMA) survey and the Deep Extragalactic VIsible Legacy Survey (DEVILS). The cosmic dust mass history broadly follows the shape of the cosmic star formation history; though, the decline is slower, suggestive of a slowing rate of dust growth and destruction as the star formation declines past its peak at $z\approx 2$. Neutral gas masses were estimated by scaling the dust masses by the metallicity-dependent dust-to-gas ratio. The neutral gas mass density as traced by the dust is an average of $\approx 0.7$ dex lower than that measured from $21$cm experiments, most likely due to differences in the spatial scales inhabited by dust and HI. Folding in measurements of the supermassive black hole mass density obtained previously with similar data and methods, we present a self-consistent census of the baryons confined to galaxies. Stars, neutral gas, SMBHs and dust contained within the optical radii of galaxies account for $\approx 5$ per cent of the baryons. Most of the remaining $\approx 95$ per cent of baryons must be ionised and dispersed throughout the interstellar, circumgalactic and intergalactic media within, around and between galaxies.

We present multiwavelength observations and analysis of six luminous fast blue optical transients (LFBOTs) discovered in Zwicky Transient Facility (ZTF) survey data. We identified these LFBOTs from their fast light-curve evolution ($t_{1/2}\leq 12 $d), blue colors at peak brightness ($g-r\leq-0.5 $mag), a visible host galaxy, high optical luminosity ($M_g<-20$), and an X-ray or radio detection. With the exception of AT2024aehp (ZTF24abygbss), these transients exhibit peaks in their $10\,$GHz radio light curves at $t_{\text{rest}} \approx 50-100$ d, with peak radio luminosities ranging from $10^{38}-10^{40}$ erg s$^{-1}$. Modeling the radio emission as synchrotron radiation indicates a fast ($v=0.1-0.3c$) shock in a dense ($n_e\approx10^{3}-10^{4}$ cm$^{-3}$) medium. The X-ray emission varies by $\approx2$ orders of magnitude in luminosity ($10^{42}-10^{44}$ erg s$^{-1}$) at $t_{\text{rest}}\sim20 $d. Analysis of the host-galaxy photometry and spectroscopy for each transient shows that they are predominantly nonnuclear (a few kpc offset) with star-forming host galaxies of stellar masses $10^{9}-10^{11} ,M_\odot$. Unlike all other LFBOTs to date, AT2024aehp exhibited a luminous ($M<-19 $mag) plateau in the optical light curve; spectra during this plateau phase showed a featureless blue continuum. The $6-15$ GHz radio emission of AT2024aehp brightened by over an order of magnitude from $t_{\text{rest}} \approx70 $d to $t_{\mathrm{rest}} \approx130 $d. The mostly consistent radio behavior between optically selected LFBOTs implies a similar circumburst medium, leading us to prefer a progenitor scenario in which mass is lost in a consistent way shortly prior to the terminal event, such as a massive star merging with a compact object.

IceCube recently reported the observation of TeV neutrinos from the nearby Seyfert galaxy NGC~1068, and the corresponding neutrino flux is significantly higher than the upper limit implied by observations of GeV-TeV gamma rays. This suggests that neutrinos are produced near the supermassive black hole, where the radiation density is high enough to obscure gamma rays. We use a set of muon neutrinos with interaction vertices inside the detector, which have good sensitivity to sources in the Southern sky, from IceCube data recorded between 2011 and 2021. We then search for individual and collective neutrino signals from 14 Seyfert galaxies in the Southern Sky selected from the Swift Burst Alert Telescope (BAT) AGN Spectroscopic Survey. Using the correlations between keV X-rays and TeV neutrinos predicted by disk-corona models, and assuming production characteristics similar to NGC~1068, a collective neutrino signal search reveals an excess of $6.7_{-3.2}^{+4.0}$ events, which is inconsistent with background expectations at the 3$\sigma$ level of significance. In this paper, we present new independent evidence that Seyfert galaxies contribute to the extragalactic flux of high-energy neutrinos.

Gravitational wave (GW) spectral sirens offer a promising method for measuring cosmological parameters using GW data only - without relying on external redshift information such as electromagnetic counterparts or galaxy catalogs - by exploiting distributional features in the population of GW sources. The advent of third-generation detectors like the Einstein Telescope (ET) will provide catalogs three orders of magnitudes larger than current ones, raising questions about the scalability and robustness of existing inference pipelines. We present a blinded mock data challenge that tests three public pipelines with distinct numerical implementations, namely, $\texttt{ICAROGW}$, $\texttt{CHIMERA}$, and $\texttt{pymcpop-gw}$, on simulated ET observations containing the best $\mathcal{O}(10^4)$ binary black hole mergers that can be observed in 1 year. We assess their computational performance, validate their agreement in a blinded setting, and forecast cosmological constraints. We find that, thanks to GPU acceleration, these pipelines can process the events expected from ET within a manageable timeframe. All pipelines recover consistent cosmological and population parameters. Assuming a flat $\Lambda$CDM model, we measure $H(z)$ at $z\sim1.5$ with 2.4% precision, and achieve a mean precision on $H(z)$ of 2.8% across $0.7<z<1.8$ with a catalog of $\sim 12,000$ high-S/N events. This corresponds to joint constraints of $\sim 10%$ on $H_0$ and $\sim 26%$ on $\Omega_{\rm m,0}$. We also identify the events that contribute mostly to constraining cosmological parameters, showing that low-distance sources near population features drive the constraining power on all cosmological parameters, while higher-distance events primarily constrain $\Omega_{\rm m,0}$. Our results establish a validated, performance-tested framework for spectral siren cosmology in the era of third-generation GW observatories.

The upcoming decade of observational cosmology will be shaped by large sky surveys, such as the ground-based LSST at the Vera C. Rubin Observatory and the space-based Euclid mission. While they promise an unprecedented view of the Universe across depth, resolution, and wavelength, their differences in observational modality, sky coverage, point-spread function, and scanning cadence make joint analysis beneficial, but also challenging. To facilitate joint analysis, we introduce A(stronomical)S(urvey)-Bridge, a bidirectional generative model that translates between ground- and space-based observations. AS-Bridge learns a diffusion model that employs a stochastic Brownian Bridge process between the LSST and Euclid observations. The two surveys have overlapping sky regions, where we can explicitly model the conditional probabilistic distribution between them. We show that this formulation enables new scientific capabilities beyond single-survey analysis, including faithful probabilistic predictions of missing survey observations and inter-survey detection of rare events. These results establish the feasibility of inter-survey generative modeling. AS-Bridge is therefore well-positioned to serve as a complementary component of future LSST-Euclid joint data pipelines, enhancing the scientific return once data from both surveys become available. Data and code are available at this https URL.

Cosmic-ray pitch-angle transport in magnetohydrodynamic (MHD) turbulence is governed by the interplay between magnetic mirroring and gyroresonant scattering. We develop a guiding-center (GC) Langevin model with explicit mirror drift and gyroresonant diffusion to describe the pitch angle evolution. This model accurately captures our test-particle simulation results in three-dimensional MHD turbulence, driven both solenoidally and compressively. We find that magnetic mirroring can drive anomalous pitch-angle diffusion at large pitch angles (including $90^\circ$) with non-Markovian memory effects, which arises from trapping of particles in magnetic wells. Gyroresonant scattering controls the escape rate from these wells. Across $M_{\rm A}$, large-pitch-angle particles are jointly regulated by mirror trapping and gyroresonant escape, exhibiting a transition from anomalous to normal diffusive pitch-angle transport as scattering strengthens, whereas small-pitch-angle particles remain gyroresonance-dominated and diffusive throughout. The pitch angle transport is found to be dominated by the compressible perturbations with marginal influence from Alfvén modes. In compressible turbulence with realistic damping accounted for, transit time damping (TTD) treatment fully recovers mirror interactions.

Obtaining robust galaxy number counts is crucial for understanding galaxy evolution, and submillimetre counts in particular have proven valuable for revising subgrid physics models in cosmological simulations. In confusion-limited surveys, which are common at these wavelengths, statistical methods such as $P(D)$ fluctuation analysis are required to recover counts of faint, unresolved galaxies. However, the standard $P(D)$ framework assumes that galaxies are Poisson-distributed, whereas in reality galaxies are clustered. Using simulations, we demonstrate that this clustering systematically biases $P(D)$-derived number counts, and present an empirical method that simultaneously measures and corrects for this bias by combining the 1- and 2-point statistics in the map, thereby maximising the information extracted from the data. Applying this method to deep Herschel-SPIRE observations of the GOODS-N field, we provide revised galaxy number counts at 250, 350 and 500 $\mu$m. Our results indicate that at 500 $\mu$m clustering inflates the apparent counts by a factor of 1.6 around 10 mJy and slightly suppresses the faintest sub-mJy counts, with milder effects at 350 $\mu$m and 250 $\mu$m owing to the smaller beam sizes. This methodology is broadly applicable to other confusion-limited data sets with well-characterised beam and noise properties, including Spitzer, SCUBA-2, and the upcoming CCAT, enabling unbiased exploitation of the full statistical information in many surveys in the mid-IR to radio wavebands.

We present spatially resolved parsec-scale measurements of nuclear conditions (gas density and kinetic temperature) relevant for black hole accretion rate predictions in the Seyfert 2 galaxy, NGC 1068. We inject these parameters into the prescription for a Bondi-like accretion model, then compare the resulting accretion rate prediction to the empirical accretion rate derived from hard X-ray observations. Cosmological simulations have spatial resolution ranging from $\sim$10 pc to $\sim$kpc scales, and so for reasonable comparison we test these accretion rate predictions in pixel-sized radial steps out to 500 pc. Compared to warm H$_2$ gas, CO gas is the dominant mass carrier close to the SMBH. We find that the Bondi accretion rate ($\dot{\mathrm{M}}_{\mathrm{Bondi}}$) of cold molecular gas alone (measured using CO) overestimates the true accretion rate by up to 14 dex in a small aperture (r$\lesssim$5 pc) around the black hole, and by at least 8 dex inside large apertures (r$\lesssim$500 pc). These results are the first in a series of direct tests of accretion rate prescriptions, and they suggest that using a Bondi accretion formalism to model supermassive black hole accretion in Seyfert 2 galaxies may lead to overestimated accretion rates in simulations.

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.

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 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.

Fast Radio Bursts (FRBs) are millisecond-duration, highly energetic radio transients of uncertain origin. Repeating FRBs provide an excellent population for investigating their nature, particularly through studies of parameter evolution. Out of the 63 repeaters monitored by CHIME, we select the 19 sources with more than ten detected bursts, and examine their long-term dispersion measure (DM) evolution. Seven sources show statistically significant DM evolution and are classified as the golden sample. Of these, five exhibit a decreasing DM trend and two shows an increasing trend. We then perform a binomial test under the null hypothesis that decreasing and increasing DM variation trends have equal probabilities. The current combined sample, including our golden sample and additional repeaters with reported DM change rate from the literature, gives a p-value of 0.033, supporting that decreasing DM trends are more common in the repeating FRB population. This statistical result is consistent with scenarios in that the local electron density around repeaters generally decreases with time, for example due to expansion of a young supernova remnant (SNR). Finally, within the SNR expansion model, we provide an illustrative estimate of the SNR contributions to the DM for different ejecta masses.

Three-form fields provide a theoretically well-motivated framework for dark energy, arising in higher-dimensional theories and exhibiting a rich cosmological phenomenology. We investigate a minimally coupled three-form dark energy model with a Gaussian potential and constrain it using current cosmological observations, including CMB shift parameters, DESI DR2 baryon acoustic oscillation measurements, Pantheon+ supernovae with and without SH0ES calibration, cosmic chronometers, and gamma-ray bursts. Parameter estimation is performed within a Bayesian Markov-chain Monte Carlo framework, while model comparison relies on several information criteria and the Bayesian evidence, as well as tension statistics. We find that the three-form model provides a viable and competitive description of the expansion history of the Universe. It is mildly preferred over $\Lambda$CDM for the combination of early and late-time datasets that are heavily tensioned (CMB+BAO and Pantheon+SH0ES). This preference decreases to neutrality for the other, less tensioned combination of early and late-time data, while for individual early-time or late-time datasets analysed separately, the information criteria are neutral or favour $\Lambda$CDM. This suggests that the additional degrees of freedom of the three-form field may help accommodate cosmological observations of different origins within a common framework. The reconstructed dark energy dynamics exhibit a characteristic phantom phase at intermediate redshifts while approaching a cosmological-constant-like behaviour at early and late times, providing a distinctive observational signature. Although the model does not significantly alleviate the Hubble tension despite allowing higher values of $H_0$, it remains consistent with current observations and offers a well-motivated alternative to $\Lambda$CDM whose predictions can be tested by future cosmological surveys.

The FAST All Sky HI Survey (FASHI) conducted with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) has mapped $\sim 19500\,\mathrm{deg}^2$ of the sky north of DEC $= -14^{\circ}$, detecting $156411$ extragalactic HI sources at $z< 0.09$ with a median sensitivity of $0.57\,\mathrm{mJy}\,\mathrm{beam}^{-1}$ at a velocity resolution of $6.4\,\mathrm{km}\,\mathrm{s}^{-1}$. The survey achieves unprecedented depth and area coverage, significantly improving upon previous single-dish surveys. Through a detailed completeness analysis that accounts for the survey's non-uniform sensitivity and line-width dependence, we construct a robust HI mass function (HIMF) using a completeness-corrected sample of over $109000$ sources. The HIMF is robustly constrained down to $M_{\mathrm{HI}}\sim 10^{6.2}\,M_{\odot}$. When systematic uncertainties are included, the HIMF is well described by a single-Schechter function with a characteristic mass $\log (M_{*} / h_{70}^{-2}M_{\odot}) = 9.89\pm 0.02$, low-mass end slope $\alpha = -1.31\pm 0.02$, and amplitude $\phi_{*} = (6.38\pm 0.49)\times 10^{-3}\,h_{70}^{3}\,\mathrm{Mpc}^{-3}\,\mathrm{dex}^{-1}$. The derived cosmic HI density is $\Omega_{\mathrm{HI}} = (4.71\pm 0.03_{\mathrm{stat}}\pm 0.40_{\mathrm{sys}})\times 10^{-4}\,h_{70}^{-1}$. FASHI provides the most extensive and sensitive HI catalog to date, establishing an important benchmark for studies of gas accretion, galaxy evolution, and large-scale structure in the local universe.

Understanding stellar magnetic activity is central to exoplanet science in two ways: it sets the dynamic astrospheric boundary condition governing planetary space environments, and it is the primary obstacle to exoplanet detection and characterisation, since magnetically driven variability imprints correlated quasi-periodic signals across detection time series. In cool stars, MHD-dynamo-generated fields emerge at the photosphere as bipolar regions, drive chromospheric and coronal heating, modulate irradiance and wind, and power flares and coronal mass ejections. Spatial scales range from individual flux tubes to global coronal configurations, and temporal scales from minutes to decades and beyond, requiring observational and theoretical tools of correspondingly wide scope. We review observational manifestations and physical models of magnetic activity in stars with outer convective envelopes, addressed to the exoplanet community. We develop the solar-stellar connection through the 'Sun in Time' framework and a sequence of solar analogues serving as evolutionary snapshots of a solar-mass star over several Gyr. We survey photospheric, chromospheric, and coronal activity diagnostics across timescales, together with forward-modelling tools translating surface field distributions into signals at or above the level of exoplanet detection. Empirical rotation-activity relationships and their physical interpretation are examined across all three atmospheric layers. Surface reconstruction techniques are assessed for their diagnostic reach and limitations. The evolution of magnetism in solar-like stars is discussed as context for habitability and as a window to other worlds. We close with an account of how stellar magnetism sculpts the astrospheric environment and affects close-in exoplanets, followed by a synthesis of outstanding issues and an outlook on future prospects.

The symbiotic recurrent nova (SyRNe) TCrB (T-Coronae Borealis) is perhaps the most famous example of the group of known four symbiotic nova systems, for which at least two previous nova eruptions are known and accurately recorded: in 1866 and 1946. B.E. Schaefer (2023) has identified the dates of two other previous eruptive events: in 1787 and 1217. Its peak magnitude V was found to be 2.50+-0.10, making it the brightest of its class. In its quiescent phase, TCrB is the brightest of all known novae, with a mean magnitude of 9.8. Careful studies, especially photometric ones, have led to different predictions for the next nova eruption, taking into account the recurrence times extrapolated from previous eruptions, which an average value about 80 years. Schaefer, in particular, has produced various forecasts, including one made in 2023 based on B and V light curves for the period: 1842-2022, which predicts the next nova eruption should occur in 2025.5+-1.3 and is therefore still valid today. Using the Schaefer's remarkable work in accurately determining the key physical parameters that drive the dynamics of the TCrB symbiotic system, we propose here a new semi-empirical method to derive the variations in the nova recurrence time, Trec, and thus obtain a forecast estimate for the next eruption for the date: 26-Feb-2027, which is currently compatible and consistent with the observed behavior and would also justify the supposed "delay" for the next event of this nova as commented by various authors.

We present a photometric and spectroscopic study of the superluminous Type Ia supernova SN 2022erq. Its early spectra, dominated by iron-group elements with weak intermediate-mass features, might indicate highly efficient nuclear burning, broadly similar to that inferred for some overluminous SNe Ia. The rapid emergence and persistence of narrow Balmer emission lines superposed on this iron-rich spectrum provide clear evidence of long-lived interaction with a hydrogen-rich circumstellar medium (CSM), establishing SN 2022erq as a member of the rare Ia-CSM class. SN 2022erq reached a peak bolometric luminosity of about 8 x 10^43 erg/s and exhibited an exceptionally slow post-peak decline, indicating that its light curve is dominated by long-duration ejecta-CSM interaction. By combining H-alpha diagnostics with bolometric light-curve modeling, we reconstruct the pre-explosion mass-loss history of the progenitor. The mass-loss rate escalated by one order of magnitude over the final decades, rising from about 0.04 to about 0.6 solar masses per year. This surge produced a massive, extended CSM shell of about 3 solar masses out to about 3.5 x 10^16 cm. The young stellar environment (about 100 Myr) together with this substantial, extensive CSM points to a progenitor system consisting of a white dwarf and an intermediate-mass companion that underwent increasing mass loss prior to explosion.

We show that angular cross-correlations between distance indicators and galaxy redshift catalogues, when interpreted within an assumed cosmological model, can constrain potential biases in distance measurements induced by calibration systematics. As a test case, we consider a simple scenario in which a constant calibration offset $\Delta M$ shifts all observed distances by a multiplicative factor, and we produce Fisher forecasts for the constraining power on $\Delta M$ and $H_0$ from existing and upcoming surveys. In our most optimistic scenario, based on the expected number of SN Ia observed by LSST and the DESI final data release, we find $\sigma_{\Delta M} \approx 0.05$ and $\sigma_{H_0} \approx 1.81~\mathrm{km~s^{-1}~Mpc^{-1}}$. This has important implications for the Hubble tension, since explaining the discrepancy purely as a calibration systematic in low-$z$ measurements would require $\Delta M \approx 0.13$.

Primordial non-Gaussianities (PNGs) are a broad class of features in the initial density field that are connected to the particle physics of the early Universe. Measuring the amplitude of these features directly constrains fundamental physics from these earliest epochs and lends insight into energy scales that cannot be probed with terrestrial experiments. Using a new class of simulation methods, we propagate these signatures to their impact on the formation of non-linear structure and quantify the constraining power in non-Gaussian summary statistics of weak lensing, thermal Sunyaev Zeldovich (tSZ), and X-ray surveys. We use semi-analytic baryon models that consistently include astrophysical effects across all these observables, and use foreground modeling approaches that explicitly fold in correlations between the various components. We find that the tSZ and X-ray fields have significant information about PNGs, and additionally can help self-calibrate a broad set of nuisance parameters/models by breaking parameter degeneracies. Using the second and third moments of the lensing, tSZ, and X-ray fields, we find a factor of 2 improvement in PNG constraints relative to using lensing alone. Larger improvements are expected when including more scales and other complementary summary statistics. Our multi-wavelength map maker can be found at this https URL. The simulations and software pipelines used in this analysis are publicly available.

Space- and lunar-based interferometry are moving from aspiration toward a concrete landscape of mission studies, pathfinders, and staged architectures. This invited review surveys that landscape across two principal platform pathways: free-flying and lunar-surface interferometers - plus structurally connected designs and hybrid space-VLBI arrays. I trace how the science target sets the wavelength regime and angular resolution, which in turn fix the baseline, architecture, and implementation risk. Mid-infrared nulling concepts such as LIFE target temperate exoplanets through thermal-emission spectroscopy; lunar far-side radio arrays (FARSIDE, FarView) open the low-frequency Universe from the only radio-quiet site in the inner Solar System; lunar UV/optical concepts (Artemis-enabled Stellar Imager, MoonLITE) revisit imaging of stellar surfaces and open a path to microarcsecond astrometry for the dynamical masses that Habitable Worlds Observatory target selection requires; far-infrared interferometers (SPIRIT/SPICE), space VLBI (BHEX), and X-ray concepts extend the reach to planet formation, high-redshift galaxies, and black-hole physics; and lunar laser interferometry (LILA) applies the lunar platform to mid-band gravitational waves, measuring strain rather than angular position. Across this range, the concepts share enabling technologies - precision formation flying, absolute metrology, beam combination and nulling, cryogenics, and autonomous deployment - maturing largely as byproducts of flagship programs, a dynamic that increasingly governs which concepts become missions. I summarize the pathways in baseline, wavelength, science return, deployment strategy, and risk, and close with the decisions of the coming decade: pathfinder sequencing, technology tall poles, and the funding models that can carry technologies from laboratory demonstration to flight readiness.

The catalog from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Public Data Release 1 (PDR1) contains half a million emission-line-selected [OII] galaxies spread across $540~\mathrm{deg}^2$ at $z \le 0.48$ from HETDEX's unprecedented untargeted spectroscopic survey. In this paper, we construct volume-limited samples from PDR1 in three luminosity bins across the two main fields: "Spring'' and "Fall''. The numbers of galaxies in the bins range from 11,354 to 64,794 and number densities, $\bar{n}\simeq (2-5)\times10^{-3}~h^3~\mathrm{Mpc}^{-3}$, are higher than those of typical cosmological spectroscopic surveys of emission-line galaxies by a factor of five to ten. The monopole and quadrupole power spectra derived from these samples are in excellent agreement with the mock power spectra from the Uchuu simulation based on a flat $\Lambda$CDM model and the cosmological parameters from the Planck cosmic microwave background data, at all wavenumbers used for the measurement ($0.01<k<0.7~h~\mathrm{Mpc}^{-1}$). We find that the power spectrum amplitudes are consistent with a characteristic dark matter halo mass of $\log(M_0~[h^{-1}M_{\odot}])\simeq 11.9$-$12.3$, with the halo mass showing a weak dependence on [OII] luminosity, $M_0\propto L^a$, increasing with a slope of $a = 0.37\pm0.10$. The best-fit mock suggests that approximately 13 percent of the [OII] galaxies in our sample reside in subhalos. The new, high-density tracers of the underlying matter distribution presented in this paper provide precise measurements of clustering in a low-redshift regime sensitive to the late-time growth of structures. These samples will form the basis for forthcoming analyses of the redshift-space distortion effect, galaxy-halo connection, and cross-correlations with external low-redshift probes.

We report the first detection of radio pulsations from PSR J2238+5903, a gamma-ray pulsar spatially coincident with the extended TeV source 1LHAASO J2238+5900. Our 3000 s FAST L-band observation reveals a weak periodic signal at the known Fermi-LAT spin period, with $P=162.76568$ ms and $\mathrm{DM}=247.5\pm3.0~\mathrm{pc~cm^{-3}}$. The signal is independently confirmed by both FFT-based and Fast Folding Algorithm searches. The radiometer equation gives a flux density of $S_{1250}\simeq3\,\mu$Jy, placing PSR J2238+5903 among the faintest radio-detected Fermi pulsars. Interpreting the DM with Galactic electron-density models gives $d_{\rm DM}=7.4\pm3.9$ kpc. At this distance, the LHAASO WCDA 39\% containment radius corresponds to a characteristic diameter of $\sim132$ pc, and the $>1$ TeV luminosity is $L_{\rm TeV}\simeq7.1\times10^{34}$ erg s$^{-1}$, about 8\% of the pulsar's spin-down power. The radio DM thus provides the first pulsar-specific distance constraint for assessing whether 1LHAASO J2238+5900 is a young relic-PWN / TeV-halo transition system.

Observational data on type IIn supernova SN 2015da are revisited to clarify some ambiguous issues of this phenomenon. The H alpha--emitting site is found to switch around day 90 from the circumstellar matter to the unshocked ejecta. This picture makes it possible to recover the expansion velocity of late time ejecta and to locate the dust formation in the inner zone of unshocked this http URL bolometric light curve and expansion velocities combined with modelling the circumstellar interaction imply that the supernova exploded with an energy of $\gtrsim 4\times10^{51}$ erg inside the circumstellar envelope with the mass of $\approx 14$ Msun. The recovered density of the circumstellar matter is consistent with the Thomson optical depth inferred from H alpha modelling on day this http URL observed circumstellar envelope is produced by an average mass loss rate of 0.035 Msun/yr during 400 yr before the supernova explosion.

We present a sample of coherent and stable photometric period determinations for cataclysmic variables, based on TESS photometry through sector 102. We analyzed a total of 1557 cataclysmic variable stars and detected periodic variations in 1362 objects, including 286 eclipsing or ellipsoidal-variation systems, 63 polars, and 135 intermediate polars. In particular, we present the first determination of the optical variability period for 565 cataclysmic variables. Due to the 21x21" pixel size of TESS, we tested whether the variability was coming from the cataclysmic variable and not from a nearby star. For the intermediate polars, we detected spin periods in addition to orbital periods for 83 systems. We detect a clear period gap between ~2 and ~3 h in the eclipsing sample, consistent with previous work. The gap remains for the complete sample of photometric variability periods. There is no apparent gap in the orbital period distribution for intermediate polars. Finally, the median of the photometric period distribution of our complete sample of cataclysmic variables is 3.681 h. Comparing this to the distribution of rotation periods for likely single white dwarfs, we find a similar range, with a median photometric period of 6.803~h.

Smooth window functions are often applied to strain data when inferring the parameters describing the astrophysical sources of gravitational-wave transients. Within the LIGO-Virgo-KAGRA collaboration, it is conventional to include a term to account for power loss due to this window in the likelihood function. We show that the inclusion of this factor leads to biased inference. The simplest solution to this, omitting the factor, leads to unbiased posteriors and Bayes factor estimates provided the window does not suppress the signal for signal-to-noise ratios $\lesssim O(100)$, but unreliable estimates of the absolute likelihood. Instead, we propose a multi-stage method that yields consistent estimates for the absolute likelihood in addition to unbiased posterior distributions and Bayes factors for signal-to-noise ratios $\lesssim O(1000)$. Additionally, we demonstrate that the commonly held wisdom that using rectangular windows necessarily leads to biased inference is incorrect.

Cosmological data provides us two key constraints on dark matter (DM): it must have a particular abundance, and it must have an adiabatic spectrum of density perturbations in the early universe. Many different cosmological scenarios have been proposed that establish the abundance of axion DM in qualitatively different ways. In this paper we emphasize that, despite this variety of backgrounds, the perturbations in axion DM can be understood from universal principles. How does a feebly interacting axion field acquire perturbations proportional to those of photons? How do the isocurvature power spectrum and non-Gaussianity depend on the background evolution of the universe? We answer these questions for a completely general choice of cosmological background and temperature-dependent axion potential. We show that the most general solution to the axion field equation on super-horizon scales is entirely determined by the family of background solutions for different initial field values $\theta_{\rm ini}$. This holds for both the component in the field perturbation solution contributing to the DM isocurvature perturbation (enhanced at late times by the sensitivity of the DM abundance to the initial condition, $\partial \Omega_a / \partial \theta_{\rm ini}$, which can be large for initial conditions near the hilltop), and the other component that contributes to the DM curvature perturbation. In particular, we explain that an unperturbed axion field in the early universe evolving into one with nontrivial adiabatic perturbations is guaranteed by Weinberg's theorem on adiabatic modes. These results have been derived before with various assumptions, such as a radiation dominated background or a quadratic potential. Our aim is to give a clear, simple derivation that is manifestly independent of those assumptions, and thus can be applied to any cosmological axion scenario.

The scattering of dark matter particles within the Sun's hot plasma can lead to the acceleration of dark matter, producing a high-energy solar-reflected DM flux detectable in ground-based experiments. In the vector portal model, the dark matter has a sub-MeV-scale mass, and interactions between the dark matter and Standard Model particles are mediated by a hidden vector field--referred to as a dark photon--which kinetically mixes with the conventional photon through a small mixing angle. Furthermore, the solar plasma generates intense magnetic fields. Due to the photon-dark photon mixing, this simultaneously sources a ``dark magnetic field". For sufficiently low dark photon masses, this dark magnetic field is capable of deflecting dark matter particles traversing the Sun. We found that if the dark magnetic force is sufficiently strong, the dark magnetic field becomes a wall, preventing the dark matter particles from reaching the deep core region, suppressing their reflected flux. This scenario corrects the sensitivity of the solar-reflected dark matter detection, offering critical insights for ground-based experiments aiming to probe dark matter.

Fast and reliable inference of gravitational-wave source parameters is crucial for analyzing large catalogs that are reaching the size of hundreds of detections, and for identifying short-lived electromagnetic counterparts. Neural posterior estimation has emerged as a powerful inference method, where the model is trained on simulated gravitational-wave data at considerable computational cost, but thereafter enables extremely fast and inexpensive inference at test time. Here, we extend this approach by incorporating domain-specific physical insights and methods in the model architecture. These include compressing the data by heterodyning against a reference waveform chosen via approximate likelihood maximization, removing parameter degeneracies through tailored coordinate systems, and eliminating known multimodalities by folding the parameter space. As a result, the network is approximately equivariant to changes in the source parameters, and achieves a reduced training cost and improved model interpretability. Our implementation, called labrador, can be trained end-to-end on a 1-day timescale on $\sim 10^2$ CPU cores and a V100 GPU, achieving a median importance-sampling efficiency of 1% on quadrupolar, aligned-spin signals in a broad mass range (chirp mass $\mathcal{M} \in 1\text{-}50\,\mathrm{M}_\odot$, mass ratio $q > 0.1$). labrador is the first neural inference code to achieve extensive coverage of long-duration signals with secondary masses $m_2 < 10\,\mathrm{M}_\odot$, rendered possible by its equivariance property. Among our novel contributions is a numerically stable procedure that enables neural posterior estimation when the simulation and inference priors differ.