The Pierre Auger Observatory has a public data policy following the FAIR principles (Findable, Accessible, Interoperable, and Reusable). We aim to share the data with the scientific community as part of the multi-messenger effort at different levels and for educational activities to engage the general public. Following the first portal created in 2007, a new portal hosted at \url{https://opendata.auger.org} was established in February 2021. The portal is regularly updated and comprises 10\% of the recorded cosmic-ray data organized in various datasets, each with a specific DOI provided by Zenodo. Moreover, a catalog with the 100 most energetic events is available. The portal adopts a ``dual'' concept, offering not only the download of public data but also a series of Jupyter notebooks. These notebooks allow the general public to reproduce some of the most important results obtained by the Pierre Auger Collaboration and understand the main mechanisms governing the development of the extensive air showers produced by the interaction of cosmic rays in the Earth's atmosphere. In 2023, the Pierre Auger Observatory joined the International Particle Physics Outreach Group (IPPOG). The successful debut enrolled 550 high-school students at 12 research institutions from 5 countries and was repeated this year, embracing yet more students and countries worldwide. During this day, the participants attend seminars about cosmic rays and are asked to reconstruct subsets of public data events using an Auger 3-D event display. Finally, they participate in a Zoom session with scientists at the Auger site.

It has been previously demonstrated [Panov et al. Physics of Atomic Nuclei 84(2021)1037] that the TAIGA-HiSCORE Cherenkov array, originally built for cosmic ray physics and ultrahigh-energy gamma-ray astronomy studies using the extensive air shower method, can be used in conventional optical astronomy for wide-field searches for rare nanosecond optical transients of astrophysical origin. The FOV of the facility is on the scale of 1~ster, and it is capable of detecting very rare transients in the visible light range with fluxes greater than approximately 3000~quanta/m$^2$/10~ns (10~ns is the apparatus integration time) and pulse durations of 10\,ns. Among the potential sources of distant nanosecond optical transients are the evaporation of primary black holes, magnetic reconnection in the accretion disks of black holes, and signals from distant lasers of extraterrestrial civilizations. The paper describes the methods and results of the search for optical transients using the TAIGA-HiSCORE Cherenkov array from 2018 to 2022 (four winter seasons of data collection). No reliable astrophysical candidates for optical transients were found. We set an upper bound on the flux of the searched events as $\sim 1\times10^{-3}$\,events/ster/h.

The halo of our Galaxy is populated with a significant number of high-velocity clouds (HVCs) moving with a speed up to $500$ km/s. It is suggested that these HVCs might contain a non-negligible fraction of the missing baryons. The main aim of the current paper is to estimate the baryonic mass of the Milky Way halo in the form of HVCs in order to constrain a fraction of missing baryons in the form of these clouds. Such findings would give substantial help in the studying halo dynamics of our Galaxy. We first estimate the HVCs distance. We consider the most recent and updated HVC catalog, namely the Galactic All Sky Survey (GASS), which, however, covers the southern sky declinations, south of $b \leq 60^\circ$. Following a model presented in the literature, we assume that most of the HVCs (not all of the HVCs in the Milky Way) were ejected from the Magellanic Clouds (MCls) which is at a distance of about 50 kpc. We assume that the HVCs have a temperature in the range of about $10^2 - 10^4$ K, and are distributed in the Galactic halo as the Navarro-Frenk-White (NFW) profile. Since the GASS survey covers a small portion of the sky, we estimate the number of missing clouds by using Monte Carlo (MC) simulations. The next step will be to estimate the total mass of the Milky Way contained in the form of these HVCs. The total mass resulted to be $\sim (7 \pm 2) \times 10^{9} M_{\odot}$ in the form of HVCs and compact high-velocity clouds (CHVCs).

High energy neutrino astronomy has seen significant progress in the past few years. This includes the detection of neutrino flux from the Galactic plane, as well as strong evidence for neutrino emission from the active galaxy NGC 1068, both reported by IceCube. New results start coming from the two km$^3$-scale neutrino telescopes under construction in the Northern hemisphere: KM3NeT in the Mediterranean Sea and Baikal-GVD in Lake Baikal. After briefly reviewing the status of the field, we present the current status of the Baikal-GVD neutrino telescope and its recent results, including observations of atmospheric and astrophysical neutrinos.

Recent observations from the James Webb Space Telescope (JWST) have uncovered an unexpectedly large abundance of massive, UV-bright galaxies at high redshifts $z \gtrsim 10$, presenting a significant challenge to established galaxy formation models within the standard $\Lambda$CDM cosmological framework. Cosmic strings, predicted by a wide range of particle physics theories beyond the Standard Model, provide a promising potential explanation for these observations. They may act as additional gravitational seeds in the early universe, enhancing the process of high-redshift structure formation, potentially resulting in a more substantial population of massive, efficiently star-forming galaxies. We numerically investigate this prediction in large-volume hydrodynamical simulations using the moving-mesh code AREPO and the well-tested IllustrisTNG galaxy formation model. We evaluate the simulation results in the context of recent JWST data and find that sufficiently energetic cosmic strings produce UV luminosity and stellar mass functions that are in slightly to substantially better agreement with observations at high redshifts. Moreover, we observe that the halos seeded by cosmic strings exhibit a greater efficiency of star formation and enhanced central concentrations. Interestingly, our findings indicate that the simulations incorporating cosmic strings converge with those from a baseline $\Lambda$CDM model by redshift $z \sim 6$. This convergence suggests that the modified cosmological framework effectively replicates the successful predictions of the standard $\Lambda$CDM model at lower redshifts, where observational constraints are significantly stronger. Our results provide compelling evidence that cosmic strings may play a crucial role in explaining the galaxy properties observed by JWST at high redshifts while maintaining consistency with well-established models at later epochs.

Using sonification on scientific data analysis provides additional dimensions to visualization, potentially increasing researchers' analytical capabilities and fostering inclusion and accessibility. This research explores the potential of multimodal Integral Field Spectroscopy (IFS) applied to galaxy analysis through the development and evaluation of a tool that complements the visualization of datacubes with sound. The proposed application, \textit{ViewCube}, provides interactive visualizations and sonifications of spectral information across a two-dimensional field-of-view, and its architecture is designed to incorporate future sonification approaches. The first sonification implementation described in this article uses a deep learning module to generate binaural unsupervised auditory representations. The work includes a qualitative and quantitative user study based on an online questionnaire, aimed at both specialized and non-specialized participants, focusing on the case study of datacubes of galaxies from the Calar Alto Integral Field Spectroscopy Area (CALIFA) survey. Out of 67 participants who completed the questionnaire, 42 had the opportunity to test the application in person prior to filling out the online survey. 81\% of these 42 participants expressed the good interactive response of the tool, 79.1\% of the complete sample found the application "Useful", and 58.2\% rated its aesthetics as "Good". The quantitative results suggest that all participants were able to retrieve information from the sonifications, pointing to previous experience in the analysis of sound events as more helpful than previous knowledge of the data for the proposed tasks, and highlighting the importance of training and attention to detail for the understanding of complex auditory information.

Recent high redshift ($z>4$) spatially resolved observations with JWST have shown the evolution of star formation rate (SFR) surface density ($\Sigma_{\rm SFR}$) and its main sequence in the $\Sigma_{\rm SFR}$-$M_*$ diagram ($\Sigma_{\rm SFR}$MS) which is already observed at the cosmic morning ($z\sim7.5$). The use of $\Sigma_{\rm SFR}$ is physically motivated due to its normalization by the area where the star formation (SF) occurs, thus indirectly considering the gas density. The $\Sigma_{\rm SFR}$-$M_*$ diagram has been shown to complement widely used (specific)SFR-$M_*$, particularly to select passive galaxies. In this work we aim to establish the $\Sigma_{\rm SFR}$ evolution since $z=12$ in the framework of LGalaxies2020 semi-analytical model (SAM) and to give an interpretation to recent observations. We estimate $\Sigma_{\rm SFR}$(-$M_*$) and cosmic star formation rate density (CSFRD) for the simulated galaxy population and the sub-samples divided in stellar mass bins in the given redshift. The simulated $\Sigma_{\rm SFR}$ decreases by $\sim3.5$ dex from $z=12$ to $z=0$. We show that galaxies with different stellar masses have different paths of $\Sigma_{\rm SFR}$ evolution. %, driven by SFR and effective radius. We find $\Sigma_{\rm SFR}$MS is already observed at $z\sim11$. The simulated $\Sigma_{\rm SFR}$MS agrees with the observed one at $z=0, 1, 2, 5$ and $7.5$ and with individual galaxies at $z>10$. We show that the highest $\Sigma_{\rm SFR}$MS slope of $0.709\pm0.005$ is at $z\sim3$, decreasing to $\sim0.085\pm0.003$ at $z=0$. This is mostly driven by a rapid decrease in SFR with additional size increase of the most massive galaxies in this redshift range. This coincides with the dominance of the most massive galaxies in the CSFRD from the SAM. Observations show the same picture in which $\Sigma_{\rm SFR}$ evolutionary path depends on the stellar mass.

Cluster cosmology can benefit from combining multi-wavelength studies, which can benefit from characterising the correlation coefficients between different mass-observable relations. In this work, we aim to provide information on the scatter, the skewness, and the covariance of various mass-observable relations in galaxy clusters in cosmological hydrodynamic simulations. This information will help future analyses to better tackle accretion histories and projection effects and model mass observable relations for cosmology studies.We identify galaxy clusters in Magneticum Box2b simulations with mass $M_{\rm 200c}>10^{14} {\rm M}_\odot$ at redshift $z=0.24$ and $z=0.90$. Our analysis includes \Euclid-derived properties such as richness, stellar mass, lensing mass, and concentration. Additionally, we investigate complementary multi-wavelength data, including X-ray luminosity, integrated Compton-$y$ parameter, gas mass, and temperature. The impact of projection effects on mass-observable residuals and correlations is then examined. At intermediate redshift ($z=0.24$), projection effects impact lensing concentration, richness, and gas mass the most in terms of scatter and skewness of log-residuals of scaling relations. The contribution of projection effects can be significant enough to boost a spurious hot- vs. cold-baryons correlation and consequently hide underlying correlations due to halo accretion histories. At high redshift ($z=0.9$), the richness has a much lower scatter (of log-residuals), and the quantity that is most impacted by projection effects is the lensing mass. Lensing concentration reconstruction, in particular, is affected by deviations of the reduced-shear profile shape from the one derived by an NFW profile rather than interlopers in the line of sight.

The third r-process peak (Os, Ir, Pt) is poorly understood due to observational challenges, with spectral lines located in the blue or near-ultraviolet region of stellar spectra. These challenges need to be overcome for a better understanding of the r-process in a broader context. To understand how the abundances of the third r-process peak are synthesised and evolve in the Universe, a homogeneous chemical analysis of metal-poor stars using high quality data observed in the blue region of the electromagnetic spectrum (< 400 nm) is necessary. We provide a homogeneous set of abundances for the third r-process peak (Os, Ir, Pt) and Hf, increasing by up to one order of magnitude their availability in the literature. A classical 1D, local thermodynamic equilibrium (LTE) analysis of four elements (Hf, Os, Ir, Pt) is performed, using ATLAS model atmospheres to fit synthetic spectra in high resolution (> 40,000), high signal-to-noise ratio, of 52 red giants observed with UVES/VLT. Due to the heavy line blending involved, a careful determination of upper limits and uncertainties is done. The observational results are compared with state-of-the-art nucleosynthesis models. Our sample displays larger abundances of Ir (Z=77) in comparison to Os (Z=76), which have been measured in a few stars in the past. The results also suggest decoupling between abundances of third r-process peak elements with respect to Eu (rare earth element) in Eu-poor stars. This seems to contradict a co-production scenario of Eu and the third r-process peak elements Os, Ir, and Pt in the progenitors of these objects. Our results are challenging to explain from the nucleosynthetic point of view: the observationally derived abundances indicate the need for an additional early, primary formation channel (or a non-robust r-process).

Bok globules are small, dense clouds that act as isolated precursors for the formation of single or binary stars. Although recent dust polarization surveys, primarily with Planck, have shown that molecular clouds are strongly magnetized, the significance of magnetic fields in Bok globules has largely been limited to individual case studies, lacking a broader statistical understanding. In this work, we introduce a comprehensive optical polarimetric survey of 21 Bok globules. Using Gaia and near-IR photometric data, we produce extinction maps for each target. Using the radiative torque alignment model customized to the physical properties of the Bok globule, we characterize the polarization efficiency of one representative globule as a function of its visual extinction. We thus find our optical polarimetric data to be a good probe of the globule's magnetic field. Our statistical analysis of the orientation of elongated extinction structures relative to the plane-of-sky magnetic field orientations shows they do not align strictly parallel or perpendicular. Instead, the data is best explained by a bimodal distribution, with structures oriented at projected angles that are either parallel or perpendicular. The plane-of-sky magnetic field strengths on the scales probed by optical polarimetric data are measured using the Davis-Chandrasekhar-Fermi technique. We then derive magnetic properties such as Alfv\'en Mach numbers and mass-to-magnetic flux ratios. Our findings statistically place the large-scale (Av < 7 mag) magnetic properties of Bok globules in a dynamically important domain.

Observations of gravitational waves (GWs) from dark sirens allow us to infer their locations and distances. Galaxies, on the other hand, have precise angular positions but no direct measurement of their distances -- only redshifts. The cross-correlation of GWs, which we limit here to binary black hole mergers (BBH), in spherical shells of luminosity distance $D_L$, with galaxies in shells of redshift $z$, leads to a direct measurement of the Hubble diagram $D_L(z)$. Since this standard ruler relies only on the statistical proximity of the dark sirens and galaxies (a general property of large-scale structures), it is essentially model-independent: the correlation is maximal when both redshift and $D_L$ shells coincide. We forecast the constraining power of this technique, which we call {\it{Peak Sirens}}, for run~5~(O5) of LIGO-Virgo-KAGRA (LVK), as well as for the third-generation experiments Einstein Telescope and Cosmic Explorer. We employ thousands of full-sky light cone simulations with realistic numbers for the tracers, and include masking by the Milky Way, lensing and inhomogeneous GW sky coverage. We find that the method is not expected to suffer from some of the issues present in other dark siren methods, such as biased constraints due to incompleteness of galaxy catalogs or dependence on priors for the merger rates of BBH. We show that with Peak Sirens, given the projected O5 sensitivity, LVK can measure $H_0$ with $7\%$ precision by itself, assuming $\Lambda$CDM, and $4\%$ precision using external datasets to constrain $\Omega_m$. We also show that future third-generation GW detectors can achieve, without external data, sub-percent uncertainties in $H_0$ assuming $\Lambda$CDM, and 3\% in a more flexible $w_0w_a$CDM model. The method also shows remarkable robustness against systematic effects such as the modeling of non-linear structure formation.

Context: The clusters Abell 3017 and Abell 3016 are located within a large-scale filament. A prominent X-ray bridge has been detected connecting the two clusters and a potential galaxy group between them. Aims: The aim of this work is to investigate the existence of a radio bridge in the filament between Abell 3017 and Abell 3016, to explore other diffuse radio structures within this system, and to investigate the origins of these diffuse radio emission. Methods: We analyzed MeerKAT L-band data to study the morphology and spectra of the diffuse radio structures in Abell 3016-Abell 3017. X-ray imaging and spectral analysis were carried out with archival Chandra and XMM-Newton data. Additionally, correlations between radio ($I_R$) and X-ray surface brightness ($I_X$) were generated to explore the connections between thermal and non-thermal components in the diffuse radio emission. Results: We detected a faint radio bridge with an average surface brightness of $\sim 0.1~\mu\rm Jy~arcsec^{-2}$ at 1280 MHz using MeerKAT. It connects Abell 3017 with a potential galaxy group and extends towards Abell 3016, aligning with the X-ray bridge. A high X-ray temperature of $7.09 \pm 0.54$ keV detected in the bridge region suggests an interaction between Abell 3017 and the group. In Abell 3017, we identified two distinct components of diffuse radio emission: a radio mini-halo and an outer radio halo with a northern extension (N-extension hereafter). The radio surface brightness profile of Abell 3017 shows a steep inner component consistent with other mini-halos, and a faint outer component likely linked to an infalling subcluster. The $I_{\rm R}-I_{\rm X}$ diagram indicates superlinear and sublinear correlations for the mini-halo and N-extension, respectively.

Physical processes impact galaxy formation and evolution in diverse ways, requiring validation of their implementation in cosmological simulations through comparisons with real data across various galaxy types and properties. In this second paper of the CASCO series, we compare the structural properties and dark matter (DM) content of early-type galaxies from the CAMELS IllustrisTNG simulations to three observational datasets (SPIDER, $\textrm{ATLAS}^{\textrm{3D}}$, and MaNGA DynPop), to constrain cosmological and astrophysical feedback parameters, contrasting these results with those obtained for late-type galaxies. We analyze the size-, internal DM fraction-, and DM mass-stellar mass relations, identifying the best-fit simulation for each dataset. For SPIDER, we find cosmological parameter values consistent with literature and results obtained from the comparison between simulations and late-type galaxies, with supernova feedback parameters differing from results derived for late-type galaxies. For $\textrm{ATLAS}^{\textrm{3D}}$, cosmological parameter results align with SPIDER, while supernova feedback parameters are more consistent with late-type galaxies results. MaNGA DynPop yields extreme cosmological parameter values but similar supernova feedback results to $\textrm{ATLAS}^{\textrm{3D}}$. However, no single simulation matches the full range of observational trends, especially when combining early- and late-type galaxies from MaNGA DynPop. These findings highlight the limitations of simulations in reproducing diverse galaxy properties, underscoring the challenge of capturing the complexity of galaxy formation across all types.

We present a mathematical analysis of the spectro-temporal properties of Fast Radio Bursts (FRBs), focusing on the distortions introduced by propagation effects such as scattering and inaccurate de-dispersion. By examining the impact of different scattering timescales and residual dispersion measures (DMs), both independently and in combination, we identify systematic trends in the sub-burst slope law as defined within the framework of the Triggered Relativistic Dynamical Model (TRDM). These effects primarily alter the measurements of the sub-burst slope and duration, thereby also modifying their correlations with other properties, such as central frequency and bandwidth. Our results show that scatter-induced temporal broadening affects duration more than slope, with weak to moderate scattering subtly modifying the sub-burst slope law and strong scattering causing significant deviations. Residual dispersion preferentially modifies the slope, further changing the trends predicted by the sub-burst slope law. Ultra-short bursts (or ultra-FRBs) emerge as particularly susceptible to these effects even at relatively high frequencies, underscoring the need for precise treatment of scattering and accurate dedispersion before performing analyses. Our findings emphasize the necessity for higher frequency observations (especially for ultra-FRBs) to improve the DM estimates as well as the measurements of spectro-temporal properties.

KT Eri is a classical nova which went into outburst in 2009. Recent photometric analysis in quiescence indicates a relatively longer orbital period of 2.6 days, so that KT Eri could host a very bright accretion disk during the outburst like in the recurrent nova U Sco, the orbital period of which is 1.23 days. We reproduced the optical $V$ light curve as well as the supersoft X-ray light curve of KT Eri in outburst, assuming a large irradiated disk during a nova wind phase of the outburst while a normal size disk after the nova winds stop. This result is consistent with the temporal variation of wide-band $V$ brightness that varies almost with the intermediate-band Str\"omgren $y$ brightness, because the $V$ flux is dominated by continuum radiation, the origin of which is a photospheric emission from the very bright disk. We obtained the white dwarf mass to be $M_{\rm WD}= 1.3\pm0.02 ~M_\odot$, the hydrogen-burning turnoff epoch to be $\sim 240$ days after the outburst, the distance modulus in the $V$ band to be $(m-M)_V=13.4\pm 0.2$, and the distance to KT Eri to be $d=4.2\pm0.4$ kpc for the reddening of $E(B-V)= 0.08$. The peak absolute $V$ brightness is about $M_{V, \rm max}= -8.0$ and the corresponding recurrence time is $\sim 3,000$ yr from its ignition mass together with the mean mass-accretion rate of $\dot{M}_{\rm acc}\sim 1\times 10^{-9} ~M_\odot$ yr$^{-1}$ in quiescence. Thus, we suggest that KT Eri is not a recurrent nova.

We compute the linearised dispersion relations of shear waves, heat waves, and sound waves in relativistic ''matter+radiation'' fluids with grey absorption opacities. This is done by solving radiation hydrodynamics perturbatively in the ratio ''radiation stress-energy''/''matter stress-energy''. The resulting expressions $\omega \, {=} \, \omega(k)$ accurately describe the hydrodynamic evolution for any $k\, {\in}\, \mathbb{R}$. General features of the dynamics (e.g., covariant stability, propagation speeds, and damping of discontinuities) are argued directly from the analytic form of these dispersion relations.

Planck observed the whole sky between 350um and 3mm, discovering thousands of unresolved peaks in the cosmic infrared background. The nature of these peaks are still poorly understood - while some are strong gravitational lenses, the majority are spatial overdensities of star-forming galaxies, but with almost no redshift constraints. PLCK G073.4-57.5 (G073) is one of these Planck-selected peaks. G073 was previously observed by ALMA, with the results suggesting the presence of two structures (one around redshift 1.5 and one around redshift 2) aligned along the line of sight, but the results lacked robust spectroscopic confirmation. Characterizing the full redshift distribution of the galaxies within G073 is needed in order to better understand this representative example of these objects, and connect them to the emergence of galaxy clusters. We use ALMA spectral scans to search for CO and CI(1-0) line emission, targeting eight red Herschel-SPIRE sources in the field and four bright SCUBA-2 sources. We find 15 emission lines in 13 galaxies, and we secure the spectroscopic redshifts of all 13 galaxies. 11 of these galaxies are SPIRE-selected and lie in two structures at z=1.53 and z=2.31, while the two SCUBA-2-selected galaxies are at z=2.61. Using multiwavelength photometry we constrain stellar masses and star-formation rates, and using the CO and CI emission lines we constrain gas masses. Our protocluster galaxies exhibit typical depletion timescales compared to field galaxies at the same redshifts, but enhanced gas-to-stellar mass ratios, potentially driven by emission line selection effects. We find that the two structures confirmed in our survey are reproduced in cosmological simulations of star-forming halos at high redshift; the simulated halos have a 60-70% probability of collapsing into galaxy clusters, implying that the two structures in G073 are genuinely protoclusters.

Grain growth in disks around young stars plays a crucial role in the formation of planets. Early grain growth has been suggested in the HH 212 protostellar disk by previous polarization observations. To confirm it and to determine the grain size, we analyze high-resolution multi-band observations of the disk obtained with Atacama Large Millimeter/submillimeter Array (ALMA) in Bands 9 (0.4 mm), 7 (0.9 mm), 6 (1.3 mm), 3 (3 mm) as well as with Very Large Array (VLA) in Band Ka (9 mm) and present new VLA data in Bands Q (7 mm), K (1.3 cm), and X (3 cm). We adopt a parameterized flared disk model to fit the continuum maps of the disk in these bands and derive the opacities, albedos, and opacity spectral index $\mathrm{\beta}$ of the dust in the disk, taking into account the dust scattering ignored in the previous work modeling the multi-band data of this source. For the VLA bands, since the continuum emission of the disk is more contaminated by the free-free emission at longer wavelengths, we only include the Band Q data in our modeling. The obtained opacities, albedos, and opacity spectral index $\beta$ (with a value of $\sim$ 1.2) suggest that the upper limit of maximum grain size in the disk be $\sim$ 130 $\mu$m, consistent with that implied in the previous polarization observations in Band 7, supporting the grain growth in this disk.

In this paper, through analysis, modelings, and simulations, we show that if the spectra of fast radio bursts (FRBs) are intrinsically quasi-periodic spectra, likely produced by coherent curvature radiation from quasi-periodic structured bunches, then the observed steep and shallow spectra, narrow and broadband spectra, multi-frequency simultaneous spectra, as well as possible statistical fringe spectra in FRBs, could all be various manifestations of these intrinsically quasi-periodic spectra. If so, the period properties of the structured bunches, as inferred from the observed multi-frequency simultaneous spectra and potential statistical fringe spectra, may provide valuable insights into the mechanisms behind the formation of such structured bunches.

We performed photometric and spectroscopic studies of three large amplitude contact binaries, NSVS 2418361, ATLAS J057.1170+31.2384 and NSVS 7377875. The amplitudes of three systems' light curves are more than 0.7 magnitude. We analyzed the light curves using Wilson-Devinney code to yield physical parameters. The photometric solutions suggested that NSVS 7377875 belongs to an A-subtype contact binary, while the others are classified as W-subtype ones. Furthermore, the mass ratio of NSVS 7377875 is higher than 0.72, so it belongs to H-subtype contact binaries. Since their light curves have unequal height at two maxima which is called O'Connell effect, a dark spot on the primary component for each target was required to get a better fit of light curves. The orbital period investigation shows that the period of NSVS 2418361 is increasing, indicating a mass transfer from the less massive component to the more massive one, while the other targets exhibit no long-term variation. Our spectral subtraction analysis of LAMOST spectra revealed excess emissions in the $H_\alpha$ line, indicating chromospheric activity in all the three targets. The Gaia distance was applied to estimate the absolute parameters of the three targets, and we obtained their evolutionary state. The relationships between the energy transfer parameter of 76 H-subtype contact binaries and their bolometric luminosity ratios, as well as their contact degree, were presented. We discovered that H-subtype systems have less efficient energy transfer rate, which is corresponding to the conclusion proposed by Csizmadia \& Klagyivik.

X-ray reflection spectroscopy is a powerful tool to study the strong gravity region of black holes. The next generation of astrophysical X-ray missions promises to provide unprecedented high-quality data, which could permit us to get very precise measurements of the properties of the accretion flow and of the spacetime geometry in the strong gravity region around these objects. In this work, we test the accuracy of the relativistic calculations of the reflection model relxill and of its extension to non-Kerr spacetimes relxill_nk in view of the next generation of X-ray missions. We simulate simultaneous observations with Athena/X-IFU and LAD of bright Galactic black holes with a precise and accurate ray-tracing code and we fit the simulated data with the latest versions of relline and relline_nk. While we always recover the correct input parameters, we find residuals in the fits when the emission from the inner part of the accretion disk is higher. Such residuals disappear if we increase the number of interpolation points on the disk in the integral of the transfer function. We also simulate full reflection spectra and find that the emission angle from the accretion disk should be treated properly in this case.

Strong lensing directly probes the internal structure of the lensing galaxies. In this paper, we investigate the relation between the internal structure of massive elliptical galaxies and their environment using a sample of 15 strong lensing systems. We performed lens modeling for them using Lenstronomy and constrained the mass and light distributions of the deflector galaxies. We adopt the local galaxy density as a metric for the environment and test our results against several alternative definitions of it. We robustly find that the centroid offset between the mass and light is not correlated with the local galaxy density. This result supports using centroid offsets as a probe of dark matter theories since the environment's impact on it can be treated as negligible. Although we find a strong correlation between the position angle offset and the standard definition of the local galaxy density, consistent with previous studies, the correlation becomes weaker for alternative definitions of the local galaxy density. This result weakens the support for interpreting the position angle misalignment as having originated from interaction with the environment. Furthermore, we find the 'residual shear' magnitude in the lens model to be uncorrelated with the local galaxy density, supporting the interpretation of the residual shear originating, in part, from the inadequacy in modeling the angular structure of the lensing galaxy and not solely from the structures present in the environment or along the line of sight.

The two-state solar wind paradigm is based on observations showing that slow and fast solar wind have distinct properties like helium abundances, kinetic signatures, elemental composition, and charge-state ratios. Nominally, the fast wind originates from solar sources that are continuously magnetically open to the heliosphere like coronal holes while the slow wind is from solar sources that are only intermittently open to the heliosphere like helmet streamers and pseudostreamers. The Alfv\'enic slow wind is an emerging 3rd class of solar wind that challenges the two-state fast/slow paradigm. It has slow wind speeds but is highly Alfv\'enic, i.e. has a high correlation between velocity and magnetic field fluctuations along with low compressibility typical of Alfv\'en waves, which is typically observed in fast wind. Its other properties are also more similar to the fast than slow wind. From 28 years of Wind observations at 1 AU, we derive the solar wind helium abundance ($A_\mathrm{He}$), Alfv\'enicity ($\left|\sigma_c\right|$), and solar wind speed ($v_\mathrm{sw}$). Characterizing vsw as a function of $\left|\sigma_c\right|$ and $A_\mathrm{He}$, we show that the maximum solar wind speed for plasma accelerated in source regions that are intermittently open is faster than the minimum solar wind speed for plasma accelerated in continuously open regions. We infer that the Alfv\'enic slow wind is likely solar wind originating from open-field regions with speeds below the maximum solar wind speed for plasma from intermittently open regions. We then discuss possible implications for solar wind heating and acceleration. Finally, we utilize the combination of helium abundance and normalized cross helicity to present a novel solar wind categorization scheme.

Eclipsing binaries (EBs) play an important astrophysical role in studying stellar properties and evolution. By analyzing photometric data in the LAMOST Medium-Resolution Survey field, RA: $23^h$$01^m$$51.00^s$, Dec: +34$^\circ$36$^\prime$45$^{\prime \prime}$, 48 EBs are detected and 2 are newly discovered. This specific field has been observed 52 times by the LAMOST Medium-Resolution Survey DR 9, which facilitates a comprehensive analysis of the EBs. For EBs with LAMOST medium-resolution spectra, radial velocity curves were obtained, and their precise orbital parameters were determined by simultaneously analyzing photometric light curves and radial velocity curves. For the other EBs with only photometric light curves, we used the q-search or the temperature ratio method to determine their initial mass ratios and then determined the orbital parameters. It is found that 15 EBs belong to detached systems, 1 to semi-detached systems, and 32 to contact systems. Based on the O-C analysis for 26 EBs with sufficient eclipsing times, we found a long-term decrease in the orbital period of 11 EBs and a continuous increase of 5 EBs, which are due to the material transfer between the two components. The O-C curve of 1 EB shows a distinct periodic variation, which is caused by the light travel time effect, and the third body is likely to be a black hole. By applying the spectral subtraction method to 13 EBs with LAMOST medium-resolution spectra, 10 systems exhibit distinct H$\alpha$ emission lines, in which 1 system exhibits double-peaked lines near phases 0.25 and 0.75, implying strong chromospheric activity. In the mass-luminosities and mass-radius distributions, most of the more massive components are less evolved than the less massive ones.

Identifying Galactic PeVatrons (PeV particle accelerators) from the ultra-high-energy (UHE, >100 TeV) $\gamma$-ray sources plays a crucial role in revealing the origin of Galactic cosmic rays. The UHE source 1LHAASO J1857+0203u is suggested to be associated with HESS J1858+020, which may be attributed to the possible PeVatron candidate supernova remnant (SNR) G35.6$-$0.4 or HII region G35.6$-$0.5. We perform detailed analysis on the very-high-energy and UHE $\gamma$-ray emissions towards this region with data from the Large High Altitude Air Shower Observatory (LHAASO). 1LHAASO J1857+0203u is detected with a significance of 11.6$\sigma$ above 100 TeV, indicating the presence of a PeVatron. It has an extension of $\sim 0.18^\circ$ with a power-law (PL) spectral index of $\sim$2.5 in 1-25 TeV and a point-like emission with a PL spectral index of $\sim$3.2 above 25 TeV. Using the archival CO and HI data, we identify some molecular and atomic clouds that may be associated with the TeV $\gamma$-ray emissions. Our modelling indicates that the TeV $\gamma$-ray emissions are unlikely to arise from the clouds illuminated by the protons that escaped from SNR G35.6$-$0.4. In the scenario that HII region G35.6$-$0.5 could accelerate particles to the UHE band, the observed GeV-TeV $\gamma$-ray emission could be well explained by a hadronic model with a PL spectral index of $\sim$2.0 and cutoff energy of $\sim$450 TeV. However, an evolved pulsar wind nebula origin cannot be ruled out.

Multi-agent systems (MAS) utilizing multiple Large Language Model (LLM) agents with Retrieval Augmented Generation (RAG) can execute code locally and may become beneficial in cosmological data analysis. Here, we illustrate a first small step towards AI-assisted analyses and a glimpse of the potential of MAS to automate and optimize scientific workflows. The system architecture of our example package, that builds upon the autogen/ag2 framework, can be applied to MAS in any area of quantitative scientific research. Our work-in-progress code is open source and available at https://github.com/CMBAgents/cmbagent.

In our galaxy, white dwarfs inevitably undergo scattering and capture processes with the interstellar diffuse dark matter. The captured dark matter forms a dark halo that eventually evaporates or annihilates. Theoretical pulsation modes and observations of pulsating white dwarfs provide predictions about their evolution. This motivates us to study the impact of sub-MeV interstellar dark matter on the cooling processes of white dwarfs. In this work, we consider the collisions between dark matter and relativistic degenerate electrons inside white dwarfs, numerically calculating the energy input and output results from scattering, capture, evaporation, and annihilation processes. Based on observational data from G117-B15, we conclude that the maximum cooling luminosity of the interstellar sub-MeV dark matter is approximately $10^{22} \, \text{erg}/\text{s}$, which is insufficient to provide an effective cooling mechanism for white dwarfs. Finally, if future observations detect a pulsating white dwarf in the Galactic center, the potential sensitivity of this scenario could extend to the region$10^{-3}\,\text{MeV} < m_\chi < 10 \, \text{MeV}$ and $6.02 \times 10^{-38}\,\text{cm}^2 > \sigma_0 \geq 1.5 \times 10^{40} \, \text{cm}^2$.

This paper leverages the first released catalog from the FAST All Sky \textsc{Hi} Survey (FASHI) to examine the hypothesis of cosmic isotropy in the local Universe. Given the design of the overall FAST survey, the inhomogeneous detection sensitivity of FASHI is likely to introduce significant biases in the statistical properties of the catalog. To mitigate the potential influence of spurious clustering effects due to these sensitivity variations, we focus on extragalactic \textsc{Hi} sources within the sensitivity range of $[0.65, 1.0]$. This refined subsample is divided into ten distinct sky regions, for which we compute the two-point angular correlation functions (2PACF) over angular scales of $0.5^\circ < \theta < 10^\circ$. We apply the Markov chain Monte Carlo method to fit these 2PACFs with a power-law model and assess the statistical significance of the best-fit parameters for the ten FASHI sky regions by comparing them against results from mock catalogs generated under the assumptions of homogeneity and isotropy. Our findings indicate that the local Universe, as traced by the \textsc{Hi} sources in the FASHI survey, aligns with the cosmic isotropy hypothesis within a $2\sigma$ confidence level. We do not detect any statistically significant deviations from cosmic isotropy in the FASHI survey data.

Light volatile elements in lunar regolith are thought to be a mixture of the solar wind and Earth's atmosphere, the latter sourced in the absence of geomagnetic field. However, the extent to which both the current and primitive geodynamo influence the transport of terrestrial ions still remains unclear, and this uncertainty is further complicated by the enigmatic composition and poorly constrained location of the Eoarchean exosphere. Here we use 3-D MHD numerical simulations with present-day magnetized and Archean unmagnetized atmospheres to investigate how Earth's intrinsic magnetic field affects this transfer, aiming to constrain how and when the lunar isotopic signature provides a record of Earth's paleoatmosphere. We find that atmospheric transfer is efficient only when the Moon is within Earth's magnetotail. The non-solar contribution to the lunar soil is best explained by implantation during the long history of the geodynamo, rather than any short, putatively unmagnetized epoch of early Earth. This further suggests the history of the terrestrial atmosphere, spanning billions of years, could be preserved in buried lunar soils. Our results indicate that the elemental abundances of Apollo samples are very sensitive to Earth's exobase altitude, which, at the time of ion implantation, was never smaller than 190 km.

Many young clusters possess extended main sequences, a phenomenon commonly ascribed to stellar rotation. However, the mechanism behind their very wide stellar rotation distributions remains unclear. A proposed explanation is that magnetic star-disk interaction can regulate stellar rotation, i.e., protostars with longer disk lifetimes will eventually evolve into slow rotators, and vice versa. To examine this hypothesis, we took the star forming region, NGC 2264, as a test bed. We have studied its high-mass pre-main-sequence and zero-age main-sequence stars. We found that on average, disk-less pre-main-sequence stars rotate faster than their disk-bearing counterparts. The stellar rotation distribution of its zero-age main-sequence stars is similar to evolved young clusters. We conclude that disk-locking may play a crucial role in the rotational velocity distribution of intermediate-mass early-type stars. We suggest that the observed wide stellar rotation distribution in many young clusters can occur in their early stages.

Particles are accelerated to very high, non-thermal energies in space, solar, and astrophysical plasma environments. In cosmic ray physics, the "Hillas limit" is often used as a rough estimate (or the necessary condition) of the maximum energy of particles. This limit is based on the concepts of one-shot direct acceleration by a system-wide motional electric field, as well as stochastic and diffusive acceleration in strongly turbulent environments. However, it remains unclear how well this limit explains the actual observed maximum energies of particles. Here we show, based on a systematic review, that the observed maximum energy of particles -- those in space, solar, astrophysical, and laboratory environments -- often reach the energy predicted by the Hillas limit. We also found several exceptions, such as electrons in solar flares and jet-terminal lobes of radio galaxies, as well as protons in planetary radiation belts, where deviations from this limit occur. We discuss possible causes of such deviations, and we argue in particular that there is a good chance of detecting ultra-high-energy ($\sim$100 GeV) solar flare electrons that have not yet been detected. We anticipate that this study will facilitate further interdisciplinary discussions on the maximum energy of particles and the underlying mechanisms of particle acceleration in diverse plasma environments.

We present the results of a novel type of numerical simulation that realizes a rotating Universe with a shear-free, rigid body rotation inspired by a G\"{o}del-like metric. We run cosmological simulations of unperturbed glasses with various degrees of rotation in the Einstein-de Sitter and the $\Lambda$CDM cosmologies. To achieve this, we use the StePS N-body code capable of simulating the infinite Universe, overcoming the technical obstacles of classical toroidal (periodic) topologies that would otherwise prevent us from running such simulations. Results show a clear anisotropy between the polar and equatorial expansion rates with more than $1\%$ deviation from the isotropic case for maximal rotation without closed timeline curves within the horizon, $\omega_{0} \approx 10^{-3}$ Gyr$^{-1}$; a considerable effect in the era of precision cosmology.

We present a systematic analysis of the spatially resolved star formation histories (SFHs) using Hubble Space Telescope imaging data of $\sim 997$, intermediate redshifts $0.5 \leq z \leq 2.0$ galaxies from the GOODS-S field, with stellar mass range $9.8 \leq \log \mathrm{M}_{\star}/\mathrm{M}_{\odot} \leq 11.5$. We estimate the SFHs in three spatial regions (central region within the half-mass radii $\mathrm{R}_{50s}$, outskirts between $1-3~\mathrm{R}_{50s}$, and the whole galaxy) using pixel-by-pixel spectral-energy distribution (SED) fitting, assuming exponentially declining tau model in individual pixels. The reconstructed SFHs are then used to derive and compare the physical properties such as specific star-formation rates (sSFRs), mass-weighted ages (t$_{\mathrm{50}}$), and the half-mass radii to get insights on the interplay between the structure and star-formation in galaxies. The correlation of sSFR ratio of the center and outskirts with the distance from the main sequence (MS) indicates that galaxies on the upper envelope of the MS tend to grow outside-in, building up their central regions, while those below the MS grow inside-out, with more active star formation in the outskirts. The findings suggest a self-regulating process in galaxy size growth when they evolve along the MS. Our observations are consistent with galaxies growing their inner bulge and outer disc regions, where they appear to oscillate about the average MS in cycles of central gas compaction, which leads to bulge growth, and subsequent central depletion possibly due to feedback from the starburst, resulting in more star formation towards the outskirts from newly accreted gas.

We characterize magnetic fields produced during electroweak symmetry breaking by non-dynamical numerical simulations based on the Kibble mechanism. The generated magnetic fields were thought to have an energy spectrum $\propto k^3$ for small wavenumbers $k$, but here we show that it is actually a spectrum $\propto k^4$ along with characteristic fluctuations in the magnetic helicity. Using scaling results from MHD simulations for the evolution and assuming that the initial magnetic field is coherent on the electroweak Hubble scale, we estimate the magnetic field strength to be $\sim 10^{-13}\, {\rm G}$ on kpc scales at the present epoch for non-helical fields. For maximally helical fields we obtain $\sim 10^{-10}\, {\rm G}$ on Mpc scales. We also give scalings of these estimates for partially helical fields.

We complement the $y$-band template light curves for RR Lyrae to the well-established template light curves in the $ugriz$-band, where the latter have been adopted in the astroML/gatspy python package as one of the period-search methods for RR Lyrae. These $y$-band template light curves were constructed based on the $z$-band time series data taken from the Sloan Digital Sky Survey (SDSS), the $y$-band light curves from the Pan-STARRS1 survey, and dedicated $y$-band observations using the Lulin One-meter Telescope for RR Lyrae located in the SDSS Stripe 82 region. These $y$-band template light curves, 9 for the ab-type RR Lyrae and 3 for the c-type RR Lyrae, can be applied in conjunction to the $ugriz$-band template light curves for upcoming sky surveys involving the $y$-band, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST).

Sagittarius A East is a supernova remnant with a unique surrounding environment, as it is located in the immediate vicinity of the supermassive black hole at the Galactic center, Sagittarius A*. The X-ray emission of the remnant is suspected to show features of overionized plasma, which would require peculiar evolutionary paths. We report on the first observation of Sagittarius A East with X-Ray Imaging and Spectroscopy Mission (XRISM). Equipped with a combination of high-resolution microcalorimeter spectrometer and large field-of-view CCD imager, we for the first time resolved the Fe XXV K-shell lines into fine structure lines and measured the forbidden-to-resonance intensity ratio to be 1.39+/-0.12, which strongly suggests the presence of overionized plasma. We obtained a reliable constraint on the ionization temperature just before the transition into the overionization state, to be > 4 keV. The recombination timescale was constrained to be < 8e11 cm-3 s. The small velocity dispersion of 109+/-6 km s-1 indicates a low Fe ion temperature < 8 keV and a small expansion velocity < 200 km s-1. The high initial ionization temperature and small recombination timescale suggest that either rapid cooling of the plasma via adiabatic expansion from dense circumstellar material or intense photoionization by Sagittarius A* in the past may have triggered the overionization.

We present an analysis of the structure, kinematics, and chemo-dynamical properties of the Milky Way bulge using data from OGLE, APOGEE, and Gaia. Firstly, we identified 2,156 ab-type RR Lyrae stars (RRabs) from OGLE-IV, then through their apocenters derived from orbital integration, we distinguished three populations: the central bulge RRabs, the inner bulge RRabs and halo interlopers. Inner bulge RRabs kinematically align with the Galactic bar, while central bulge RRabs show slower rotation with lower velocity dispersion, which do not trace the bar. Higher velocity dispersion stars were identified as halo interlopers. Then, orbital analysis of 28,188 APOGEE Red Clump and Red Giant Branch stars revealed kinematic properties consistent with RRabs, and chemical abundance distribution displayed a bimodal stellar density pattern, suggesting complex star evolution histories and also slightly different star formation histories for the inner bulge and central bulge. The differences in the density distribution on the $|\mathrm{Z}|_{\text{max}}$-eccentricity plane for the central bulge, inner bulge, and halo regions are clearly detected. Finally, the chemodynamical analysis of 301,485 Gaia DR3 red giants without orbital integration indicated that metal-rich bulge stars form a bar-like structure, while metal-poor bulge stars are dominated by velocity dispersion. It is found that the classification of bulge stars based on orbital parameters, rather than solely on metallicity, provides a more accurate population separation. Our results also support that secular evolution of the Galactic disk is the primary origin of the bulge, and boxy/peanut (B-P) bulge population might be more dominant than X-shape bulge population.

We present a novel dataset of simulations of the photodissociation region (PDR) in the Orion Bar and provide benchmarks of emulators for the dataset. Numerical models of PDRs are computationally expensive since the modeling of these changing regions requires resolving the thermal balance and chemical composition along a line-of-sight into an interstellar cloud. This often makes it a bottleneck for 3D simulations of these regions. In this work, we provide a dataset of 8192 models with different initial conditions simulated with 3D-PDR. We then benchmark different architectures, focusing on Augmented Neural Ordinary Differential Equation (ANODE) based models (Code be found at https://github.com/uclchem/neuralpdr). Obtaining fast and robust emulators that can be included as preconditioners of classical codes or full emulators into 3D simulations of PDRs.

We conducted an extensive study of the spheroidal dwarf satellite galaxies around the Andromeda galaxy to produce an extensive catalog of LPV stars. The optical monitoring project consists of 55 dwarf galaxies and four globular clusters that are members of the Local Group. We have made observations of these galaxies using the WFC mounted on the 2.5 m INT in nine different periods, both in the i-band filter Sloan and in the filter V-band Harris. We aim to select AGB stars with brightness variations larger than 0.2 mag to investigate the evolutionary processes in these dwarf galaxies. The resulting catalog of LPV stars in Andromeda's satellite galaxies offers updated information on features like half-light radii, TRGB magnitudes, and distance moduli. This manuscript will review the results obtained for And II galaxy. Using the Sobel filter, we have calculated the distance modulus for this satellite galaxy, which ranges from 23.90 to 24.11 mag.

The Lyman alpha (Lya) forest in the spectra of z>5 quasars provides a powerful probe of the late stages of the Epoch of Reionization (EoR). With the recent advent of exquisite datasets such as XQR-30, many models have struggled to reproduce the observed large-scale fluctuations in the Lya opacity. Here we introduce a Bayesian analysis framework that forward-models large-scale lightcones of IGM properties, and accounts for unresolved sub-structure in the Lya opacity by calibrating to higher-resolution hydrodynamic simulations. Our models directly connect physically-intuitive galaxy properties with the corresponding IGM evolution, without having to tune "effective" parameters or calibrate out the mean transmission. The forest data, in combination with UV luminosity functions and the CMB optical depth, are able to constrain global IGM properties at percent level precision in our fiducial model. Unlike many other works, we recover the forest observations without evoking a rapid drop in the ionizing emissivity from z~7 to 5.5, which we attribute to our sub-grid model for recombinations. In this fiducial model, reionization ends at $z=5.44\pm0.02$ and the EoR mid-point is at $z=7.7\pm0.1$. The ionizing escape fraction increases towards faint galaxies, showing a mild redshift evolution at fixed UV magnitude, Muv. Half of the ionizing photons are provided by galaxies fainter than Muv~-12, well below direct detection limits of optical/NIR instruments including JWST. We also show results from an alternative galaxy model that does not allow for a redshift evolution in the ionizing escape fraction. Despite being decisively disfavored by the Bayesian evidence, the posterior of this model is in qualitative agreement with that from our fiducial model. We caution however that our conclusions regarding the early stages of the EoR and which sources reionized the Universe are more model-dependent.

The compression of multi-frequency cosmic microwave background (CMB) power spectrum measurements into a series of foreground-marginalised CMB-only band powers allows for the construction of faster and more easily interpretable 'lite' likelihoods. However, obtaining the compressed data vector is computationally expensive and yields a covariance matrix with sampling noise. In this work, we present an implementation of the CMB-lite framework relying on automatic differentiation. The technique presented reduces the computational cost of the lite likelihood construction to one minimisation and one Hessian evaluation, which run on a personal computer in about a minute. We demonstrate the efficiency and accuracy of this procedure by applying it to the differentiable SPT-3G 2018 TT/TE/EE likelihood from the candl library. We find good agreement between the marginalised posteriors of cosmological parameters yielded by the resulting lite likelihood and the reference multi-frequency version for all cosmological models tested; the best-fit values shift by $<0.1\,\sigma$, where $\sigma$ is the width of the multi-frequency posterior, and the inferred parameter error bars match to within $<10\%$. We publicly release the SPT-3G 2018 TT/TE/EE lite likelihood and a python notebook showing its construction at https://github.com/Lbalkenhol/candl .

In \citep{Qin+}, we attempted to reconstruct the weak lensing convergence map $\hat{\kappa}$ from cosmic magnification by linearly weighting the DECaLS galaxy overdensities in different magnitude bins of $grz$ photometry bands. The $\hat{\kappa}$ map is correlated with cosmic shear at 20-$\sigma$ significance. However, the low galaxy number density in the DECaLS survey prohibits the measurement of $\hat{\kappa}$ auto-correlation. In this paper, we apply the reconstruction method to the Dark Energy Survey Year 3 (DES Y3) galaxies from the DES Data Release 2 (DR2). With greater survey depth and higher galaxy number density, convergence-shear cross-correlation signals are detected with $S/N\approx 9,16,20$ at $0.4

It is yet to be understood how large-scale environments influence star formation activity in galaxy clusters. One recently proposed mechanism is that galaxy clusters can remain star-forming when fed by infalling groups and star-forming galaxies from large-scale structures surrounding them (the \textit{``web-feeding model"}). Using the COSMOS2020 catalog that has half a million galaxies with high accuracy ($\sigma_{\Delta z /1+z} \sim 0.01$) photometric redshifts, we study the relationship between star formation activities in galaxy clusters and their surrounding environment to test the web-feeding model. We first identify $68$ cluster candidates at $0.3 \leq z \leq 1.4$ with halo masses at $10^{13.0} - 10^{14.5}$ \SI{}{M_{\odot}}, and the surrounding large-scale structures (LSSs) with the friends-of-friends algorithm. We find that clusters with low fractions of quiescent galaxies tend to be connected with extended LSSs as expected in the web-feeding model. We also investigated the time evolution of the web-feeding trend using the IllustrisTNG cosmological simulation. Even though no clear correlation between the quiescent galaxy fraction of galaxy clusters and the significance of LSSs around them is found in the simulation, we verify that the quiescent galaxy fractions of infallers such as groups ($M_{200} \geq 10^{12}$ \SI{}{M_{\odot}}) and galaxies ($M_{200} < 10^{12}$ \SI{}{M_{\odot}}) is smaller than the quiescent fraction of cluster members and that infallers can lower the quiescent fraction of clusters. These results imply that cluster-to-cluster variations of quiescent galaxy fraction at $z \leq 1$ can at least partially be explained by feeding materials through cosmic webs to clusters.

Until about a decade ago, ring systems were only known to exist around giant planets. Each one of the four giant planets harbours its own distinctive and unique system of rings and inner satellites. The past decade has been marked by the unexpected discoveries of dense rings around small objects of the outer solar system: the Centaur object Chariklo (and possibly Chiron), the dwarf planet Haumea and the trans-Neptunian object Quaoar. In the latter case, an additional surprise came from the fact that Quaoar's rings orbit well beyond the Roche limit of the body. Here, we address the possible origins and evolution of these ring systems.

Symbiotic stars are binaries in which a cool and evolved star of luminosity class I-III accretes onto a smaller companion. However, direct accretion signatures like disc flickering and boundary layer X-rays are typically outshone or suppressed by the luminous giant, shell burning on the accreting white dwarf, and the illuminated wind nebula. We present a new way to find symbiotics that is less biased against directly-detectable accretion discs than methods based on narrow-band H$\alpha$ photometry or objective prism plate surveys. We identified outliers in SkyMapper survey photometry, using reconstructed uvg snapshot colours and rapid variability among the three exposures of each 20-minute SkyMapper Main Survey filter sequence, from a sample of 366,721 luminous red objects. We found that SkyMapper catalog colours of large-amplitude pulsating giants must be corrected for variability, and that flickering is detectable with only three data points. Our methods probed a different region of parameter space than a recent search for accreting-only symbiotics in the GALAH survey, while being surprisingly concordant with another survey's infrared detection algorithm. We discovered 12 new symbiotics, including four with optical accretion disc flickering. Two of the optical flickerers exhibited boundary-layer hard X-rays. We also identified 10 symbiotic candidates, and discovered likely optical flickering in the known symbiotic V1044 Cen (CD-36 8436). We conclude that at least 20% of the true population of symbiotics exhibit detectable optical flickering from the inner accretion disc, the majority of which do not meet the H$\alpha$ detection thresholds used to find symbiotics in typical narrow-band surveys.

A weakly magnetized neutron star (NS) undergoing disk accretion should release about a half of its power in a compact region known as the accretion boundary layer. Latitudinal spread of the accreted matter and efficient radiative cooling justify the approach to this flow as a two-dimensional spreading layer (SL) on the surface of the star. Numerical simulations of SLs are challenging because of the curved geometry and supersonic nature of the problem. We develop a new two-dimensional hydrodynamics code that uses the multislope second-order MUSCL scheme in combination with an HLLC+ Riemann solver on an arbitrary irregular mesh on a spherical surface. The code is suitable and accurate for Mach numbers at least up to 5-10. Adding sinks and sources to the conserved variables, we simulate constant-rate accretion onto a spherical NS. During the early stages of accretion, heating in the equatorial region triggers convective instability that causes rapid mixing in latitudinal direction. One of the outcomes of the instability is the development of a two-armed `tennis ball' pattern rotating as a rigid body. From the point of view of a high-inclination observer, its contribution to the light curve is seen as a high-quality-factor quasi-periodic oscillation mode with a frequency considerably smaller than the rotation frequency of the matter in the SL. Other variability modes seen in the simulated light curves are probably associated with low-azimuthal-number Rossby waves.

Molecular clouds fragment under the action of supersonic turbulence & gravity which results in a scale-free hierarchical distribution of star formation (SF) within galaxies. Recent studies suggest that the hierarchical distribution of SF in nearby galaxies shows a dependence on host galaxy properties. In this context, we study the nature of hierarchical SF from a few tens of pc up to several kpc in 4 nearby spiral galaxies NGC1566, NGC5194, NGC5457 & NGC7793, by leveraging the large FoV & high resolution FUV+NUV observations from the UltraViolet Imaging Telescope (UVIT). Using the two-point correlation function, we infer that the young star-forming clumps (SFCs) in the galaxies are arranged in a fractal-like hierarchical distribution, but only up to a maximum scale ($l_{corr}$) & it ranges from 0.5 kpc to 3.1 kpc. The flocculent spiral NGC7793 has $\sim$5 times smaller $l_{corr}$ than the 3 grand design spirals, possibly due to its lower mass, low pressure environment & lack of strong spiral arms. $l_{corr}$ being much smaller than the galaxy size suggests that the SF hierarchy does not extend to the full galaxy size & it is likely an effect set by multiple physical mechanisms in the galaxy. The hierarchical distribution of SFCs dissipates within 10 to 50 Myr, signifying their migration away from their birthplaces over time. Our results suggest that the global hierarchical properties of SF in galaxies are not universal & significant variations exist in the local & global hierarchy parameters of a galaxy. This study also demonstrates the capabilities of UVIT in characterizing the SF hierarchy in nearby galaxies. In the future, a bigger sample can be employed to further understand the role of large-scale galaxy properties (morphology, environment) & physical processes (feedback, turbulence, shear & ISM conditions) on determining the non-universal hierarchical properties of SF in galaxies.

We present a sample of 398 galaxies with ionized gas outflow signatures in their spectra from the Galaxy and Mass Assembly (GAMA) Survey Data Release 4, including 45 low-mass galaxies with stellar masses $M_*<10^{10}$ $M_\odot$. We assemble our sample by systematically searching for the presence of a second velocity component in the [O III]$\lambda\lambda 4959, 5007$ doublet emission line in 39,612 galaxies with redshifts $z<0.3$. The host galaxies are classified using the BPT diagram, with $\sim$89% identified as AGNs and composites and 11% as star-forming (SF) galaxies. The outflows are typically faster in AGNs with a median velocity of 936 km s$^{-1}$ compared to 655 km s$^{-1}$ in the SF objects. Of particular interest are the 45 galaxies in the low-mass range, of which a third are classified as AGNs/composites. The outflows from the low-mass AGNs are also faster and more blueshifted compared to those in the low-mass SF galaxies. This indicates that black hole outflows can affect host galaxies in the low-mass range and that AGN feedback in galaxies with $M_*<10^{10}$ $ M_\odot$ should be considered in galaxy evolution models.

In the current era of precision cosmology, the persistence of cosmological tensions, most notably the Hubble tension and the $S_8$ tension, challenges the standard $\Lambda$CDM model. To reconcile these tensions via late-time modifications to expansion history, various features such as phantom crossing in the dark energy equation of state, a negative energy density at high redshifts, etc., are favoured. However, these scenarios cannot be realized within the framework of GR without introducing ghost or gradient instabilities. In this work, we investigate a dynamical dark energy scenario within the framework of Horndeski gravity, incorporating nonminimal coupling to gravity and self-interactions. We highlight that the model can exhibit novel features like phantom crossing and negative dark energy densities at high redshifts without introducing any instabilities. For this specific Horndeski model, we perform a comprehensive analysis of the background evolution along with the effects on perturbations, examining observables like growth rate, matter and CMB power spectrum. To check the consistency of the model with the observational data, we employ MCMC analysis using BAO/$f\sigma_8$, Supernovae, and CMB data. While the model does not outperform the standard $\Lambda$CDM framework in a combined likelihood analysis, there remains a preference for non-zero values of the model parameters within the data. This suggests that dynamical dark energy scenarios, particularly those with non-minimal couplings, merit further exploration as promising alternatives to GR, offering rich phenomenology that can be tested against a broader range of current and upcoming observational datasets.

Diffuse Galactic cirrus, or Diffuse Galactic Light (DGL), can be a prominent component in the background of deep wide-field imaging surveys. The DGL provides unique insights into the physical and radiative properties of dust grains in our Milky Way, and it also serves as a contaminant on deep images, obscuring the detection of background sources such as low surface brightness galaxies. However, it is challenging to disentangle the DGL from other components of the night sky. In this paper, we present a technique for the photometric characterization of Galactic cirrus, based on (1) extraction of its filamentary or patchy morphology and (2) incorporation of color constraints obtained from Planck thermal dust models. Our decomposition method is illustrated using a $\sim$10 deg$^2$ imaging dataset obtained by the Dragonfly Telephoto Array, and its performance is explored using various metrics which characterize the flatness of the sky background. As a concrete application of the technique, we show how removal of cirrus allows low surface brightness galaxies to be identified on cirrus-rich images. We also show how modeling the cirrus in this way allows optical DGL intensities to be determined with high radiometric precision.

Wolf-Rayet (WR) and O-star binaries can be the progenitors of X-ray binaries and double black hole binaries, yet their formation is not fully understood. For 21 observed WR+O systems we aim to infer \rev{if the mass-transfer started on the main sequence (Case A) or later (Case B). We also calculate (limits on) the mass transfer efficiency $\beta$, i.e. the fraction of transferred mass that is accreted and the parameter $\gamma$ that denotes the fraction of angular momentum of the binary that is lost per unit mass in units of the average angular momentum of the binary per unit mass. We infer the possible values for the initial masses based on the observed WR masses and models for WR from the literature. With these initial primary masses we can create a grid of possible periods and secondary masses for which we can determine the values $\beta$ and $\gamma$ would have taken for either Case A or Case B mass transfer. Based on this we can also determine which case of mass transfer is most likely for each system. Taking into account the progenitor distribution of WR+O binaries we find that highly non-conservative Case A mass transfer seems to be the most likely scenario for the majority of systems as this can explain 14 out of 21 systems. The angular momentum loss is likely relatively high (typically $\gamma > 1$). Our finding that most systems in our sample experienced Case-A mass transfer is at odds with the expectation that most massive binaries go through Case B mass transfer. This suggest post-case-B systems are significantly underrepresented in the observed WR+O binary population, intrinsically or due to severe selection effects.

We introduce the radiative transfer postprocessing code Subsweep. The code is based on the method of transport sweeps, in which the exact solution to the scattering-less radiative transfer equation is computed in a single pass through the entire computational grid. The radiative transfer module is coupled to radiation chemistry, and chemical compositions as well as temperatures of the cells are evolved according to photon fluxes computed during radiative transfer. Subsweep extends the method of transport sweeps by incorporating sub-timesteps in a hierarchy of partial sweeps of the grid. This alleviates the need for a low, global timestep and as a result Subsweep is able to drastically reduce the amount of computation required for accurate integration of the coupled radiation chemistry equations. We succesfully apply the code to a number of physical tests such as the expansion of HII regions, the formation of shadows behind dense objects, and its behavior in the presence of periodic boundary conditions.

A new giant outburst of the Be X-ray binary RX J0520.5-6932 was detected and subsequently observed with several space-borne and ground-based instruments. This study presents a comprehensive analysis of the optical and X-ray data, focusing on the spectral and timing characteristics of selected X-ray observations. A joint fit of spectra from simultaneous observations performed by the X-ray telescope (XRT) on the Neil Gehrels Swift Observatory (Swift) and Nuclear Spectroscopic Telescope ARray (NuSTAR) provides broadband parameter constraints, including a cyclotron resonant scattering feature (CRSF) at 32.2(+0.8/-0.7) keV with no significant energy change since 2014, and a weaker Fe line. Independent spectral analyses of observations by the Lobster Eye Imager for Astronomy (LEIA), Einstein Probe (EP), Swift-XRT, and NuSTAR demonstrate the consistency of parameters across different bands. Luminosity variations during the current outburst were tracked. The light curve of the Optical Gravitational Lensing Experiment (OGLE) aligns with the X-ray data in both 2014 and 2024. Spin evolution over 10 years is studied after adding Fermi Gamma-ray Burst Monitor (GBM) data, improving the orbital parameters, with an estimated orbital period of 24.39 days, slightly differing from OGLE data. Despite intrinsic spin-up during outbursts, a spin-down of ~0.04s over 10.3 years is suggested. For the new outburst, the pulse profiles indicate a complicated energy-dependent shape, with decreases around 15 keV and 25 keV in the pulsed fraction, a first for an extragalactic source. Phase-resolved NuSTAR data indicate variations in parameters such as flux, photon index, and CRSF energy with rotation phase.

The Wide Area Linear Optical Polarimeter North (WALOP-North) is an optical polarimeter designed for the needs of the PASIPHAE survey. It will be installed on the 1.3m telescope at the Skinakas Observatory in Crete, Greece. After commissioning, it will measure the polarization of millions of stars at high Galactic latitude, aiming to measure hundreds of stars per $deg^2$. The astronomical filter used in the instrument is a modified, polarimetrically-neutral broadband SDSS-r. This instrument will be pioneering one due to its large field-of-view (FoV) of $30\times 30$ $arcmin^2$ and high accuracy polarimetry measurements. The accuracy and sensitivity of the instrument in polarization fraction will be at the 0.1\% and 0.05\% level, respectively. Four separate 4k$\times$4k CCDs will be used as the instrument detectors, each imaging one of the $0\deg{}, 45\deg{}, 90\deg{}$ and $135\deg{}$ polarized FoV separately, therefore making the instrument a four-channel, one-shot polarimeter. Here, we present the overall optical design of the instrument, emphasizing on the aspects of the instrument that are different from WALOP-South. We also present a novel design of filters appropriate for polarimetry along with details on the management of the instrument size and its polarimetric calibration.

We propose to constrain the primordial (local-type) non-Gaussianity signal by first reconstructing the initial density field to remove the late time non-Gaussianities introduced by gravitational evolution. Our reconstruction algorithm combines perturbation theory on large scales with a convolutional neural network on small scales. We reconstruct the squared potential (that sources the non-Gaussian signal) out to $k=0.2\ h$/Mpc to an accuracy of 99.8%. We cross-correlate this squared potential field with the reconstructed density field and verify that this computationally inexpensive estimator has the same information content as the full matter bispectrum. As a proof of concept, our approach can yield up to a factor of three improvement in the $f_{\rm NL}$ constraints, although it does not yet include the complications of galaxy bias or imperfections in the reconstruction. These potential improvements make it a promising alternative to current approaches to constraining primordial non-Gaussianity.

Dense stellar clusters surround the supermassive black holes (SMBH) in galactic nuclei. Interactions within the cluster can alter the stellar orbits, occasionally driving a star into the SMBH's tidal radius where it becomes ruptured. This proof-of-concept study examines the orbital effects of stellar collisions using a semianalytic model. Both low and high speed collisions occur in the SMBH's sphere of influence. Our model treats stars in low speed collisions as sticky spheres. For high-speed collisions, we develop a simple prescription based on the limiting case of a hyperbolic encounter. We test a range of collision treatments and cluster conditions. We find that collisions can place stars on nearly radial orbits. Depositing stars within the tidal radius, collisions may drive the disruption of stars with unusual masses and structures: depending on the nature of the collision, the star could be the product of a recent merger, or it could have lost its outer layers in a high speed impact, appearing as a stripped star. We also find that high speed collisions near the periapsis of an eccentric orbit can unbind stars from the SMBH. However, dissipation during these high-speed collisions can substantially reduce the number of unbound stars achieved in our simulations. We conclude that TDEs and ejected stars, even in the hypervelocity regime, are plausible outcomes of stellar collisions, though their frequency in a three-dimensional nuclear star cluster are uncertain. Future work will address the rates and properties of these events.

Deep polarization surveys at low radio frequencies are key to cosmic magnetism studies: Larger catalogs of polarized extragalactic sources and increased precision on Faraday rotation measures (RMs) make it possible to probe the magneto-ionic medium along the lines of sight of the sources and to construct denser RM grids. In a first paper, we presented a search for polarized sources in deep observations of the 25 square degree area of the European Large Area ISO Survey North 1 (ELAIS-N1) field with the LOw Frequency ARray (LOFAR) in the range 114.9 to 177.4 MHz. In this paper, we investigate the properties of the polarized radio galaxies and use the catalog to produce an RM grid of the field. After identifying the host galaxies and collecting redshift information, we characterized the radio galaxies in terms of their radio morphologies, rest frame radio luminosities, and linear sizes. We calculated residual rotation measures (RRMs) by removing the Galactic RM and studied the variation in the RRMs with redshift and degree of polarization. We produced an RRM grid of the field and compared the positions of the polarized sources with those of galaxy clusters and superclusters. The radio galaxies show a variety of morphologies, including diffuse emission; Fanaroff Riley type II sources make up about half of the sample. Using available multiband catalogs, we found redshifts for the hosts of all polarized sources in the range of 0.06 to 1.9. Polarized emission is detected mainly from large radio galaxies. The RRM values have a median close to zero, and they appear to be independent of redshift and degree of polarization. The sources in the lines of sight of clusters of galaxies and of a supercluster are indistinguishable in their polarization and RRM properties from the population of sources that are not behind these structures.

This paper presents initial results of a systematic search for resonance X-ray absorption lines from H-like O VIII and He-like O VII caused by the intervening warm-hot intergalactic medium (WHIM). The search is based on far ultra-violet redshift priors from O VI and H I broad Lyman-alpha lines that were previously detected by HST and FUSE in a sample of 51 sources with either XMM-Newton or Chandra data, for a total X-ray redshift path of $\Delta z$ = 10.9. Of the 1,224 absorption-line systems with FUV priors that were analyzed, 33 systems feature an absorption-line feature detected with $\geq$99 % confidence at the same redshift of the FUV prior, some coincident with previously reported absorption line detections. The ultimate goal of this search is to test the hypothesis that X-ray absorbing WHIM gas is the repository of the missing baryons in the local universe. Further results and the cosmological implications of this analysis are presented in a companion paper.

I describe a new method of estimating the prevalence of life in the Universe, based on the fact that more chemically complex environments are more rare. The paper makes three main claims: (1) There is a statistically significant (inverse) relationship between chemical complexity (quantified as the number of different types of molecules present in a given environment) and mass fraction for the successively smaller environments in the hierarchy of cosmic matter (extragalactic medium, interstellar clouds, dense cores, planetary systems, their icy fraction etc.) that is well described by a logarithmic law. (2) Minimal chemical complexity of life can be roughly defined, based on existing studies in vitro and in silico, both bottom-up (designing increasingly complex chemical systems) and top-down (simplifying minimal organisms). (3) Thus, one can estimate the fraction of the total mass density of the Universe that resides in reservoirs of chemical complexity estimated as being minimal for life. This is then translated, through simple statistical models of planetary systems, into the number of planets in a single Milky Way-sized galaxy that have, on their surface, reservoirs of biogenic chemical complexity. Two best models give the estimates of 1.6 (more complex minimal life) and 1.3e4 (slightly less complex minimal life) as the predicted upper bound for the number of instances of life per our Galaxy.

Asymptotic giant branch (AGB) stars play a significant role in our understanding of the origin of the elements. They contribute to the abundances of C, N, and approximately $50\%$ of the abundances of the elements heavier than iron. An aspect often neglected in studies of AGB stars is the impact of a stellar companion on AGB stellar evolution and nucleosynthesis. In this study, we update the stellar abundances of AGB stars in the binary population synthesis code \textsc{binary\_c} and calibrate our treatment of the third dredge-up using observations of Galactic carbon stars. We model stellar populations of low- to intermediate-mass stars at solar-metallicity and examine the stellar wind contributions to C, N, O, Sr, Ba, and Pb yields at binary fractions between 0 and 1. For a stellar population with a binary fraction of 0.7, we find $\sim 20-25\%$ less C and $s$-process elements ejected than from a population composed of only single stars, and we find little change in the N and O yields. We also compare our models with observed abundances from Ba stars and find our models can reproduce most Ba star abundances, but our population estimates a higher frequency of Ba stars with a surface [Ce/Y] > $+0.2\,$dex. Our models also predict the rare existence of Ba stars with masses $> 10 \text{M}\,_\odot$.

Based on 2-minute cadence TESS data, 20 confident independent frequencies were identified for the star TIC 120857354. The Kolmogorov-Smirnov test reveals a rotational splitting of 2.40 $\mu$Hz and a uniform frequency spacing of 74.6 $\mu$Hz. Subsequently, five sets of rotational splittings were discerned, including a quintuplet and four pairs of doublets, aligning with the characteristics of p-mode rotational splitting. Based on the sets of rotational splittings and the uniform frequency spacing, we finally identified 4 radial modes, 6 dipole modes, and 10 quadrupole modes. Furthermore, we found that the frequency separations within the $\ell$ = 2 sequences show a decreasing trend towards lower-order modes, analogous to the $\ell$ = 0 sequences. A grid of theoretical models were computed to match the identified frequencies, revealing that TIC 120857354 is a main-sequence star with $M$ = 1.54 $\pm$ 0.04 $M_{\odot}$, $Z$ = 0.015 $\pm$ 0.003, $T_{\rm eff}$ = 7441 $\pm$ 370 K, $\log g$ = 4.27 $\pm$ 0.01, $R$ = 1.52 $\pm$ 0.01 $R_{\odot}$, $L$ = 6.33 $\pm$ 1.53 $L_{\odot}$, age = 0.53 $\pm$ 0.07 Gyr, and $X_c/X_0$ = 0.84 $\pm$ 0.05. In-depth analyses suggest that $\ell$ = 2 may be p-dominated mixed modes with pronounced g-mode characteristics, enabling us to probe deeper into interiors of the star and determine the relative size of the convective core to be $R_c/R$ = 0.092 $\pm$ 0.002.

Asteroseismic masses of globular cluster (GC) stars are invaluable to investigate stellar evolution. Previously, only two GCs have been seismically studied. We present new detections of solar-like oscillations in the clusters M9 and M19, focusing on two key areas: stellar mass loss and GC multiple populations. Using K2 photometry, we detect solar-like oscillations in stars on the red giant branch and early asymptotic giant branch. We measure an integrated mass-loss for M9 of $0.16\pm0.02$(rand)$\pm0.03$(sys)$M_{\odot}$ and M19 of $0.33\pm0.03$(rand)$^{+0.09}_{-0.07}$(sys)$M_{\odot}$. Comparing these to the mass-loss estimates from previous seismically studied clusters, we derive a preliminary relationship between stellar mass-loss and metallicity for Type I GCs. We find that the mass-loss for M19 -- a Type II GC -- is significantly larger, suggesting Type II clusters follow a different mass-loss-metallicity trend. We also examine the mass distributions in each evolutionary phase for evidence of a bimodality that could indicate mass differences between sub-populations. While no clear bimodality is observed, there is tentative evidence suggesting the presence of two mass populations. Classification through spectroscopic abundances into the sub-populations is needed to verify these findings. This study reinforces that asteroseismology of GC stars provides an excellent testbed for studying stellar evolution. However, to advance the field we need high-quality photometry of more GCs, a goal that could be realised with the upcoming Roman Telescope.

In this paper, we perform a follow-up investigation of the solar eruption originating from active region (AR) 13575 on 2024 February 9. The primary eruption of a hot channel (HC) generates an X3.4 class flare, a full-halo coronal mass ejection (CME), and an extreme-ultraviolet (EUV) wave. Interaction between the wave and a quiescent prominence (QP) leads to a large-amplitude, transverse oscillation of QP. After the transverse oscillation, QP loses equilibrium and rises up. The ascending motion of the prominence is coherently detected and tracked up to 1.68 R by the Solar UltraViolet Imager (SUVI) onboard the GOES-16 spacecraft and up to 2.2 R by the Solar Corona Imager (SCI UV) of the Lyman-alpha Solar Telescope (LST) onboard the ASO-S spacecraft. The velocity increases linearly from 12.3 to 68.5 km s at 18:30 UT. The sympathetic eruption of QP drives the second CME with a typical three-part structure. The bright core comes from the eruptive prominence, which could be further observed up to 3.3 R by the Large Angle Spectroscopic Coronagraph (LASCO) onboard the SOHO mission. The leading edge of the second CME accelerates continuously from 120 to 277 kms. The EUV wave plays an important role in linking the primary eruption with the sympathetic eruption.

Failure of a filament eruption caused by magnetic reconnection between the erupting filament and the overlying magnetic field has been previously proposed in numerical simulations. It is, however, rarely observed. In this study, we report the reconnection between an erupting filament and its overlying coronal loops, that results in the failure of the filament eruption. On 2023 September 24, a filament was located in active region 13445. It slowly rose, quickly erupted, rapidly decelerated, and finally stopped, with an untwisting motion. As a failed eruption, the event is associated with an M4.4 flare but no coronal mass ejection. During the eruption, the filament became bright, and the overlying loops appeared first in the high-temperature channels. They have average temperatures of ~12.8 and ~9.6MK, respectively, indicating that both of them were heated. Two sets of new loops, separately connecting the filament endpoints and the overlying loop footpoints, then formed. Subsequently, the heated overlying loops were seen sequentially in the low-temperature channels, showing the cooling process, which is also supported by the light curves. Plasmoids formed, and propagated bidirectionally along the filament and the overlying loops, indicating the presence of plasmoid instability. These results suggest that reconnection occurs between the erupting filament and the overlying loops. The erupting filament eventually disappeared, with the appearance of more newly-formed loops. We propose that the reconnection between the erupting filament and the overlying loops ruins the filament completely, and hence results in the failed eruption.

Pulsar timing arrays are ensembles of regularly observed millisecond pulsars timed to high precision. Each pulsar in an array could be affected by a suite of noise processes, most of which are astrophysically motivated. Analysing them carefully can be used to understand these physical processes. However, the primary purpose of these experiments is to detect signals that are common to all pulsars, in particular signals associated with a stochastic gravitational wave background. To detect this, it is paramount to appropriately characterise other signals that may otherwise impact array sensitivity or cause a spurious detection. Here we describe the second data release and first detailed noise analysis of the pulsars in the MeerKAT Pulsar Timing Array, comprising high-cadence and high-precision observations of $83$ millisecond pulsars over $4.5$ years. We use this analysis to search for a common signal in the data, finding a process with an amplitude of $\log_{10}\mathrm{A_{CURN}} = -14.25^{+0.21}_{-0.36}$ and spectral index $\gamma_\mathrm{CURN} = 3.60^{+1.31}_{-0.89}$. Fixing the spectral index at the value predicted for a background produced by the inspiral of binary supermassive black holes, we measure the amplitude to be $\log_{10}\mathrm{A_{CURN}} = -14.28^{+0.21}_{-0.21}$ at a significance expressed as a Bayes factor of $\ln(\mathcal{B}) = 4.46$. Under both assumptions, the amplitude that we recover is larger than those reported by other PTA experiments. We use the results of this analysis to forecast our sensitivity to a gravitational wave background possessing the spectral properties of the common signal we have measured.

We present a novel representation learning method for downstream tasks such as anomaly detection and unsupervised transient classification in high-energy datasets. This approach enabled the discovery of a new fast X-ray transient (FXT) in the Chandra archive, XRT 200515, a needle-in-the-haystack event and the first Chandra FXT of its kind. Recent serendipitous breakthroughs in X-ray astronomy, including FXTs from binary neutron star mergers and an extragalactic planetary transit candidate, highlight the need for systematic transient searches in X-ray archives. We introduce new event file representations, E-t Maps and E-t-dt Cubes, designed to capture both temporal and spectral information, effectively addressing the challenges posed by variable-length event file time series in machine learning applications. Our pipeline extracts low-dimensional, informative features from these representations using principal component analysis or sparse autoencoders, followed by clustering in the embedding space with DBSCAN. New transients are identified within transient-dominant clusters or through nearest-neighbor searches around known transients, producing a catalog of 3,539 candidates (3,427 flares and 112 dips). XRT 200515 exhibits unique temporal and spectral variability, including an intense, hard <10 s initial burst followed by spectral softening in an ~800 s oscillating tail. We interpret XRT 200515 as either the first giant magnetar flare observed at low X-ray energies or the first extragalactic Type I X-ray burst from a faint LMXB in the LMC. Our method extends to datasets from other observatories such as XMM-Newton, Swift-XRT, eROSITA, Einstein Probe, and upcoming missions like AXIS.

Pulsar Timing Arrays search for nanohertz-frequency gravitational waves by regularly observing ensembles of millisecond pulsars over many years to look for correlated timing residuals. Recently the first evidence for a stochastic gravitational wave background has been presented by the major Arrays, with varying levels of significance ($\sim$2-4$\sigma$). In this paper we present the results of background searches with the MeerKAT Pulsar Timing Array. Although of limited duration (4.5 yr), the $\sim$ 250,000 arrival times with a median error of just $3 \mu$s on 83 pulsars make it very sensitive to spatial correlations. Detection of a gravitational wave background requires careful modelling of noise processes to ensure that any correlations represent a fit to the underlying background and not other misspecified processes. Under different assumptions about noise processes we can produce either what appear to be compelling Hellings-Downs correlations of high significance (3-3.4$\sigma$) with a spectrum close to that which is predicted, or surprisingly, under slightly different assumptions, ones that are insignificant. This appears to be related to the fact that many of the highest precision MeerKAT Pulsar Timing Array pulsars are in close proximity and dominate the detection statistics. The sky-averaged characteristic strain amplitude of the correlated signal in our most significant model is $h_{c, {\rm yr}} = 7.5^{+0.8}_{-0.9} \times 10^{-15}$ measured at a spectral index of $\alpha=-0.26$, decreasing to $h_{c, {\rm yr}} = 4.8^{+0.8}_{-0.9} \times 10^{-15}$ when assessed at the predicted $\alpha=-2/3$. These data will be valuable as the International Pulsar Timing Array project explores the significance of gravitational wave detections and their dependence on the assumed noise models.

We perform five 3D magnetohydrodynamic (MHD) core-collapse supernova simulations for non-rotating progenitors between 9.5 $M_\odot$ and 24 $M_\odot$. Four of the five models produce explosions while one fails. The exploding models are extended to between 0.9 s and 1.6 s post-bounce to study a possible impact of magnetic fields on explosion and remnant properties. Diagnostic explosion energies grow at a similar pace as in previous non-magnetic models. They reach between 0.11 foe and 0.61 foe, but are still growing by the end of the simulations. Neutron star kicks reach no more than 300 km s$^{-1}$, and although these are also still growing, they are unlikely to be in conflict with observed pulsar velocities. Extrapolated neutron star spin periods are between 45 ms and 1.8 s, consistent with observed birth spin rates. Magnetic torques only contribute about 10% to the spin-up of the neutron star. The inclusion of magnetic fields does not provide a mechanism for spin-kick alignment in our simulations. Surface dipole fields are in the range of $10^{12}-10^{13}$ G, much smaller than the root-mean-square field strength. Different from previous simulations, magnetic fields in the gain region only reach at most O(1%) of kinetic equipartition, likely because relatively early shock revival cuts off accretion as a power source for field amplification, which appears to be driven primarily by shear flows at the bottom of the gain region.

Radial metallicity gradients are fundamental to understanding galaxy formation and evolution. In our high-resolution simulation of a NIHAO-UHD Milky Way analogue, we analyze the linearity, scatter, spatial coherence, and age-related variations of metallicity gradients using young stars and gas. While a global linear model generally captures the gradient, it ever so slightly overestimates metallicity in the inner galaxy and underestimates it in the outer regions of our simulated galaxy. Both a quadratic model, showing an initially steeper gradient that smoothly flattens outward, and a piecewise linear model with a break radius at 10~kpc (2.5 effective radii) fit the data equally better. The spread of [Fe/H] of young stars in the simulation increases by tenfold from the innermost to the outer galaxy at a radius of 20~kpc. We find that stars born at similar times along radial spirals drive this spread in the outer galaxy, with a chemical under- and over-enhancement of up to 0.1 dex at leading and trailing regions of such spirals, respectively. This localised chemical variance highlights the need to examine radial and azimuthal selection effects for both Galactic and extragalactic observational studies. The arguably idealised but volume-complete simulations suggest that future studies should not only test linear and piecewise linear gradients, but also non-linear functions such as quadratic ones to test for a smooth gradient rather than one with a break radius. Either finding would help to determine the importance of different enrichment or mixing pathways and thus our understanding of galaxy formation and evolution scenarios.

Quasi-periodic eruptions (QPEs) are a novel class of transients recently discovered in a few extragalactic nuclei. It has been suggested that a QPE can be produced by a main-sequence star undergoing repeated partial disruptions by the tidal field of a supermassive black hole (SMBH) immediately after getting captured on a tightly bound orbit through the Hills mechanism. In this paper, we investigate the period-dependent formation rate of QPEs for this scenario, utilizing scattering experiments and the loss-cone theory. We calculate the QPE formation rates in both a single-SMBH and a dual-SMBHs system, motivated by the over-representation of post-merger galaxies as QPE hosts. We find that for SMBHs of mass $10^{6}-10^{7}M_{\odot}$, most QPEs formed in this scenario have periods longer than $\simeq 100$ days. A single-SMBH system generally produces QPEs at a negligible rate of $10^{-10}-10^{-8}\ \rm{yr}^{-1}$ due to inefficient two-body relaxation. While in a dual-SMBHs system, the QPE rate is enhanced by $3-4$ orders of magnitude, mainly due to a boosted angular momentum evolution under tidal perturbation from the companion SMBH (galaxy). The QPE rate in a post-merger galactic nucleus hosting two equal-mass SMBHs separated by a few parsecs could reach $10^{-6}-10^{-5}\ \rm{yr}^{-1}$. Our results suggest that a non-negligible fraction ($\simeq 10-90\%$) of long-period QPEs should come from post-merger galaxies.

Understanding how cosmic rays (CRs) propagate within the giant molecular clouds (GMCs) is critical for studying the dynamics and chemical processes inside the clouds. The flux of low-energy CRs inside the dense cores of GMCs strongly affects the heating and ionization of the gases and further influences the star-forming process. We analytically calculated the CR distribution inside GMCs assuming different diffusion coefficients, and estimated the corresponding nuclear de-excitation line emission and the ionization rate resulting from the interaction between the penetrating CRs and gases. We find that future MeV observations can be used as a unique probe to measure the low-energy CR density in situ and test different CR propagation scenario inside GMCs.

The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment located in the Atacama Desert in Chile at an elevation of 5200 meters, nominally consisting of an array of three 0.42-meter small aperture telescopes (SATs) and one 6-meter large aperture telescope (LAT). SO will make accurate measurements of the CMB temperature and polarization spanning six frequency bands ranging from 27 to 280 GHz, fielding a total of $\sim$68,000 detectors covering angular scales between one arcminute to tens of degrees. In this paper, we focus on the SATs, which are tailored to search for primordial gravitational waves, with the primary science goal of measuring the primordial tensor-to-scalar ratio \textit{r} at a target level of $\sigma(r) \approx 0.003$. We discuss the design drivers, scientific impact, and current deployment status of the three SATs, which are scheduled to start taking data in the coming year. The SATs aim to map 10\% of the sky at a 2 $\mu$K-arcmin noise level observing at mid-frequencies (93/145 GHz), with additional ultra-high-frequency (225/280 GHz) and low-frequency (27/39 GHz) targets to yield galactic foreground-subtracted measurements.

The Simons Observatory (SO) is a cosmic microwave background (CMB) experiment located in the Atacama Desert in Chile that will make precise temperature and polarization measurements over six spectral bands ranging from 27 to 285 GHz. Three small aperture telescopes (SATs) and one large aperture telescope (LAT) will house $\sim$60,000 detectors and cover angular scales between one arcminute and tens of degrees. We present the performance of the dichroic, low-frequency (LF) lenslet-coupled sinuous antenna transition-edge sensor (TES) bolometer arrays with bands centered at 27 and 39 GHz. The LF focal plane will primarily characterize Galactic synchrotron emission as a critical part of foreground subtraction from CMB data. We will discuss the design, optimization, and current testing status of these pixels.

In an accompanying publication, the MeerKAT Pulsar Timing Array (MPTA) collaboration reports tentative evidence for the presence of a stochastic gravitational-wave background, following observations of similar signals from the European and Indian Pulsar Timing Arrays, NANOGrav, the Parkes Pulsar Timing Array and the Chinese Pulsar Timing Array. If such a gravitational-wave background signal originates from a population of inspiraling supermassive black-hole binaries, the signal may be anisotropically distributed on the sky. In this Letter we evaluate the anisotropy of the MPTA signal using a spherical harmonic decomposition. We discuss complications arising from the covariance between pulsar pairs and regularisation of the Fisher matrix. Applying our method to the 4.5 yr dataset, we obtain two forms of sky maps for the three most sensitive MPTA frequency bins between 7 -21 nHz. Our "clean maps'' estimate the distribution of gravitational-wave strain power with minimal assumptions. Our radiometer maps answer the question: is there a statistically significant point source? We find a noteworthy hotspot in the 7 nHz clean map with a $p$-factor of $p=0.015$ (not including trial factors). Future observations are required to determine if this hotspot is of astrophysical origin.

We introduce a new method designed for Bayesian inference of the angular power spectrum of the Gravitational Wave Background (GWB) anisotropy. This scheme works with time-series data and can optionally incorporate the cross-correlations between the GWB anisotropy and other cosmological tracers, enhancing the significance of Bayesian inference. We employ the realistic LISA response and noise model to demonstrate the validity of this approach. The findings indicate that, without considering any cross-correlations, the 4-year LISA data is insufficient to achieve a significant detection of multipoles. However, if the anisotropies in the GWB are strongly correlated with the Cosmic Microwave Background (CMB), the 4-year data can provide unbiased estimates of the quadrupole moment ($\ell = 2$). This reconstruction process is generic and not restricted to any specific detector, offering a new framework for extracting anisotropies in the GWB data from various current and future gravitational wave observatories.

The Centaurus A radio galaxy, due to its proximity, presents itself as one of the few systems that allow the study of relativistic jet outflows at sub-parsec distances from the central supermassive black holes, with high signal to noise. We present the results from the first multi-epoch spectropolarimetric observations of Centaurus A at milliarcsecond resolution, with a continuous frequency coverage of $4.59-7.78$\,GHz. Using a Bayesian framework, we perform a comprehensive study of the jet kinematics, and discuss aspects of the jet geometry including the jet inclination angle, jet opening angle, and the jet expansion profile. We calculate an upper limit on the jet's inclination to the line of sight to be $<25^{\circ}$, implying the lower limit on the intrinsic jet speed to be $0.2$\,c. On the observed VLBA scales we detect new jet components launched by the central engine since our previous study. Using the observed frequency-dependent core shift in Centaurus A, we find the jet to have reached constant bulk speed and conical outflow at the regions probed by the base of the jet at $7.78- 4.59$\,GHz, and we also estimate the location of the central black hole further upstream. Through polarimetric analysis (by applying RM synthesis for the first time on VLBI data), we find evidence to suggest the possible onset of acceleration towards the leading edge of Centaurus A's subparsec-scale jet studied here.

As the most energetic explosion in the universe, gamma-ray bursts (GRBs) are usually believed to be generated by relativistic jets. Some mechanisms (e.g. internal non-uniform magnetic dissipation processes or the precession of the central engine) may generate asymmetric jet structures, which is characterized by multiple fluctuations in the light curve of afterglow. Since the jet's structure introduces asymmetry in radiation around the line of sight (LOS), it is naturally expected that polarization will be observable. In this work, we reveal the polarization characteristics of gamma-ray burst afterglows with a non-axisymmetric structured jet. Our results show that the afterglow signal generally exhibits polarization, with the degree and evolution influenced by the specific jet structure, observing frequency, and the line of sight (LOS). The polarization degree is notably higher when the LOS is outside the jet. This degree fluctuates over time as different regions of radiation alternate in their dominance, which is accompanied by the rotation of the polarization angle and further reflects the intricate nature of the jet. Regarding its evolution over frequency, the polarization degree displays significant fluctuations at spectral breaks, with the polarization angle possibly undergoing abrupt changes. These features may provide strong evidence for future identification of potential GRBs with asymmetric jet structures.

The broadband afterglow of Gamma-ray bursts (GRBs) is usually believed to originate from the synchrotron radiation of electrons accelerated by the external shock of relativistic jets. Therefore, the jet structure should have a significant impact on the GRB afterglow features. The latest observations indicate that the GRB jets may possess intricate structures, such as Gaussian structure, power-law structure, or jet-cocoon structure. Most recently, an abnormal afterglow of GRB 210731A has raised extensive attention, whose optical afterglow exhibites multiple rebrightening phenomena within 4 hours, posing a serious challenge to the standard afterglow model. Here we intend to interpret the characteristics of GRB 210731A afterglows within the framework of non-axisymmetric structured jets, where multiple distinct peaks in the afterglow light curve are caused by the uneven distribution of energy and velocity within the jet in the azimuth angle direction. Through Monte Carlo Markov Chain fitting, we show that a three-component asymmetric structured jet can well explain the multi-band afterglow data. The energy difference among the three components is about 1.5 orders of magnitude, with higher-energy components exhibiting slower speeds. The radiation contribution of each component has sequentially dominated the light curve of the afterglow, resulting in multiple peaks, with the highest peak occurring at the latest time. We suggest that in the future, polarization observations should be conducted on afterglows with multiple brightening signatures, which will help to effectively distinguish the structured jet model from other alternative models, such as energy injection, and ultimately help to determine the true configuration of jets.

Filaments play a crucial role in providing the necessary environmental conditions for star formation, actively participating in the process. To facilitate the identification and analysis of filaments, we introduce DPConCFil (Directional and Positional Consistency between Clumps and Filaments), a suite of algorithms comprising one identification method and two analysis methods. The first method, the consistency-based identification approach, uses directional and positional consistency among neighboring clumps and local filament axes to identify filaments in the PPV datacube. The second method employs a graph-based skeletonization technique to extract the filament intensity skeletons. The third method, a graph-based substructuring approach, allows the decomposition of complex filaments into simpler sub-filaments. We demonstrate the effectiveness of DPConCFil by applying the identification method to the clumps detected in the Milky Way Imaging Scroll Painting (MWISP) survey dataset by FacetClumps, successfully identifying a batch of filaments across various scales within $10^{\circ} \leq l \leq 20^{\circ}$, $-5.25^{\circ} \leq b \leq 5.25^{\circ}$ and -200 km s$^{-1}$ $\leq v \leq$ 200 km s$^{-1}$. Subsequently, we apply the analysis methods to the identified filaments, presenting a catalog with basic parameters and conducting statistics of their galactic distribution and properties. DPConCFil is openly available on GitHub, accompanied by a manual.

The magnetic field is a significant and universal physical phenomenon in modern astrophysics. Small-scale magnetic fields are very important in the stellar atmosphere. They are ubiquitous, and strongly couple with the acoustic waves. Therefore, their presence affects the properties of acoustic waves in the stellar outer layer. In the present work, under the assumption that the small-scale magnetic features are the cause of the asteroseismic surface term (the frequency-dependent frequency offset between stars and their models), we explore the strength of such fields in the solar analog KIC 8006161. By considering the effect of small-scale magnetic fields in the stellar photosphere, we use the observed oscillation frequencies to constrain the inner structures and surface small-scale magnetic fields of solar-like star KIC 8006161. To agree with the existing observations, such as oscillation frequencies, and their frequency separation ratios, the theoretical model requires a small-scale magnetic field to form a magnetic-arch splicing layer in the stellar outer atmosphere. The small-scale magnetic field strengths for KIC 8006161 obtained from best-fit model with $Y_{\rm init} = 0.249+1.33Z_{\rm init}$ and $Y_{\rm init}$ as a free parameter, are approximately 96 G and 89 G, respectively. The corresponding locations of the magnetic-arch splicing layer are about $522$ km and 510 km, respectively.

Over the last several decades, extensive research has been conducted on the baryon cycles within cosmic structures, encompassing a broad mass range from dwarf galaxies to galaxy clusters. However, a notable gap in understanding the cosmic baryon cycle is the poor galaxy groups with halo masses around $10^{13}\ M_{\odot}$ (e.g., McGaugh et al. 2010). Poor galaxy groups, like our own Local Group, are prevalent throughout the universe, yet robust detection of their hot, X-ray emitting intragroup medium (IGrM) has remained elusive. The presence of this hot IGrM is crucial for addressing the long-standing "missing baryons" problem. Previous ROSAT-based studies were limited by a small number of X-ray bright samples, thus restricting the scope of their findings. Here we show a robust detection of this hot IGrM in a large, optically selected poor groups sample, based on the stacked X-ray images from the eROSITA Final Equatorial Depth Survey. These groups are identified in DESI LS with a mass range of log($M_\mathrm{halo}/h^{-1}M_{\odot}$) = 11.5-13.5 and a redshift range of z = 0.1-0.5. Additionally, our results indicate that despite its presence in virtually groups at all sizes, this gas component is still not sufficient to recover the universal baryon fraction, and hence the "missing baryons" problem still persists in poor galaxy groups.

Warm rocky exoplanets within the habitable zone of Sun-like stars are favoured targets for current and future missions. Theory indicates these planets could be wet at formation and remain habitable long enough for life to develop. In this work we test the climate-chemistry response, maintenance, and detectability of biosignatures in warm, water-rich atmospheres with Earth biomass fluxes within the framework of the planned LIFE mission. We used the coupled climate-chemistry column model 1D-TERRA to simulate the composition of planetary atmospheres at different distances from the Sun, assuming Earth's planetary parameters and evolution. We increased the incoming instellation by up to 50 percent in steps of 10 percent, corresponding to orbits of 1.00 to 0.82 AU. Simulations were performed with and without modern Earth's biomass fluxes. Emission spectra of all simulations were produced using the GARLIC radiative transfer model. LIFEsim was then used to add noise to and simulate observations of these spectra to assess how biotic and abiotic atmospheres of Earth-like planets can be distinguished. Increasing instellation leads to surface water vapour pressures rising from 0.01 bar (1.13%) to 0.61 bar (34.72%). In the biotic scenarios, the ozone layer survives because hydrogen oxide reactions with nitrogen oxides prevent the net ozone chemical sink from increasing. Synthetic observations with LIFEsim, assuming a 2.0 m aperture and resolving power of R = 50, show that O3 signatures at 9.6 micron reliably point to Earth-like biosphere surface fluxes of O2 only for systems within 10 parsecs. Increasing the aperture to 3.5 m increases this range to 22.5 pc. The differences in atmospheric temperature due to differing H2O profiles also enables observations at 15.0 micron to reliably identify planets with a CH4 surface flux equal to that of Earth's biosphere.

We present an analysis of the metal-poor galaxy spectra in the redshift range 0.00574$\leq$z$\leq$0.05368 which were reported by Nakajima et al (2022) in their EMPG (extreme metal poor galaxy) sample. The models account for the active galactic nuclei (AGN) and the starburst (SB) galaxies, for accretion and ejection, for the physical parameters and the element abundances. The results are obtained in particular for the two cases, the emitting nebula is ejected outward from the galaxy radiation source (RS) and the emitting nebula is accreted towards the RS. We adopt the code {\sc suma} which allows to choose the direction of the clouds relative to the RS. The modelling results which reproduce a single galaxy spectrum with the highest precision allow to classify this object as an AGN ejecting, an AGN accreting, an SB ejecting or an SB accreting type. When more models are equally valid we suggest that the galaxy is the product of merging. Our results show that among the eleven sample galaxies five are such. We focus on the N/O trends with the oxygen metallicity and with the redshift to identify the nitrogen/oxygen relative formation processes and the process-rates, respectively, for intermediate-mass stars. Our results show that O/H relative abundances calculated for the sample galaxies are lower than solar by a factor $\leq$5. Yet, a few values were found above solar. He/H were calculated lower than solar by factors $\leq$ 100 and N/H by factors $\leq$135.

Recent observations have revealed an unusual stellar distribution within the almost dark dwarf galaxy Nube. The galaxy exhibits a remarkably flat stellar distribution, with an effective radius of approximately 6.9 kpc, exceeding the typical size of dwarf galaxies and even surpassing that of ultra-diffuse galaxies (UDGs) with similar stellar masses. The dynamical heating effect of fuzzy dark matter (FDM) may offer an explanation for this extremely diffuse stellar distribution in Nube. In this research, we utilize simulation techniques to investigate this issue and find that a particle mass $\mathcal{O} (1)\times 10^{-23}$ eV offers a plausible explanation for this peculiar stellar distribution anomaly.

Investigating the ionizing emission of star-forming galaxies is critical to understanding their contribution to reionization and their impact on the surrounding environment. The number of ionizing photons available to reionize the intergalactic medium (IGM) depends not only on the abundance of galaxies but also on their efficiency in producing ionizing photons ($\xi_{ion}$). We aim to estimate the $\xi_{ion}$ using Balmer lines in a sample of 731 galaxies at $4\leq z \leq 10$ selected from different JWST surveys. We used the available HST and JWST photometry to perform a SED fitting in the sample to determine their physical properties. We used the BAGPIPES code and assumed a delayed exponential model for the star formation history. We used the NIRSpec spectra from prism or grating configurations to estimate Balmer luminosities and then constrained $\xi_{ion}$ values after dust correction. We find a mean value of 10$^{25.23}$Hz erg$^{-1}$ for $\xi_{ion}$ in the sample with an observed scatter of 0.42dex. We find an increase in the median values of $\xi_{ion}$ which confirms the redshift evolution of $\xi_{ion}$ found in other works. Regarding the relation with physical properties, we find a decrease of $\xi_{ion}$ with increasing stellar mass, indicating that low-mass galaxies are efficient producers of ionizing photons. We also find an increase of $\xi_{ion}$ with increasing specific star formation rate (sSFR) and increasing UV absolute magnitude, which indicates that faint galaxies and with high sSFR are also efficient producers. We also investigated the relation of $\xi_{ion}$ with the EW([OIII]$\lambda$5007) and find that galaxies with the higher EW([OIII]) are the more efficient producers of ionizing photons. Similarly, we find that galaxies with higher O32 ratios and lower gas-phase metallicities (based on the R23 calibration) show higher $\xi_{ion}$ values.

Similarities in the non-mass dependent isotopic composition of refractory elements with the bulk silicate Earth suggest that both the Earth and the Moon formed from the same material reservoir. On the other hand, the Moon's volatile depletion and isotopic composition of moderately volatile elements points to a global devolatilization processes, most likely during a magma ocean phase of the Moon. Here, we investigate the devolatilisation of the molten Moon due to a tidally-assisted hydrodynamic escape with a focus on the dynamics of the evaporated gas. Unlike the 1D steady-state approach of Charnoz et al. (2021), we use 2D time-dependent hydrodynamic simulations carried out with the FARGOCA code modified to take into account the magma ocean as a gas source. Near the Earth's Roche limit, where the proto-Moon likely formed, evaporated gases from the lunar magma ocean form a circum-Earth disk of volatiles, with less than 30% of material being re-accreted by the Moon. We find that the measured depletion of K and Na on the Moon can be achieved if the lunar magma-ocean had a surface temperature of about 1800-2000 K. After about 1000 years, a thermal boundary layer or a flotation crust forms a lid that inhibits volatile escape. Mapping the volatile velocity field reveals varying trends in the longitudes of volatile reaccretion on the Moon's surface: material is predominantly re-accreted on the trailing side when the Moon-Earth distance exceeds 3.5 Earth radii, suggesting a dichotomy in volatile abundances between the leading and trailing sides of the Moon. This dichotomy may provide insights on the tidal conditions of the early molten Earth. In conclusion, tidally-driven atmospheric escape effectively devolatilizes the Moon, matching the measured abundances of Na and K on timescales compatible with the formation of a thermal boundary layer or an anorthite flotation crust.

Solar type V radio bursts are associated with type III bursts. Several processes have been proposed to interpret the association, electron distribution, and emission. We present the observation of a unique type V event observed by e-CALLISTO on 7 May 2021. The type V radio emission follows a group of U bursts. Unlike the unpolarized U bursts, the type V burst is circularly polarized, leaving room for a different emission process. Its starting edge drifts to higher frequency four times slower than the descending branch of the associated U burst. The type V processes seem to be ruled by electrons of lower energy. The observations conform to a coherent scenario where a dense electron beam drives the two-stream instability (causing type III emission) and, in the nonlinear stage, becomes unstable to another instability, previously known as the electron firehose instability (EFI). The secondary instability scatters some beam electrons into velocities perpendicular to the magnetic field and produces, after particle loss, a trapped distribution prone to electron cyclotron masering (ECM). A reduction in beaming and the formation of an isotropic halo are predicted for electron beams continuing to interplanetary space, possibly observable by Parker Solar Probe and Solar Orbiter.

Relativistic pair beams produced in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to generate a detectable GeV-scale electromagnetic cascade, yet this cascade is absent in the observed spectra of hard-spectrum TeV emitting blazars. This suppression is often attributed to weak intergalactic magnetic fields (IGMF) deflecting electron-positron pairs out of the line of sight. Alternatively, it has been proposed that beam-plasma instabilities could drain the energy of the beam before they produce the secondary cascades. Recent studies suggest that the modification of beam distribution due to these instabilities is primarily driven by particle scattering, rather than energy loss. In this paper, we quantitatively assess, for the blazar 1ES 0229+200, the arrival time of secondary gamma rays at Earth from the beam scattering by the electrostatic instability. We first computed the production rates of electron-positron pairs at various distances using the Monte Carlo simulation CRPropa. We then simulated the feedback of the plasma instability on the beam, incorporating production rates and inverse-Compton cooling, to determine the steady-state distribution function. Our findings reveal that the time delay of the GeV secondary cascade arrival due to instability broadening is on the order of a few months. This delay is insufficient to account for the missing cascade emission in blazar spectra, suggesting that plasma instabilities do not significantly affect IGMF constraints.

To date, the most widespread scenario is that the Earth originated without water and was brought to the planet mainly due to impacts by wet asteroids coming from further out in space. However, many uncertainties remain regarding the exact processes that supply water to inner terrestrial planets. This article explores a new mechanism that would allow water to be efficiently transported to planets without impacts. We propose that primordial asteroids were icy and that when the ice sublimated, it formed a gaseous disk that could then reach planets and deliver water. We have developed a new model that follows the sublimation of asteroids and evolves the subsequent gas disk using a viscous diffusion code. We can then quantify the amount of water that can be accreted onto each planet in a self-consistent manner. We find that this new disk-delivery mechanism can explain the water content on Earth as well as on other planets. Our model shows most of the water being delivered between 20 and 30 Myr after the birth of the Sun. Our scenario implies the presence of a gaseous water disk with substantial mass for 100s Myr, which could be one of the key tracers of this mechanism. We show that such a watery disk could be detected in young exo-asteroid belts with ALMA. We propose that viscous water transport is inevitable and more generic than the impact scenario. We also suggest it is a universal process that may also occur in extrasolar systems. The conditions required for this scenario to unfold are indeed expected to be present in most planetary systems: an opaque proto-planetary disk that is initially cold enough for ice to form in the exo-asteroid belt region, followed by a natural outward-moving snow line that allows this initial ice to sublimate after the dissipation of the primordial disk, creating a viscous secondary gas disk and leading to the accretion of water onto the exoplanets.

Context: The metal-rich bulge globular cluster NGC6388 shows a blue horizontal branch (HB). Helium (He) enrichment, which is correlated with changes in other light elements, might explain this feature. The hot HB stars in the metal-poor globular clusters NGC6397 and NGC6752, instead, show high abundances of heavy elements caused by radiative levitation. Aims: I want to use the abundances of cool blue HB stars in NGC6388 to look for He-enrichment. To exclude effects of radiative levitation for NGC6388 and to investigate the abundance changes caused by radiative levitation, I analysed the blue HB stars in NGC6397 and NGC6752. Methods: I determined effective temperatures and surface gravities from UV-optical photometry and high-resolution spectra together with LTE model spectra. The results were used together with equivalent widths by the GALA program, to provide consistent atmospheric parameters and abundances. Results: For NGC6397 and NGC6752, only moderately hot HB stars were suitable for analysis with GALA. When including literature data, a large scatter is seen at the onset of radiative levitation, followed by increasing abundances up to about 13500 K (Si, Fe), then turning to a plateau (Si) and a forking (Fe) for higher temperatures. NGC6388-4113 shows variations in radial velocity, which may indicate binarity. The metal abundances of the remaining three blue HB stars are consistent with the products of hot hydrogen burning. The data were too noisy to determine He abundances directly. Conclusions: The presence of hot hydrogen burning products in the blue HB stars in NGC6388 could indicate He enrichment. The abundance variations with temperature in moderately hot HB stars in NGC6397 and NGC6752 suggest an influence of parameters beyond rotation and effective temperature.

Ultralight bosonic wave dark matter (DM) is preponderantly contesting the conventional cold DM paradigm in predicting diverse and rich phenomena on small scales. For a DM halo made of ultralight bosons, the wave interference naturally induces slow de Broglie time-scale fluctuations of the gravitational potential. In this paper, we first derive an estimation for the effect of a time-varying gravitational potential on photon propagation. Our numerical simulations suggest that the time-varying potential of a $10^{11}M_{\odot}$ halo composed of $10^{-22}\,\mathrm{eV}$ bosons would stretch or compress a time series signal by a factor of $10^{-10}$. Here, we propose that, due to the precise measurements of their arrival times, lensed repeating fast radio bursts (FRBs) have the potential to effectively validate temporal variations in gravitational potential by monitoring their images over a period of approximately $\mathcal{O}(1)$ years. With rapidly growing FRB observations, this method would serve as a promising method to directly probe the wave nature of galactic DM halos.

Recent results from the IceCube detector and their phenomenological interpretation suggest that the corona of nearby X-ray luminous Seyfert galaxies can produce $\sim 1-10\,$TeV neutrinos via photo-hadronic interactions. We investigate in detail the physics of stochastic acceleration in such environments and examine under which conditions one can explain the inferred proton spectrum. To do so, we borrow recent findings on particle acceleration in turbulence and pay particular attention to the transport equation, notably for what concerns transport in momentum space, turbulent transport outside of the corona and advection through the corona. We first remark that the spectra obtained are highly sensitive to the value of the acceleration rate, e.g., to the Alfv\'enic velocity. Then we examine three prototype scenarios, one describing turbulent acceleration in the test-particle picture, one in which particles are pre-accelerated by turbulence and further energized by shear acceleration, and one in which we consider the effect of particle backreaction on the turbulence (damping), which self-regulates the acceleration process. We show that it is possible to obtain satisfactory fits to the inferred proton spectrum in all three cases, but stress that in the first two, the energy content in supra-thermal protons has to be fixed in an ad-hoc manner to match the inferred spectrum, at an energy density close to that contained in the turbulence. Interestingly, self-regulated acceleration by turbulence damping naturally brings the suprathermal particle energy content close to that of the turbulence and allows to reproduce the inferred flux level without additional fine tuning. We suggest that, given the strong sensitivity of the maximal proton energy to the acceleration rate, any variation of that quantity in the corona could affect, and in fact set the slope of the high-energy proton spectrum.

Wind dynamics play a pivotal role in governing transport processes within planetary atmospheres, influencing atmospheric chemistry, cloud formation, and the overall energy budget. Understanding the strength and patterns of winds is crucial for comprehensive insights into the physics of ultra-hot Jupiter atmospheres. Current research has proposed two contrasting mechanisms that limit wind speeds in these atmospheres, each predicting a different scaling of wind speed with planet temperature. However, the sparse nature of existing observations hinders the determination of population trends and the validation of these proposed mechanisms. This study focuses on unraveling the wind dynamics and the chemical composition in the atmosphere of the ultra-hot Jupiter TOI-1518 b. Two transit observations using the high-resolution (R{\lambda} = 85 000), optical (spectral coverage between 490 and 920 nm) spectrograph MAROON-X were obtained and analyzed to explore the chemical composition and wind dynamics using the cross-correlation techniques, global circulating models, and atmospheric retrieval. We report the detection of 14 species in the atmosphere of TOI-1518 b through cross-correlation analysis. Additionally, we measure the time-varying cross-correlation trails for 6 different species, compare them with predictions from General Circulation Models (GCM) and conclude that a strong drag is present in TOI-1518b's atmosphere. The ionized species require stronger drags than neutral species, likely due to the increased magnetic effects in the upper atmosphere. Furthermore, we detect vanadium oxide (VO) using the most up-to-date line list. This result is promising in detecting VO in other systems where inaccuracies in previous line lists have hindered detection. We use a retrieval analysis to further characterize the abundances of the different species detected.

We present the discovery of the fourth persistent radio source (PRS) associated with a fast radio burst (FRB). Following previous indications of a candidate PRS associated with FRB20240114A, we performed deep VLBA observations at 5 GHz to test the presence of a compact radio source within the uncertainty position of this FRB ($\pm$200 mas). We detect a component $\sim$50 mas northwards the nominal position provided by the PRECISE collaboration. The corresponding radio luminosity, together with the Faraday rotation measure provided by previous observations of the FRB, locate this PRS in the expected region of the $L$ vs |RM| relation for the nebular model, further supporting it. The comparison of the measured flux density with the respect to the values collected at lower frequency by previous studies, indicates a steepening of the radio spectrum in the 1-3 GHz range and the presence of a possible synchrotron peak at $\sim$1 GHz. Optical observations performed with the LBT could reveal that the FRB and its PRS lie at $\sim$1 kpc from the centre of the host galaxy, which is a dwarf sub-solar metallicity starburst galaxy with SFR $\sim 1 M_\odot\;\mathrm{yr^{-1}}$ and stellar mass $M\sim10^8 M_\odot$.

The kinetics of the reactions of nitrogen dioxide, NO$_2$, with atomic oxygen and atomic carbon in their ground triplet states ($^3$P) have been studied at room temperature and below using a supersonic flow (Laval nozzle) reactor. O($^3$P) and C($^3$P) atoms (hereafter O and C respectively) were created in-situ by the pulsed laser photolysis of the precursor molecules NO$_2$ at 355 nm and CBr$_4$ at 266 nm respectively. While the progress of the O + NO$_2$ reaction was followed by detecting O atoms by a chemiluminescent tracer method, progress of the C + NO$_2$ reaction was followed by detecting C atoms directly by vacuum ultra violet laser induced fluorescence at 116 nm. The measured rate constants for the O + NO$_2$ reaction are found to be in excellent agreement with earlier work at higher temperatures and extend the available kinetic data for this process down to 50 K. The present work represents the first kinetics study of the C + NO$_2$ reaction. Although both reactions display rate constants that increase as the temperature falls, a more substantial rate increase is observed for the O + NO$_2$ reaction. The effects of these reactions on the simulated abundances of interstellar NO$_2$ and related compounds were tested using a gas-grain model of the dense interstellar medium, employing expressions for the rate constants of the form, $k(T) = \alpha(T/300)^\beta$, with $\alpha = 1 \times 10^{-11}$ cm$^3$ s$^{-1}$ and $\beta = -0.65$ for the O + NO$_2$ reaction and $\alpha = 2 \times 10^{-10}$ cm$^3$ s$^{-1}$ and $\beta = -0.11$ for the C + NO$_2$ reaction. Although these simulations predict that gas-phase NO$_2$ abundances are low in dense interstellar clouds, NO$_2$ abundances on interstellar dust grains are predicted to reach reasonably high levels, indicating the potential for detection of this species in warmer regions.

We studied the multiwavelength properties of NGC 3521, the Milky Way galaxy-twin, from UV- to radio, exploring the data from GALEX for UV-, SDSS for optical, 2MASS, WISE, MIPS (Spitzer) and PACS, SPIRE (Herschel) for IR-, and NRAO VLA for radio ranges. To obtain the spectral energy distribution (SED), we exploited the CIGALE software and constructed SEDs without (model A) and with (model B) AGN module. The type of nuclear activity of NGC 3521 is confirmed as the LINER. We also present the results of the photometric data processing. Exploring the ZTF observations in 2018-2024, we found, for the first time, a weak photometric variability of the nuclear activity, where the correlation between g-r color indices and g-magnitude for long-term timescale shows a BWB trend (bluer-when-brighter) with a Pearson coefficient r(g-r)=0.56, which is a medium correlation. To detect the variability of NGC 3521 during the day (IDV), we provided observations using a Zeiss-600 telescope with an aperture size of 8" at the Terskol observatory. The data obtained in the R-filter with an exposure of 90 sec for three hours on Feb 11, 2022, serve in favor of a trend towards an increase in brightness with the amplitude of variability of 0.04 +- 0.001 mag. According to the results of the simulations, the best fit to the observed SED is provided by model A, which considers the contribution to the radiation from all galaxy components, assuming that the galaxy nucleus is inactive. Within this model, we derived the stellar mass M$_{star}$ = 2.13 * 10$^{10} M_{Sun}$, the dust mass M$_{dust}$ = 8.45 * 10$^{7} M_{Sun}$, and the star formation rate SFR = 1.76 $M_{Sun}$ * yr$^{-1}$ with $\chi^{2}$/d.o.f = 1.8. Also, based on the HIPASS radio data, we estimated the mass of neutral hydrogen to be M$_{HI}$ = 1.3 * 10$^{10} M_{Sun}$, which is an order of magnitude greater than the mass of the stellar component.

Fast Radio Bursts (FRBs) are extragalactic millisecond-duration radio transients whose nature remains unknown. The advent of numerous facilities conducting dedicated FRB searches has dramatically revolutionised the field: hundreds of new bursts have been detected, and some are now known to repeat. Using interferometry, it is now possible to localise FRBs to their host galaxies, opening up new avenues for using FRBs as astrophysical probes. One promising application is studying gravitationally lensed FRBs. This review outlines the requirements for identifying a lensed FRB, taking into account their propagation effects and the importance of capturing the amplitude and phase of the signal. It also explores the different lens masses that could be probed with FRBs throughout the duration of an FRB survey, from stellar masses to individual galaxies. This highlights the unique cosmological applications of gravitationally lensed FRBs, including measurements of the Hubble constant and the compact object content of dark matter. Finally, we discuss future radio interferometers and the prospects for finding gravitationally lensed FRBs.

Jupiter Trojans preserve primitive formation characteristics due to their collisionless stable orbits. Determination of their shapes and size-frequency distribution constrains the collisional evolution of their parent population which also originated the Kuiper Belt. We started a program to find precise sizes/shapes for Trojans, combining stellar occultations and DAMIT 3D shape models. We report results for Diomedes, by fitting its dimensionless 3D model to 3 chords of a stellar occultation observed in 2020, using iterative $\chi^{2}$ procedures. The pole coordinates, rotation period, volume-equivalent radius and geometric albedo were: $\lambda$ = 153.73$^{o}$ $\pm$ 2.5$^{o}$, $\beta$ = 12.69$^{o}$ $\pm$ 2.6$^{o}$, $P$ = 24.4984 $\pm$ 0.0002 h, $R_{eq}$ = 59.4 $\pm$ 0.3 km and $p_{V}$ = 0.030 $\pm$ 0.004. A precise position was obtained too.

During 2016 December the blazar CTA 102 underwent an unprecedented outburst thus becoming the brightest blazar observed up to date. We present some results from the intra-night monitoring of the blazar in the BVRI bands in three consecutive nights during the outburst.

We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 (1.3 mm) observations of dense cores in three massive molecular clouds within the Central Molecular Zone (CMZ) of the Milky Way, including the Dust Ridge cloud e, Sgr C, and the 20 km s-1 cloud, at a spatial resolution of 2000 au. Among the 834 cores identified from the 1.3 mm continuum, we constrain temperatures and linewidths of 253 cores using local thermodynamic equilibrium (LTE) methods to fit the H2CO and/or CH3CN spectra. We determine their masses using the 1.3 mm dust continuum and derived temperatures, and then evaluate their virial parameters using the H2CO and/or CH3CN linewidths and construct the core mass functions (CMFs). We find that the contribution of external pressure is crucial for the virial equilibrium of the dense cores in the three clouds, which contrasts with the environment in the Galactic disk where dense cores are already bound even without the contribution of external pressure. We also find that the CMFs show a Salpeter-like slope in the high-mass (>~3-6 Msun) end, a change from previous works with our new temperature estimates. Combined with the possible top-heavy initial mass functions (IMFs) in the CMZ, our result suggests that gas accretion and further fragmentation may play important roles in transforming the CMF to the IMF.

The majority of the baryonic matter in the universe is in the form of astrophysical plasmas. The mass of the hot X-ray emitting gas in a cluster of galaxies has more mass than the galaxies in the cluster. With the launch of the XRISM microcalorimeter mission, space-based X-ray observations will achieve a record spectral resolving power of $R\equiv E/\Delta E \sim 1200$. With this resolving power, emission features associated with fine-structure energy levels of some species will be resolved, sometimes for the first time. The plasma code, CLOUDY, was not originally designed for high-resolution X-ray spectroscopy and throughout its history did not resolve fine-structure components of Lyman lines. Here we expand CLOUDY to resolve these fine-structure energy levels and obtain predicted X-ray spectra that match the resolution of new microcalorimeter observations. We show how the Lyman lines can be used as column density indicators and examine their sensitivity to external radiation fields and turbulence.

This chapter reviews the three-dimensional structure, age, kinematics, and chemistry of the Milky Way (MW) region within ~2 kpc from its center (hereafter referred to as the 'bulge') from an observational perspective. While not exhaustive in citations, this review provides historical context and discusses the main controversies and limitations in the current consensus. The nuclear bulge region, within $\sim$200 pc from the Galactic center, has been excluded from this review. This very complex region, hosting dense molecular clouds and active star formation, would deserve a dedicated paper.

The internal structure of Jupiter is constrained by the precise gravity field measurements by NASA's Juno mission, atmospheric data from the Galileo entry probe, and Voyager radio occultations. Not only are these observations few compared to the possible interior setups and their multiple controlling parameters, but they remain challenging to reconcile. As a complex, multidimensional problem, characterizing typical structures can help simplify the modeling process. We used NeuralCMS, a deep learning model based on the accurate concentric Maclaurin spheroid (CMS) method, coupled with a fully consistent wind model to efficiently explore a wide range of interior models without prior assumptions. We then identified those consistent with the measurements and clustered the plausible combinations of parameters controlling the interior. We determine the plausible ranges of internal structures and the dynamical contributions to Jupiter's gravity field. Four typical interior structures are identified, characterized by their envelope and core properties. This reduces the dimensionality of Jupiter's interior to only two effective parameters. Within the reduced 2D phase space, we show that the most observationally constrained structures fall within one of the key structures, but they require a higher 1 bar temperature than the observed value. We provide a robust framework for characterizing giant planet interiors with consistent wind treatment, demonstrating that for Jupiter, wind constraints strongly impact the gravity harmonics while the interior parameter distribution remains largely unchanged. Importantly, we find that Jupiter's interior can be described by two effective parameters that clearly distinguish the four characteristic structures and conclude that atmospheric measurements may not fully represent the entire envelope.

Of the 14 transiting planets that have been detected orbiting eclipsing binaries ('circumbinary planets'), none have been detected with stellar binary orbital periods shorter than 7 days, despite such binaries existing in abundance. The eccentricity-period data for stellar binaries indicates that short-period ($< 7$ day) binaries have had their orbits tidally circularized. We examine here to what extent tidal circularization and shrinkage can conceal circumbinary planets, i.e. whether planets actually exist around short-period binaries, but are not detected because their transit probabilities drop as tides shrink the binary away from the planet. We carry out a population synthesis by initializing a population of eccentric stellar binaries hosting circumbinary planets, and then circularizing and tightening the host orbits using stellar tides. To match the circumbinary transit statistics, stellar binaries must form with eccentricities $\gtrsim$ 0.2 and periods $\gtrsim$ 6 days, with circumbinary planets emplaced on exterior stable orbits before tidal circularization; moreover, tidal dissipation must be efficient enough to circularize and shrink binaries out to $\sim$6-8 days. The resultant binaries that shrink to sub-7-day periods no longer host transiting planets. However, this scenario cannot explain the formation of nearly circular, tight binaries, brought to their present sub-seven-day orbits from other processes like disk migration. Still, tidal shrinkage can introduce a bias against finding transiting circumbinary planets, and predicts a population of KIC 3853259 (AB)b analogs consisting of wide-separation, non-transiting planets orbiting tight binaries.

We present an analysis of the UV continuum slope, beta, using a sample of 733 galaxies selected from a mixture of JWST ERS/GTO/GO observational programs and with z > 4. We consider spectroscopic data obtained with the low resolution PRISM/CLEAR NIRSpec configuration. Studying the correlation of beta with M_UV we find a decreasing trend of beta = (-0.056 +- 0.017) M_UV - (3.01 +- 0.34), consistent with brighter galaxies having redder beta as found in previous works. However, analysing the trend in separate redshift bins, we find that at high redshift the relation becomes much flatter, consistent with a flat slope. Furthermore, we find that beta decreases with redshift with an evolution as beta = (-0.075 +- 0.010) z - (1.496 +- 0.056), consistent with most previous results that show a steepening of the spectra going at higher z. We then select a sample of galaxies with extremely blue slopes (beta < -2.6): such slopes are steeper than what is predicted by stellar evolution models, even for dust free, young, metal poor populations, when the contribution of nebular emission is included. We select 51 extremely blue galaxies (XBGs) and we investigate the possible physical origin of their steep slopes, comparing them to a sub-sample of redder galaxies (matched in redshift and M_UV). We find that XBGs have younger stellar populations, stronger ionization fields, lower dust attenuation, and lower but not pristine metallicity (~ 10% solar) compared to red galaxies. However, these properties alone cannot explain the extreme beta values. By using indirect inference of Lyman continuum escape, using the most recent models, we estimate escape fractions f_esc > 10% in at least 25% of XBGs, while all the red sources have smaller f_esc. A reduced nebular continuum contribution as due to either a high escape fraction or to a bursty star-formation history is likely the origin of the extremely blue slopes.

Gravitational waves (GWs) have rapidly become important cosmological probes since their first detection in 2015. As the number of detected events continues to rise, upcoming instruments like the Einstein Telescope (ET) and Cosmic Explorer (CE) will observe millions of compact binary (CB) mergers. These detections, coupled with galaxy surveys by instruments such as DESI, Euclid, and the Vera Rubin Observatory, will provide unique information on the large-scale structure of the universe by cross-correlating GWs with the distribution of galaxies which host them. In this paper, we focus on how these cross-correlations constrain the clustering bias of GWs emitted by the coalescence of binary black holes (BBH). This parameter links BBHs to the underlying dark matter distribution, hence informing us how they populate galaxies. Using a multi-tracer approach, we forecast the precision of these measurements under different survey combinations. Our results indicate that current GW detectors will have limited precision, with measurement errors as high as $\sim50\%$. However, third-generation detectors like ET, when cross-correlated with LSST data, can improve clustering bias measurements to within $2.5\%$. Furthermore, we demonstrate that these cross-correlations can enable a percent-level measurement of the magnification lensing effect on GWs. Despite this, there is a degeneracy between magnification and evolution biases, which hinders the precision of both. This degeneracy is most effectively addressed by assuming knowledge of one bias or targeting an optimal redshift range of $1 < z < 2.5$. Our analysis opens new avenues for studying the distribution of BBHs and testing the nature of gravity through large-scale structure.

The variations of oxygen abundance and ionization parameter in HII regions are usually thought to be the dominant factors that produced variations seen in observed emission line spectra. However, if and how these two quantities are physically related is hotly debated in the literature. Using emission line data of NGC 628 observed with SITELLE as part of the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), we use a suite of photoionization models to constrain the abundance and ionization parameters for over 1500 HII regions throughout its disk. We measure an anti-correlation between these two properties, consistent with expectations, although with considerable scatter. Secondary trends with dust extinction and star formation rate surface density potentially explain the large scatter observed. We raise concerns throughout regarding various modeling assumptions and their impact on the observed correlations presented in the literature.

To prepare for the upcoming Legacy Survey of Space and Time, we develop methods for quantifying the selection function of a wide-field survey as a function of all six orbital parameters and absolute magnitude. We perform a HelioLinC3D search for Centaurs in the Pan-STARRS1 detection catalog and use a synthetic debiasing population to characterize our survey's selection function. We find nine new objects, including Centaur 2010 RJ$_{226}$, among 320 real objects, along with $\sim$70,000 debiasing objects. We use the debiasing population to fit a selection function and apply the selection function to a model Centaur population with literature orbital and size distributions. We confirm the model's marginal distributions but reject its joint distribution, and estimate an intrinsic population of 21,400$^{+3,400}_{-2,800}$ Centaurs with $H_r < 13.7$. The discovery of only nine new objects in archival data verifies that the Pan-STARRS discovery pipeline had high completeness, but also shows that new linking algorithms can contribute even to traditional single-tracklet surveys. As the first systematic application of HelioLinC3D to a survey with extensive sky coverage, this project proves the viability of HelioLinC3D as a discovery algorithm for big-data wide-field surveys.

We present a statistical analysis of different astrophysical properties of a sample of galaxy pairs in cosmic voids. The sample consists of 72 galaxy pairs with projected separations and relative radial velocities rp<100 h$^{-1}$kpc, $\Delta V <$ 500 kms$^{-1}$ in the redshift range z<0.1. The different results for this pair sample are compared to those derived for matched samples configured in absolute magnitude, stellar mass and concentration residing in void wall and global averaged environments. We find that pair galaxies in voids tend to have bluer optical colors than the corresponding galaxies in wall an field, regardless of their stellar mass and concentration, which indicates a more recent formation of the bulk of stars. We also obtain larger mid--IR colors for the void paired galaxies with respect to the corresponding matched samples in the wall and in field environments. However, we find significantly larger differences for galaxies with high mass and concentration. We also notice that mid--IR color--color diagram shows void pair members consistent with the locus of star--forming galaxies, in contrast with the other environments that exhibit a bimodal behavior comprising both passive and star--forming objects. The D$_n$(4000) parameter also shows a significant younger stellar population in paired galaxies in voids. This is also reflected in the higher star formation rate values, which show a larger efficiency for void paired galaxies. We notice that the star formation efficiency is larger for void paired galaxies with high stellar mass and concentration. We also find that the efficiency of star formation associated to galaxy interactions is significantly larger in pairs residing in cosmic voids. This larger star formation activity could be associated to both the expected richer gas environment and a more gentle dynamical behavior typical of void environments.

Icy dust particles emerge in star-forming clouds and are subsequently incorporated in protoplanetary disks, where they coagulate into larger pebbles up to mm in size. In the disk midplane, ices are shielded from UV radiation, but moderate levels of disk turbulence can lift small particles to the disk surface, where they can be altered, or destroyed. Nevertheless, studies of comets and meteorites generally find that ices at least partly retained their interstellar medium (ISM) composition before being accreted onto these minor bodies. Here we model this process through hydrodynamical simulations with VSI-driven turbulence in the outer protoplanetary disk. We use the PLUTO code in a 2.5 D global accretion setup and include Lagrangian dust particles of 0.1 and 1 mm sizes. In a post-processing step, we use the RADMC3D code to generate the local UV radiation field to assess the level of ice processing of pebbles. We find that a small fraction ($\sim$17$\%$) of 100 $\mu$m size particles are frequently lifted up to $Z/R=0.2$ which can result in the loss of their pristine composition as their residence time in this layer allows for effective CO and water photodissociation. The larger 1 mm size particles remain UV-shielded in the disk midplane throughout the dynamical evolution of the disk. Our results indicate that the assembly of icy bodies via the accretion of drifting mm-size icy pebbles can explain the presence of pristine ice from the ISM, even in VSI-turbulent disks. Nevertheless, particles $\leq$ 100 $\mu$m experience efficient UV processing and may mix with unaltered icy pebbles, resulting in a less ISM-like composition in the midplane.

We investigate the impact of Mutual Coupling (MC) between antennas on the time-delay power spectrum response of the core of the SKA-Low radio telescope. Using two in-house tools - Fast Array Simulation Tool (FAST) (a fast full-wave electromagnetic solver) and OSKAR (a GPU-accelerated radio telescope simulator) - we simulate station beams and compute visibilities for various array layouts (regular, sunflower, and random). Simulations are conducted in an Epoch of Reionisation subband between 120-150~MHz, with a fine frequency resolution of 100~kHz, enabling the investigation of late delays. Our results show that MC effects significantly increase foreground leakage into longer delays, especially for regular station layouts. For 21-cm science, foreground spill-over into the 21-cm window extends beyond $k_{\parallel} \sim 2$~h$^{-1}$Mpc for all station layouts and across all $k_{\perp}$ modes, completely obscuring the detection window. We find that attempting to remove the foreground contribution from the visibilities using an approximated beam model, based on the average embedded element pattern or interpolating the embedded element patterns from a coarse channel rate of 781~kHz, results in residuals around 1% ($\sim 10^{11}~\mathrm{mK}^2$h$^{-3}\mathrm{Mpc}^3$) which is still around 7 orders of magnitude brighter than the expected level of the EoR signal ($\sim 10^{4}~\mathrm{mK}^2$h$^{-3}\mathrm{Mpc}^3$). We also find that station beam models with at least 4-5 significant digits in the far-field pattern and high spectral resolution are needed for effective foreground removal. Our research provides critical insights into the role of MC in SKA-Low experiments and highlights the computational challenges of fully integrating array patterns that account for MC effects into processing pipelines.

Infrared studies of asymptotic giant branch (AGB) stars are critical to our understanding of the formation of cosmic dust. In this investigation, we explore the mid-to-far-infrared emission of oxygen rich AGB star RT Virginis. This optically thin dusty environment has unusual spectral features when compared to other stars in its class. To explore this enigmatic object we use the 1-D radiative transfer modeling code DUSTY. Modeled spectra are compared with observations from the Infrared Space Observatory (ISO), InfraRed Astronomical Satellite (IRAS), the Herschel Space Observatory and a host of other sources to determine the properties of RT Vir's circumstellar material. Our models suggest a set of two distant and cool dust shells at low optical depths (tauV,inner = 0.16, tauV,outer = 0.06), with inner dust temperatures: T1 = 330K, T3 = 94K. Overall, these dust shells exhibit a chemical composition consistent with dust typically found around O-rich AGB stars. However, the distribution of materials differs significantly. The inner shell consists of a mixture of silicates, Al2O3, FeO, and Fe, while the outer shell primarily contains crystalline Al2O3 polymorphs. This chemical change is indicative of two distinct epochs of dust formation around RT Vir. These changes in dust composition are driven by either changes in the pressure-temperature conditions around the star, or by a decrease in the C/O ratio due to hot-bottom burning.

We use Hubble Space Telescope imaging to study the globular cluster system of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. We select globular cluster candidates through a combination of size and color, while simultaneously rejecting contamination from background galaxies that would be unresolved in ground-based imaging. Our sample of globular cluster candidates is essentially complete down to a limiting magnitude of F814W=24.0, approximately 90% down the globular cluster luminosity function. We estimate a total globular cluster population for VCC 615 of $N_{\rm GC}=25.1^{+6.5}_{-5.4}$, resulting in a specific frequency of $S_N=55.5^{+14.5}_{-12.0}$, quite high compared to normal galaxies of similar luminosity, but consistent with the large specific frequencies found in some other UDGs. The abundant cluster population suggests the galaxy is enshrouded by a massive dark halo, consistent with previous dynamical mass estimates using globular cluster kinematics. While the peak of the globular cluster luminosity function appears slightly brighter than expected (by approximately 0.3-0.5 mag), this difference is comparable to the 0.3 mag uncertainty in the measurement, and we see no sign of an extremely luminous population of clusters similar to those detected in the UDGs NGC1054-DF2 and -DF4. However, we do find a relatively high fraction ($32^{+5}_{-4}$%) of large clusters with half-light radii greater than 9 pc. The galaxy's offset nucleus appears photometrically distinct from the globular clusters, and is more akin to ultracompact dwarfs (UCDs) in Virgo. Over time, VCC 615's already diffuse stellar body may be further stripped by cluster tides, leaving the nucleus intact to form a new Virgo UCD.

We present a solvable scenario for 3D reconnection in a sheared magnetic field. We consider a localized external force that is applied slowly and then maintained, generating an Alfv\'{e}nic perturbation that spreads along the field lines. Separation of the sheared field lines causes the scale of the perturbation across the field to decrease, enabling magnetic diffusion to be enhanced. For a fusion-motivated equilibrium with exponential field-line separation, we find a reconnection timescale proportional to $S/\ln S$ under magnetohydrodynamics (MHD) and to $S^{1/3}$ for semi-collisional electron-only reconnection, where $S$ is the Lundquist number of the perturbed flux tube. We generalize these results to arbitrary magnetic geometries, showing that the latter is geometry-independent. Interestingly, we find that slower field-line separation yields an increased reconnection rate in MHD.

We apply an Internal Robustness (iR) analysis to the recently released Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillations dataset. This approach examines combinations of data subsets through a fully Bayesian model comparison, aiming to identify potential outliers, subsets possibly influenced by systematic errors, or hints of new physics. Using this approach, we identify three data points at $z= 0.295,\,0.51,\,0.71$ as potential outliers. Excluding these points improves the internal robustness of the dataset by minimizing statistical anomalies and enables the recovery of $\Lambda$CDM predictions with a best-fit value of $w_0 = -1.050 \pm 0.128$ and $w_a = 0.208 \pm 0.546$. These results raise the intriguing question of whether the identified outliers signal the presence of systematics or point towards new physics.

The contact phase represents a crossroad in the evolution of massive binary stars. Depending on the internal physics, the predicted end products can vary greatly including various exotic objects such as Be stars, magnetic massive stars, LBVs and gravitational wave sources. This phase also offers a unique observational laboratory to study binary interaction physics. Here, I review the current state of the field of massive contact binary observations. I summarize the techniques available to identify and characterize these systems as well as the limitations of each and the potential biases that they introduce. I present the sample of known confirmed systems and what the bulk statistics can tell us about their formation and evolution. Next I discuss the challenges that these systems pose from a characterization point of view and how we can overcome these. Finally I discuss the future direction of the field on the observational side.

The number of strong lensing systems will soon increase by orders of magnitude thanks to sensitive, wide-field optical and infrared imaging surveys such as Euclid, Rubin-LSST, and Roman. A dramatic increase in strong lenses will also occur at radio wavelengths. The 2000-antenna Deep Synoptic Array (DSA-2000) will detect over $10^9$ continuum sources in the Northern Hemisphere with a high mean redshift ($\langle z_s \rangle \approx2$) and the Square Kilometer Array (SKA) will observe a large sample of extragalactic sources in the South with sub-arcsecond resolution. We forecast lensing rates, finding that the DSA-2000 will discover $\mathcal{O}(10^5)$ strongly lensed systems, many of which will be galaxy group and cluster lenses. We propose strategies for strong lensing discovery in the limit where the Einstein radii are comparable to the PSF angular scale, taking advantage of modern computer vision techniques and multi-survey data. We also forecast synergies with optical and infrared surveys, which will provide redshifts as well as multiwavelength information about the lens systems. Finally, we describe applications of radio strong lensing systems, including time-delay cosmography with transient and variable sources. We find that $\sim$100 time-variable flat-spectrum AGN discovered by the DSA-2000 could be used to constrain $H_0$ at the percent level with the appropriate follow-up.

Type Ia supernovae (SNe Ia) are runaway thermonuclear explosions in white dwarfs that result in the disruption of the white dwarf star, and possibly its nearby stellar companion. SNe Ia occur over an immense range of stellar population age and host galaxy environments, and play a critical role in the nucleosynthesis of intermediate-mass and iron-group elements, primarily the production of nickel, iron, cobalt, chromium, and manganese. Though the nature of their progenitors is still not well-understood, SNe Ia are unique among stellar explosions in that the majority of them exhibit a systematic lightcurve relation: more luminous supernovae dim more slowly over time than less luminous supernovae in optical light (intrinsically brighter SNe Ia have broader lightcurves). This feature, unique to SNe Ia, is rather remarkable and allows their peak luminosities to be determined with fairly high accuracy out to cosmological distances via measurement of their lightcurve decline. Further, studying SNe Ia gives us important insights into binary star evolution physics, since it is widely agreed that the progenitors of SNe Ia are binary (possibly multiple) star systems. In this review, we give a current update on the different proposed Type Ia supernova progenitors, including descriptions of possible binary star configurations, and their explosion mechanisms, from a theoretical perspective. We additionally give a brief overview of the historical (focusing on the more recent) observational work that has helped the astronomical community to understand the nature of the most important distance indicators in cosmology.

We present detailed evolutionary simulations of wide binary systems with high-mass ($8-20\,M_{\odot}$) donor stars and a $1.4\,M_{\odot}$ neutron star. Mass transfer in such binaries is dynamically unstable and common envelope (CE) evolution is followed. We use a recently developed prescription to deal with CE evolution and consider various CE ejection efficiencies varying in the range of $0.1-3.0$. We focus on the evolutionary consequences of the binaries survived CE evolution. We demonstrate that it is possible for the binaries to enter a CE decoupling phase (CEDP) when the donor stars are partially stripped leaving a hydrogen envelope of $\lesssim1.0-4.0\,M_\odot$ after CE evolution. This phase is expected to last $\sim 10^4-10^5\,\rm yr$, during which mass transfer occurs stably via Roche lobe overflow with super-Eddington rates. Identification of some X-ray binaries in a CEDP is important for the understanding of the physics of CE evolution itself, the origin of ultraluminous X-ray sources, and the recycling process of accreting pulsars. Also, we discuss the formation of double neutron stars and the occurrence of ultra-stripped supernovae according to the results from our simulations. On the whole, the properties of post-CE binaries are sensitive to the options of CE ejection efficiencies.

During their formation, galaxies are subject to tidal forces, which create correlations between their shapes and the large-scale structure of the Universe, known as intrinsic alignment. This alignment is a contamination for cosmic-shear measurements as one needs to disentangle correlations induced by external lensing effects from those intrinsically present in galaxies. We constrain the amplitude of intrinsic alignment and test models by making use of the overlap between the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS) covering $3500 \, \mathrm{deg}^2$, and spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS/eBOSS). By comparing our results to measurements from other lensing surveys on the same spectroscopic tracers, we can test the reliability of these estimates and verify they are not survey dependent. We measure projected correlation functions between positions and ellipticities, which we model with perturbation theory to constrain the commonly used non-linear alignment model and its higher-order expansion. Using the non-linear alignment model, we obtain a $13\sigma$ detection with CMASS galaxies, a $3\sigma$ detection with LRGs, and a detection compatible with the null hypothesis for ELGs. We test the tidal alignment and tidal torque model, a higher-order alignment model, which we find to be in good agreement with the non-linear alignment prediction and for which we can constrain the second-order parameters. We show a strong scaling of our intrinsic alignment amplitude with luminosity. We demonstrate that the UNIONS sample is robust against systematic contributions, particularly concerning PSF biases. We reached a reasonable agreement when comparing our measurements to other lensing samples for the same spectroscopic samples. We take this agreement as an indication that direct measurements of intrinsic alignment are mature for stage IV priors.

We studied bent radio sources within X-ray galaxy groups in the COSMOS and XMM-LSS fields, using radio data from the MeerKAT International GHz Tiered Extragalactic Explorations data release 1 (MIGHTEE-DR1) at 1.2-1.3 GHz (angular resolutions of 8.9" and 5"; ~ 3.5 and 5.5 uJy/beam). Bent radio active galactic nuclei (AGN) were identified via visual inspection. Our analysis included 19 bent radio AGN in the COSMOS field and 17 in the XMM-LSS field which lie within X-ray galaxy groups (2x10^13 >= M200c/Msun = 3x10^14). We investigated the relationship between their bending angle (BA) - the angle formed by the jets or lobes of two-sided radio sources associated with AGN - and properties of their host galaxies and large-scale environment probed by the X-ray galaxy groups. Our key findings are: a) In the XMM-LSS field, we observed a strong correlation between the linear projected size of the bent AGN, the group halo mass, and the projected distance from the group centre. This trend, consistent with previous studies, was not detected in the COSMOS sample. b) The BA is a function of environmental density, with the type of medium playing a significant role. Additionally, at z <= 0.5 we found a higher number of bent sources (BA <= 160deg) compared to higher redshifts (z ~ 1), by a factor of >1.5. This trend aligns with magnetohydrodynamic simulations, which suggest that denser environments and longer interaction times at lower redshifts contribute to this effect. Comparison with the literature suggests that jet bending in galaxy groups within the redshift range 0.1 < z < 1.2 is primarily driven by ram pressure exerted on the jets, which occurs during quiescent phases of AGN activity. This study underscores the role of environmental interactions in shaping the morphology of radio AGN within galaxy groups, providing insights into the interplay between large-scale structure and AGN physics.

A century or less separates the thermonuclear-powered eruptions of recurrent novae in the hydrogen-rich envelopes of massive white dwarfs. The colliding ejecta of successive recurrent nova events are predicted to always generate very large (tens of parsecs) super-remnants; only two examples are currently known. T CrB offers an excellent opportunity to test this prediction. As it will almost certainly undergo its next, once-in ~80-year recurrent nova event between 2024 and 2026, we carried out very deep narrowband and continuum imaging to search for the predicted, piled-up ejecta of the past millenia. While nothing is detected in continuum or narrowband [OIII] images, a ~30-parsec-diameter, faint nebulosity surrounding T CrB is clearly present in deep Halpha, [NII] and [SII] narrowband Condor Array Telescope imagery. We predict that these newly detected nebulosities, as well as the recent ejecta that have not yet reached the super-remnant, are far too optically-thin to capture all but a tiny fraction of the photons emitted by RN flashes. We thus predict that fluorescent light echoes will NOT be detectable following the imminent nova flash of T CrB. Dust may be released by the T CrB red giant wind in pre-eruption outbursts, but we have no reliable estimates of its quantity or geometrical distribution. While we cannot predict the morphology or intensity of dust-induced continuum light echoes following the coming flash, we encourage multi-epoch Hubble Space Telescope optical imaging as well as James Webb Space Telescope infrared imaging of T CrB during the year after it erupts.

The origin of supermassive black holes (SMBHs) is a key open question for contemporary astrophysics and cosmology. Here we review the features of a cosmological model of SMBH formation from Pop III.1 seeds, i.e., remnants of metal-free stars forming in locally-isolated minihalos, where energy injection from dark matter particle annihilation alters the structure of the protostar allowing growth to supermassive scales (Banik et al. 2019; Singh et al. 2023; Cammelli et al. 2024). The Pop III.1 model explains the paucity of intermediate-mass black holes (IMBHs) via a characteristic SMBH seed mass of $\sim10^5\:M_\odot$ that is set by the baryonic content of minihalos. Ionization feedback from supermassive Pop III.1 stars sets the cosmic number density of SMBHs to be $n_{\rm SMBH}\lesssim 0.2\:{\rm Mpc}^{-3}$. The model then predicts that all SMBHs form by $z\sim20$ with a spatial distribution that is initially unclustered. SMBHs at high redshifts $z\gtrsim7$ should all be single objects, with SMBH binaries and higher order multiples emerging only at lower redshifts. We also discuss the implications of this model for SMBH host galaxy properties, occupation fractions, gravitational wave emission, cosmic reionization, and the nature of dark matter. These predictions are compared to latest observational results, especially from HST, JWST and pulsar timing array observations.

Motivated by the scarcity of proper labels in an astrophysical application, we have developed a novel technique, called Selfish Evolution, which allows for the detection and correction of corrupted labels in a weakly supervised fashion. Unlike methods based on early stopping, we let the model train on the noisy dataset. Only then do we intervene and allow the model to overfit to individual samples. The ``evolution'' of the model during this process reveals patterns with enough information about the noisiness of the label, as well as its correct version. We train a secondary network on these spatiotemporal ``evolution cubes'' to correct potentially corrupted labels. We incorporate the technique in a closed-loop fashion, allowing for automatic convergence towards a mostly clean dataset, without presumptions about the state of the network in which we intervene. We evaluate on the main task of the Supernova-hunting dataset but also demonstrate efficiency on the more standard MNIST dataset.

The properties of dilute neutron matter are mostly determined by the s-wave two-body (2N) interaction, while three-body (3N) interactions are suppressed by the Pauli principle. In a previous work, we showed that it can be advantageous to use the renormalization group based effective interactions with cutoffs scaled with the Fermi momentum, especially at low densities. In that case, induced 3N interactions may become important. In this work, we compute the 3N interaction induced by the similarity renormalization group flow of the s-wave 2N interaction. We work in the momentum-space hyperspherical partial wave basis and investigate its convergence properties. Then we study the effect of the induced 3N interaction on the equation of state of dilute neutron matter. We observe that the cutoff dependence of the equation of state is strongly reduced when the effect of induced 3N interaction is included.

We investigate the decay of bosonic dark matter with masses between 1 MeV and 2 TeV into Standard Model final states. We specifically focus on dark photons that kinetically mix with the Standard Model, as well as scalar dark matter models that have Yukawa couplings with the Standard Model. Using INTEGRAL and AMS-02 data, we constrain the dark matter decay lifetime into final states that include photons or positrons, setting strong constraints on the dark matter lifetime that reach 10$^{25}$ s for dark matter below 10 GeV and up to 10$^{29}$ s for dark matter above 10 GeV.

In the current review, we provide a summary of the recent progress made in the cosmological aspect of extra-dimensional Lovelock gravity. Our review covers a wide variety of particular model/matter source combinations: Einstein--Gauss--Bonnet as well as cubic Lovelock gravities with vacuum, cosmological constant, perfect fluid, spatial curvature, and some of their combinations. Our analysis suggests that it is possible to set constraints on the parameters of the above-mentioned models from the simple requirement of the existence of a smooth transition from the initial singularity to a realistic low-energy regime. Initially, anisotropic space naturally evolves into a configuration with two isotropic subspaces, and if one of these subspaces is three-dimensional and is expanding while another is contracting, we call it realistic compactification. Of course, the process is not devoid of obstacles, and in our paper, we review the results of the compactification occurrence investigation for the above-mentioned models. In particular, for vacuum and $\Lambda$-term EGB models, compactification is not suppressed (but is not the only possible outcome either) if the number of extra dimensions is $D \geqslant 2$; for vacuum cubic Lovelock gravities it is always present (however, cubic Lovelock gravity is defined only for $D \geqslant 3$ number of extra dimensions); for the EGB model with perfect fluid it is present for $D=2$ (we have not considered this model in higher dimensions yet), and in the presence of spatial curvature, the realistic stabilization of extra dimensions is always present (however, such a model is well-defined only in $D \geqslant 4$ number of extra dimensions).

Space debris presents a critical challenge for the sustainability of future space missions, emphasizing the need for robust and standardized identification methods. However, a comprehensive benchmark for rocket body classification remains absent. This paper addresses this gap by introducing the RoBo6 dataset for rocket body classification based on light curves. The dataset, derived from the Mini Mega Tortora database, includes light curves for six rocket body classes: CZ-3B, Atlas 5 Centaur, Falcon 9, H-2A, Ariane 5, and Delta 4. With 5,676 training and 1,404 test samples, it addresses data inconsistencies using resampling, normalization, and filtering techniques. Several machine learning models were evaluated, including CNN and transformer-based approaches, with Astroconformer reporting the best performance. The dataset establishes a common benchmark for future comparisons and advancements in rocket body classification tasks.

Gravitational lensing of gravitational waves (GWs) provides a unique opportunity to study cosmology and astrophysics at multiple scales. Detecting microlensing signatures, in particular, requires efficient parameter estimation methods due to the high computational cost of traditional Bayesian inference. In this paper we explore the use of deep learning, namely Conditional Variational Autoencoders (CVAE), to estimate parameters of microlensed binary black hole (simulated) waveforms. We find that our CVAE model yields accurate parameter estimation and significant computational savings compared to Bayesian methods such as bilby (up to five orders of magnitude faster inferences). Moreover, the incorporation of CVAE-generated priors in bilby reduces the average runtime of the latter in about 48% with no penalty on its accuracy. Our results suggest that a CVAE model is a promising tool for future low-latency searches of lensed signals. Further applications to actual signals and integration with advanced pipelines could help extend the capabilities of GW observatories in detecting microlensing events.

In this work, we investigate static and spherically symmetric black hole solutions in $f(R,T)$ gravity, where $R$ is the curvature scalar and $T$ is the trace of the energy-momentum tensor, coupled to nonlinear electrodynamics (NLED). To construct our solutions, we adopt a linear functional form, $f(R,T) = R + \beta T$. In the limit $\beta = 0$, the theory reduces to General Relativity (GR), recovering $f(R,T) \approx R$. We propose a power-law Lagrangian of the form $\mathcal{L} = f_0 + F + \alpha F^p$, where $\alpha =f_0= 0$ corresponds to the linear electrodynamics case. Using this setup, we derive the metric functions and determine an effective cosmological constant. Our analysis focuses on specific cases with $p = 2$, $p = 4$, and $p = 6$, where we formulate analytic expressions for the matter fields supporting these solutions in terms of the Lagrangian as a function of $F$. Additionally, we verify the regularity of the solutions and study the structure of the event horizons. Furthermore, we examine a more specific scenario by determining the free forms of the first and second derivatives $\mathcal{L}_F(r)$ and $\mathcal{L}_{FF}(r)$ of the Lagrangean of the nonlinear electromagnetic field. From these relations, we derive the general form of $\mathcal{L}_{\text{NLED}}(r)$ using consistency relations. This Lagrangian exhibits an intrinsic nonlinearity due to the influence of two constants, $\alpha$ and $\beta$. Specifically, $\alpha$ originates from the power-law term in the proposed Lagrangian, while $\beta$ arises from the assumed linear function $f(R,T)$. The interplay of these constants ensures that the nonlinearity of the Lagrangian is governed by both $\alpha$ and $\beta$, rather than $\alpha$ alone.

Calculations for electron capture rates on nuclei with atomic numbers between $Z=20$ and $Z=52$ are performed in a self-consistent finite-temperature covariant energy density functional theory within the relativistic quasiparticle random-phase approximation. Electron captures on these nuclei contribute most to reducing the electron fraction during the collapse phase of core-collapse supernovae. The rates include contributions from allowed (Gamow-Teller) and first-forbidden (FF) transitions, and it is shown that the latter become dominant at high stellar densities and temperatures. Temperature-dependent effects such as Pauli unblocking and transitions from thermally excited states are also included. The new rates are implemented in a spherically symmetric 1D simulation of the core-collapse phase. The results indicate that the increase in electron capture rates, due to inclusion of FF transitions, leads to reductions of the electron fraction at nuclear saturation density, the peak neutrino luminosity, and enclosed mass at core bounce. The new rates reaffirm that the most relevant nuclei for the deleptonization situate around the $N = 50$ and $82$ shell closures, but compared to previous simulations, nuclei are less proton rich. The new rates developed in this work are available, and will be of benefit to improve the accuracy of multi-dimensional supernova simulations.

In this paper, we study time-like geodesics around a spherically symmetric black hole in Kalb-Ramond (KR) gravity, characterized by the parameter $l$, which induces spontaneous Lorentz symmetry breaking. The geodesic equations and effective potential are derived to investigate the influence of $l$. We calculate the marginally bound orbits and innermost stable circular orbits, analyzing the parameter's impact. Periodic orbits are computed numerically and classified within the standard taxonomy, revealing significant effects of $l$ on their momentum and energy. Additionally, we explore an extreme mass ratio inspiral system under the adiabatic approximation to derive gravitational waveforms emitted by an object orbiting a supermassive black hole in KR gravity. These waveforms reflect the distinctive characteristics of periodic orbits and highlight the influence of $l$. With advancements in gravitational wave detection, these results offer insights into black holes influenced by Lorentz symmetry-breaking fields.

Dark photon is one of the promising candidates of light dark matter and could be detected by using its interaction with standard model particles via kinetic mixings. Here, we propose a feasible approach to detect the dark photons by nondestructively probing these mixing-induced quantum state transitions of atomic ensembles. Compared with the scheme by probing the mixing-induced quantum excitation of single-atom detector, the achievable detection sensitivity can be enhanced theoretically by a factor of $\sqrt{N}$ for the ensemble containing $N$ atoms. Specifically, we show that the dark photons, in both centimeter- and millimeter-wave bands, could be detected by using the artificial atomic ensemble detector, generated by surface-state electrons on liquid Helium. It is estimated that, with the detectable transition probability of $10^{-4}$, the experimental surface-state electrons (with $N = 10^8$ trapped electrons) might provide a feasible approach to search for the dark photons in $18.61-26.88$ $\mu$eV and $496.28-827.13$ $\mu$eV ranges, within about two months. The confidence level can exceed 95\% for the achievable sensitivities being $10^{-14} \sim 10^{-13}$ and $10^{-12} \sim 10^{-11}$, respectively. In principle, the proposal could also be generalized to the other atomic ensemble detectors for the detection of dark photons in different frequency bands.

Multi-messenger observations of astrophysical transients provide powerful probes of the underlying physics of the source as well as beyond the Standard Model effects. We explore transients that can occur in the vicinity of supermassive black holes at the center of galaxies, including tidal disruption events (TDEs), certain types of blazars, or even supernovae. In such environments, the dark matter (DM) density can be extremely high, resembling a dense spike or core. We study a novel effect of neutrino diffusion sustained via frequent scatterings off DM particles in these regions. We show that for transients occurring within DM spikes or cores, the DM-neutrino scattering can delay the arrival of neutrinos with respect to photons, but this also comes with a suppression of the neutrino flux and energy loss. We apply these effects to the specific example of TDEs, and demonstrate that currently unconstrained parameter space of DM-neutrino interactions can account for the sizable $O$(days) delay of the tentative high-energy neutrinos observed from some TDEs.

Recently, our group developed explicit symplectic methods for curved spacetimes that are not split into several explicitly integrable parts, but are via appropriate time transformations. Such time-transformed explicit symplectic integrators should have employed adaptive time steps in principle, but they are often difficult in practical implementations. In fact, they work well if time transformation functions cause the time-transformed Hamiltonians to have the desired splits and approach 1 or constants for sufficiently large distances. However, they do not satisfy the requirement of step-size selections in this case. Based on the step-size control technique proposed by Preto $\&$ Saha, the nonadaptive time step time-transformed explicit symplectic methods are slightly adjusted as adaptive ones. The adaptive methods have only two additional steps and a negligible increase in computational cost as compared with the nonadaptive ones. Their implementation is simple. Several dynamical simulations of particles and photons near black holes have demonstrated that the adaptive methods typically improve the efficiency of the nonadaptive methods. Because of the desirable property, the new adaptive methods are applied to investigate the chaotic dynamics of particles and photons outside the horizon in a Schwarzschild-Melvin spacetime. The new methods are widely applicable to all curved spacetimes corresponding to Hamiltonians or time-transformed Hamiltonians with the expected splits. Also application to the backwards ray-tracing method for studying the motion of photons and shadows of black holes is possible.

Continuous gravitational wave searches with terrestrial, long-baseline interferometers are hampered by long-lived, narrowband features in the power spectral density of the detector noise, known as lines. Candidate GW signals which overlap spectrally with known lines are typically vetoed. Here we demonstrate a line subtraction method based on adaptive noise cancellation, using a recursive least squares algorithm, a common approach in electrical engineering applications such as audio and biomedical signal processing. We validate the line subtraction method by combining it with a hidden Markov model (HMM), a standard continuous wave search tool, to detect an injected continuous wave signal with an unknown and randomly wandering frequency, which overlaps with the mains power line at $60 \, {\rm Hz}$ in the Laser Interferometer Gravitational Wave Observatory (LIGO). The performance of the line subtraction method is tested on an injected continuous wave signal obscured by (a) synthetic noise data with both Gaussian and non-Gaussian components, and (b) real noise data obtained from the LIGO Livingston detector. In both cases, before applying the line subtraction method the HMM does not detect the injected continuous wave signal. After applying the line subtraction method the mains power line is suppressed by 20--40 dB, and the HMM detects the underlying signal, with a time-averaged root-mean-square error in the frequency estimate of $\sim 0.05 $ Hz. The performance of the line subtraction method with respect to the characteristics of the 60 Hz line and the control parameters of the recursive least squares algorithm is quantified in terms of receiver operating characteristic curves.

$f(Q)$ and $f(T)$ gravity are based on fundamentally different geometric frameworks, yet they exhibit many similar properties. In this article, we identify two types of background-dependent and classical correspondences between these two theories of gravity. The first correspondence is rooted in their equivalence within the background of Minkowski spacetime, while the second is based on the equivalence of their equations of motion. To establish the first correspondence, we develop the tetrad-spin formulation of $f(Q)$ gravity and we derive the corresponding expression for the spin connection. Additionally, we extract the equations of motion of $f(Q)$ gravity within this tetrad-spin framework and we elucidate the relationship through an example in spherical coordinates. For the second correspondence, we derive the general affine connection for the static and spherically symmetric spacetime in $f(Q)$ gravity, and we compare its equations of motion with the ones of $f(T)$ gravity. Amongst others, our results reveal that, within our affine connection branch, $f(T)$ solutions are not simply a subset of $f(Q)$ solutions; rather, they encompass a complex solution beyond $f(Q)$ gravity.

The Torsion-Bar Antenna (TOBA) is a torsion pendulum-based gravitational detector developed to observe gravitational waves in frequencies between 1 mHz and 10 Hz. The low resonant frequency of the torsion pendulum enables observation in this frequency band on the ground. The final target of TOBA is to observe gravitational waves with a 10 m detector and expand the observation band of gravitational waves. In this paper, an overview of TOBA, including the previous prototype experiments and the current ongoing development, is presented.

The recent observation of the compact star XTE J1814-338 with a mass of $M=1.2^{+0.05}_{-0.05}~{\rm M_{\odot}}$ and a radius of $R=7^{+0.4}_{-0.4}$ km, together with the HESS J1731-347, which has a mass of $M=0.77^{+0.20}_{-0.17}~{\rm M_{\odot}}$ and a radius of $R=10.4^{+0.86}_{-0.78}$ km, they provide evidence for the possible presence of exotic matter in the core of neutron stars and significantly enhance our understanding of the equation of state for the dense nuclear matter. In the present srtudy, we investigate the possible existence of neutral anti-kaons and negative charged kaons in neutron stars by employing the Relativistic Mean Field model with first order kaonic (${K^{-}}$ and ${\bar{K^{0}}}$) condensates. To the best of our knowledge, this represents a first alternative attempt aimed to explain the bulk properties of the XTE J1814-338 object and at the same time the HESS J1731-347 object, using a mixture of kaons condensation in dense nuclear matter. In addition, we compare our analysis approach with the recent observation of PSR J0437-4715 and PSR J1231-1411 pulsars, proposing that to explain all objects simultaneously, it is essential to consider two distinct branches, each corresponding to a different composition of nuclear matter.

The present work investigates the possible range of the spectral index $n_s$ and the tensor-to-scalar ratio $r$ for a sub-class of the generalized multi-scalar field inflation, which includes a linear coupling term between the multi-scalar field potential and the canonical Lagrangian. This coupling influences the slow-roll parameters and also alters our predictions for $n_{s}$ and $r$, which directly depend on those parameters. More precisely, compared to standard multi-field inflation, the values of $n_{s}$ and $r$ decrease to levels consistent with the recent Planck+BICEP/Keck constraint. Interestingly, this validates the chaotic-type potential $V=\sum_{i} \mu_{i} \phi_{i}^{p}$, which were previously ruled out in the light of the current observations.

Cosmology and GR remain largely inaccessible to high-school teaching due to the advanced prerequisites to master these topics. Integrating them into upper secondary teaching is a significant challenge that remains unresolved. This contribution reports on an implementation study of a GR and cosmology course for upper secondary school students as part of an educational project launched during the centenary of GR and tested ever since for several years. The course aimed to expand students' knowledge to include current physics topics while highlighting their foundations in areas of classical physics such as Newtonian mechanics, electromagnetism, and waves. Targeted teaching and learning materials are focused on conceptual and qualitative understanding, while systematically combined with a mathematical treatment accessible at the upper secondary level, avoiding oversimplification. A key element is an active learning approach, incorporating activities and tasks such as engaging applications related to current research, reflective exercises, thought experiments, and hands-on tasks. The main research objective was to explore whether a conceptually deep and educationally effective GR and cosmology course could be successfully implemented for non-specialist upper secondary students. A pre-post study assessed both conceptual learning and affective outcomes, including interest, curiosity, self-concept, and perceived relevance of science. Results showed encouraging gains in both learning and motivation, with large to very large effect sizes for conceptual learning of core principles. Additionally, no or small effects of predictors such as gender were observed. We conclude that the integration of GR and cosmology into upper secondary physics teaching, in the form of courses and materials that are engaging, comprehensible, and impactful, is feasible.

The ultra high frequency emission of gravitational waves by binary systems of black holes has recently been investigated in details in the framework of new experimental ideas around resonant cavities. In this article, we consider the case of elliptic trajectories. At fixed masses and frequency, we conclude that the total amount of energy radiated by the system within the bandwidth of the detector can be significantly higher than for circular orbits. However, due to subtle experimental effects, the signal-to-noise ratio is, overall, a decreasing function of the eccentricity. Limits on the maximum distance at which a merging system of black holes can be detected derived for circular orbits are therefore not improved by considering elliptic trajectories. The article is written as pedagogically as possible so as to be accessible to the non-familiar reader.

Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long lived radioisotopes, such as 60Fe (iron) and 26Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed 60Fe/26Al ratio by {\gamma}-ray telescopes and predictions from supernova models. This discrepancy has been attributed to uncertainties in the nuclear reaction networks producing 60Fe, and one reaction in particular, the neutron-capture on 59Fe. Here we present experimental results that provide a strong constraint on this reaction. We use these results to show that the production of 60Fe in massive stars is higher than previously thought, further increasing the discrepancy between observed and predicted 60Fe/26Al ratios. The persisting discrepancy can therefore not be attributed to nuclear uncertainties, and points to issues in massive-star models.

We analyse the implications of the presence of spatial curvature in modified gravity models. As it is well known, the current standard cosmological model, the $\Lambda$CDM, is assumed to be spatially flat based on the results of many experiments. However, this statement does not necessarily hold for a modified gravity (MG) model, and this leads to couplings of the spatial curvature with the parameters of the chosen cosmological model. In this paper, we illustrate the theoretical development of how spatial curvature affects the equations of motion at linear order for scalar and tensor perturbations modes using a model-independent approach based on the formalism of the Effective Field Theory (EFT) of dark energy (DE). The results show that spatial curvature gives rise to a coupling with the scalar field perturbations and the functions parameterizing the model.

We analyse the collisionless tearing mode instability of a current sheet with a strong shear flow across the layer. The growth rate decreases with increasing shear flow, and is completely stabilized as the shear flow becomes Alfv\'enic. We also show that in the presence of strong flow shear, the tearing mode growth rate decreases with increasing background ion-to-electron temperature ratio, the opposite behaviour to the tearing mode without flow shear. We find that even a relatively small flow shear is enough to dramatically alter the scaling behaviour of the mode, because the growth rate is small compared to the shear flow across the ion scales (but large compared to shear flow across the electron scales). Our results may explain the relative absence of reconnection events in the near-Sun Alfv\'enic solar wind observed recently by NASA's Parker Solar Probe.