Sazuna/UAT_keywords huggingface dataset:
Opening the Era of Quasar-host Studies at High Redshift with JWST. We measure the host galaxy properties of five quasars with z ~ 1.6-3.5 selected from the Sloan Digital Sky Survey (SDSS) and AEGIS, which fall within the JWST/Hubble Space Telescope (HST) CEERS survey area. A point-spread function library is constructed based on stars in the full field of view of the data and used with the 2D image modeling tool galight to decompose the quasar and its host with multiband filters available for HST ACS+WFC3 and JWST NIRCAM (12 filters covering HST F606W to JWST F444W). As demonstrated, JWST provides the first capability to detect quasar hosts at z &gt; 3 and enables spatially resolved studies of the underlying stellar populations at z ~ 2 within morphological structures (spiral arms, bar) not possible with HST. Overall, we find quasar hosts to be disk-like, lack merger signatures, and have sizes generally more compact than typical star-forming galaxies at their respective stellar mass, thus in agreement with results at lower redshifts. The fortuitous face-on orientation of SDSSJ1420+5300A at z = 1.646 enables us to find higher star formation and younger ages in the central 2-4 kpc region relative to the outskirts, which may help explain the relatively compact nature of quasar hosts and pose a challenge to active galactic nucleus feedback models.

Keywords: AGN host galaxies, Active galaxies, Galaxy evolution, Quasars
Signatures of r-process Enrichment in Supernovae from Collapsars. Despite recent progress, the astrophysical channels responsible for rapid neutron capture (r-process) nucleosynthesis remain an unsettled question. Observations of the kilonova following the gravitational-wave-detected neutron star merger GW170817 established mergers as one site of the r-process, but additional sources may be needed to fully explain r-process enrichment in the universe. One intriguing possibility is that rapidly rotating massive stars undergoing core collapse launch r-process-rich outflows off the accretion disks formed from their infalling matter. In this scenario, r-process winds are one component of the supernova (SN) ejecta produced by "collapsar" explosions. We present the first systematic study of the effects of r-process enrichment on the emission from collapsar-generated SNe. We semianalytically model r-process SN emission from explosion out to late times and determine its distinguishing features. The ease with which r-process SNe can be identified depends on how effectively wind material mixes into the initially r-process-free outer layers of the ejecta. In many cases, enrichment produces a near-infrared (NIR) excess that can be detected within ~75 days of explosion. We also discuss optimal targets and observing strategies for testing the r-process collapsar theory, and find that frequent monitoring of optical and NIR emission from high-velocity SNe in the first few months after explosion offers a reasonable chance of success while respecting finite observing resources. Such early identification of r-process collapsar candidates also lays the foundation for nebular-phase spectroscopic follow-up in the NIR and mid-infrared, for example, with the James Webb Space Telescope.

Keywords: R-process, Core-collapse supernovae
First Detection of Silicon-bearing Molecules in η Car. We present ALMA band 6 observations of the luminous blue variable η Car obtained within the ALMAGAL program. We report SiO J = 5 → 4, SiS J = 12 → 11, and SiN N = 5 → 4 emission in the equatorial region of the Homunculus nebula, constituting the first detection of silicon- and sulfur-bearing molecules in the outskirts of a highly evolved, early-type massive star. The SiO, SiS, and SiN trace a clumpy equatorial ring that surrounds the central binary at a projected distance of ~2″, delineating the inner rims of the butterfly-shaped dusty region. The formation of silicon-bearing compounds is presumably related to the continuous recycling of dust due to the variable wind regime of η Car, which destroys grains and releases silicon back to the gas phase. We discuss possible formation routes for the observed species, contextualizing them within the current molecular inventory of η Car. We find that the SiO and SiS fractional abundances in localized clumps of the ring, 6.7 × 10-9 and 1.2 × 10-8, respectively, are exceptionally lower than those measured in C- and O-rich AGB stars and cool supergiants, while the higher SiN abundance, 3.6 × 10-8, evidences the nitrogen-rich chemistry of the ejecta. These abundances must be regarded as strict upper limits, since the distribution of H2 in the Homunculus is unknown. In any case, these findings shed new light on the peculiar molecular ecosystem of η Car and establish its surroundings as a new laboratory to investigate the life cycle of silicate dust in extreme astrophysical conditions.

Keywords: Molecular gas, Dust destruction, Massive stars, Luminous blue variable stars, Stellar mass loss, Astrochemistry, Circumstellar matter
Has JWST Already Falsified Dark-matter-driven Galaxy Formation?. The James Webb Space Telescope (JWST) discovered several luminous high-redshift galaxy candidates with stellar masses of M * ≳ 109 M ⊙ at photometric redshifts z phot ≳ 10, which allows to constrain galaxy and structure formation models. For example, Adams et al. identified the candidate ID 1514 with ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })={9.8}_{-0.2}^{+0.2}$ located at ${z}_{\mathrm{phot}}={9.85}_{-0.12}^{+0.18}$ and Naidu et al. found even more distant candidates labeled as GL-z11 and GL-z13 with ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })={9.4}_{-0.3}^{+0.3}$ at ${z}_{\mathrm{phot}}={10.9}_{-0.4}^{+0.5}$ and ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })={9.0}_{-0.4}^{+0.3}$ at ${z}_{\mathrm{phot}}={13.1}_{-0.7}^{+0.8}$ , respectively. Assessing the computations of the IllustrisTNG (TNG50-1 and TNG100-1) and EAGLE projects, we investigate if the stellar mass buildup as predicted by the ΛCDM paradigm is consistent with these observations assuming that the early JWST calibration is correct and that the candidates are indeed located at z ≳ 10. Galaxies formed in the ΛCDM paradigm are by more than an order of magnitude less massive in stars than the observed galaxy candidates implying that the stellar mass buildup is more efficient in the early universe than predicted by the ΛCDM models. This in turn would suggest that structure formation is more enhanced at z ≳ 10 than predicted by the ΛCDM framework. We show that different star formation histories could reduce the stellar masses of the galaxy candidates alleviating the tension. Finally, we calculate the galaxy-wide initial mass function (gwIMF) of the galaxy candidates assuming the integrated galaxy IMF theory. The gwIMF becomes top-heavy for metal-poor star-forming galaxies decreasing therewith the stellar masses compared to an invariant canonical IMF.

Keywords: Cosmology, Early universe, Galaxy formation, Initial mass function, Galaxy properties, Cold dark matter, Stellar mass functions, Galaxy mass distribution, James Webb Space Telescope, Galaxy evolution, Stellar masses, High-redshift galaxies
Optical-Radio Position Offsets Are Inversely Correlated with AGN Photometric Variability. Using photometric variability information from the new Gaia DR3 release, I show for the first time that photometric variability is inversely correlated with the prevalence of optical-radio position offsets in the active galactic nuclei (AGNs) that comprise the International Celestial Reference Frame (ICRF). While the overall prevalence of statistically significant optical-radio position offsets is 11%, objects with the largest fractional variabilities exhibit an offset prevalence of only ~2%. These highly variable objects have redder optical color and steeper optical spectral indices indicative of blazars, in which the optical and radio emission is dominated by a line-of-sight jet, and indeed nearly ~100% of the most variable objects have γ-ray emission detected by the Fermi Large Area Telescope. This result is consistent with selection on variability preferentially picking jets pointed closest to the line of sight, where the projected optical-radio position offsets are minimized and jet emission is maximally boosted in the observed frame. While only ~9% of ICRF objects exhibit such large photometric variability, these results suggest that taking source variability into account may provide a means of optimally weighting the optical-radio celestial reference frame link.

Keywords: Radio cores, Jets, Radio jets, Quasars, Blazars, Very long baseline interferometry, Active galaxies, Radio astrometry, Light curves, Active galactic nuclei, Space astrometry, Gaia
The Luminosity Function of Tidal Disruption Flares for the ZTF-I Survey. The high-cadence survey of the Zwicky Transient Facility (ZTF) has completely dominated the discovery of tidal disruption events (TDEs) in the past few years and resulted in the largest sample of TDEs with optical/UV light curves well sampled around their peaks, providing us an excellent opportunity to construct a peak luminosity function (LF) of tidal disruption flares (TDFs). The new construction is necessary particularly considering that the most updated LF reported in literature has been inferred from only 13 sources from five different surveys. Here we present the optical and blackbody LFs calculated by 33 TDFs discovered in the ZTF-I survey. The optical LF can be described by both a power-law profile ${dN}/{{dL}}_{g}\propto {L}_{g}^{-2.3\pm 0.2}$ , and a Schechter-like function. The blackbody LF can be described by a power-law profile ${dN}/{{dL}}_{\mathrm{bb}}\propto {L}_{\mathrm{bb}}^{-2.2\pm 0.2}$ , shallower than the LF made of the previous van Velzen (2018) sample. A possible low-luminosity turnover in the optical LF supports an Eddington-limited emission scenario. The drop of the volumetric rate at high luminosity suggests a rate suppression due to direct captures of the black hole. The total volumetric rate is 1 order of magnitude lower than the previous estimation, which is probably not simply caused by the high fraction postpeak sources (7/13) in the previous sample. Instead, the normalization step during the previous LF construction to reconcile various surveys might adversely amplify the influence of serendipitous discoveries. Therefore, TDFs selected from ongoing and upcoming uniform surveys like ZTF, Vera Rubin Observatory, and the Wide-Field Survey Telescope should yield more accurate LFs.

Keywords: Luminosity function, Accretion, Wide-field telescopes, Tidal disruption, Transient sources, Time domain astronomy
On the Sound Speed in Neutron Stars. Determining the sound speed c  s  in compact stars is an important open question with numerous implications on the behavior of matter at large densities and hence on gravitational-wave emission from neutron stars. To this scope, we construct more than 107 equations of state (EOSs) with continuous sound speed and build more than 108 nonrotating stellar models consistent not only with nuclear theory and perturbative QCD, but also with astronomical observations. In this way, we find that EOSs with subconformal sound speeds, i.e., with ${c}_{s}^{2}\lt 1/3$ within the stars, are possible in principle but very unlikely in practice, being only 0.03% of our sample. Hence, it is natural to expect that ${c}_{s}^{2}\gt 1/3$ somewhere in the stellar interior. Using our large sample, we obtain estimates at 95% credibility of neutron-star radii for representative stars with 1.4 and 2.0 solar masses, ${R}_{1.4}={12.42}_{-0.99}^{+0.52}\,\mathrm{km}$ , ${R}_{2.0}={12.12}_{-1.23}^{+1.11}\,\mathrm{km}$ , and for the binary tidal deformability of the GW170817 event, ${\tilde{{\rm{\Lambda }}}}_{1.186}={485}_{-211}^{+225}$ . Interestingly, our lower bounds on the radii are in very good agreement with the prediction derived from very different arguments, namely, the threshold mass. Finally, we provide simple analytic expressions to determine the minimum and maximum values of $\tilde{{\rm{\Lambda }}}$ as a function of the chirp mass.

Keywords: Neutron stars, Stellar interiors, Neutron star cores, Gravitation, Fundamental parameters of stars, Nuclear astrophysics, Nuclear physics
A General, Scale-independent Description of the Sound Speed in Neutron Stars. Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints, we construct a novel, scale-independent description of the sound speed in neutron stars, where the latter is expressed in a unit cube spanning the normalized radius, r/R, and the mass normalized to the maximum one, M/M TOV. From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with M/M TOV ≳ 0.7, reaching a constant value of ${c}_{s}^{2}\,=\,1/2$ as M → M TOV. We also show that the sound speed decreases below the conformal limit ${c}_{s}^{2}\,=\,1/3$ at the center of stars with M = M TOV. Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.

Keywords: Neutron stars, Gravitation, Fundamental parameters of stars, Nuclear astrophysics, Nuclear physics
Morphology Driven Evolution of Barred Galaxies in OMEGAWINGS Clusters. We present a study of barred galaxies in the cluster environment, exploiting a sample of galaxies drawn from the extended WIde-field Nearby Galaxy-cluster Survey (OmegaWINGS) that covers up to the outer regions of 32 local X-ray selected clusters. Barred galaxies are identified through a semiautomatic analysis of ellipticity and position angle profiles. We find, in agreement with previous studies, a strong codependence of the bar fraction with the galaxy stellar mass and morphological type, being maximum for massive late-type galaxies. The fraction of barred galaxies decreases with increasing cluster mass and with decreasing clustercentric distance, a dependence that vanishes once we control for morphological type, which indicates that the likelihood of a galaxy hosting a bar in the cluster environment is determined by its morphological transformation. At large clustercentric distances, we detect a dependence on the distance to the nearest neighbor galaxy, suggesting that tidal forces with close companions are able to suppress the formation of bars or even destroy them. Barred galaxies in our sample are either early-type, star-forming galaxies located within the virial radii of the clusters or late-type quenched galaxies found beyond the virial radii of the clusters. We propose a scenario in which already quenched barred galaxies that fall into the clusters are centrally rejuvenated by the interplay of the perturbed gas by ram pressure and the bar, in galaxies that are undergoing a morphological transformation.

Keywords: Galaxy clusters, Galaxy evolution
Tracking Halo Orbits and Their Mass Evolution around Large-scale Filaments. We have explored the dynamical and mass evolution of halos driven by large-scale filaments using a dark-matter-only cosmological simulation with the help of a phase-space analysis. Since a nonnegligible number of galaxies are expected to fall into the cluster environment through large-scale filaments, tracking how halos move around large-scale filaments can provide a more comprehensive view on the evolution of cluster galaxies. Halos exhibit orbital motions around filaments, which emerge as specific trajectories in a phase space composed of halos' perpendicular distance and velocity component with respect to filaments. These phase-space trajectories can be represented by three cases according to their current states. We parameterize the trajectories with halos' initial position and velocity, maximum velocity, formation time, and time since first crossing, which are found to be correlated with each other. These correlations are explained well in the context of the large-scale structure formation. The mass evolution and dynamical properties of halos seem to be affected by the density of filaments, which can be shown from the fact that halos around denser filaments are more likely to lose their mass and be bound within large-scale filaments. Finally, we reproduce the mass segregation trend around filaments found in observations. The mass segregation has been developed because halos that formed earlier approached filaments earlier, grew efficiently, and ended up being more massive. We also found that dynamical friction helps to retain this segregation trend.

Keywords: Galaxy dark matter halos, Cosmic web, Large-scale structure of the universe
Constraining the Position of the Knee in the Galactic Cosmic-Ray Spectrum with Ultra-high-energy Diffuse γ-Rays. The diffuse γ-ray emission was measured up to 957 TeV by the Tibet-ASγ experiment recently. Assuming that it is produced by the hadronic interaction between cosmic-ray nuclei and the interstellar medium, it requires that the cosmic-ray nuclei should be accelerated well beyond PeV energies. Measurements of the cosmic-ray spectra for different species show diverse results at present. The Tibet experiments showed that the spectrum of proton plus helium has an early knee below PeV. If this is correct, the diffuse γ-ray emission would suggest an additional component of Galactic cosmic rays above PeV energies. This second component may originate from a source population of so-called PeVatrons revealed by recent ultra-high-energy γ-ray observations and could contribute to the cosmic-ray fluxes up to the energy of the second knee. On the other hand, the KASCADE measurement showed that the knee of protons is higher than PeV. In this case, the diffuse γ-rays observed by Tibet-ASγ can be well accounted for by only one cosmic-ray component. These two scenarios (i.e., the Tibet and KASCADE knees) could be distinguished by the spectral structures of diffuse γ-rays and cosmic-ray nuclei. Future measurements of spectra of individual nuclei by HERD and LHAASO experiments and diffuse γ-rays by LHAASO can jointly constrain these two scenarios.

Keywords: Cosmic rays
Investigating the Effect of Galaxy Interactions on Star Formation at 0.5 &lt; z &lt; 3.0. Observations and simulations of interacting galaxies and mergers in the local universe have shown that interactions can significantly enhance the star formation rates (SFRs) and fueling of active galactic nuclei (AGN). However, at higher redshift, some simulations suggest that the level of star formation enhancement induced by interactions is lower due to the higher gas fractions and already increased SFRs in these galaxies. To test this, we measure the SFR enhancement in a total of 2351 (1327) massive (M * &gt; 1010 M ☉) major (1 &lt; M 1/M 2 &lt; 4) spectroscopic galaxy pairs at 0.5 &lt; z &lt; 3.0 with ∆V &lt; 5000 km s-1 (1000 km s-1) and projected separation &lt;150 kpc selected from the extensive spectroscopic coverage in the COSMOS and CANDELS fields. We find that the highest level of SFR enhancement is a factor of ${1.23}_{-0.09}^{+0.08}$ in the closest projected separation bin (&lt;25 kpc) relative to a stellar mass-, redshift-, and environment-matched control sample of isolated galaxies. We find that the level of SFR enhancement is a factor of ~1.5 higher at 0.5 &lt; z &lt; 1 than at 1 &lt; z &lt; 3 in the closest projected separation bin. Among a sample of visually identified mergers, we find an enhancement of a factor of ${1.86}_{-0.18}^{+0.29}$ (~3σ) for coalesced systems. For this visually identified sample, we see a clear trend of increased SFR enhancement with decreasing projected separation (2.40 ${}_{-0.37}^{+0.62}$ versus ${1.58}_{-0.20}^{+0.29}$ for 0.5 &lt; z &lt; 1.6 and 1.6 &lt; z &lt; 3.0, respectively). The SFR enhancements seen in our interactions and mergers are all lower than the level seen in local samples at the same separation, suggesting that the level of interaction-induced star formation evolves significantly over this time period.

Keywords: Galaxy evolution, Galaxy interactions, Galaxy mergers, Galaxies
Reclassifying Swift Gamma-Ray Bursts with Diverse Duration Distributions. We select the largest sample of Swift gamma-ray bursts (GRBs) so far to reexamine the classification in terms of time duration, hardness ratio, and physical collapse model. To analyze the sample selection effect, we divide the observed Swift GRB sample into four subsamples according to signal-to-noise level, spectral quality, and extended emission. First, we find that only the sample of Swift GRBs with well-measured peak energy can be evidently divided into two types at a boundary of ~1 s, and other data sets are well described by three Gaussian functions. Using Swift GRBs with known redshift, a Kolmogorov-Smirnov test shows the intrinsic duration distributions of five data sets are equally distributed. Second, we ascertain in the plane of hardness ratio versus duration that the hardness ratio of short GRBs is significantly higher than those of middle classes and long GRBs, while the latter two components are the same in statistics, implying the so-called middle class to be artificial. Third, we apply a collapse model to discriminate the boundaries between collapse and noncollapse Swift bursts. It is interesting to find that a significant fraction, ≥30%, of Swift short GRBs could have originated from the collapsing progenitors, while all long GRBs are produced from the collapsars only. Finally, we point out that short GRBs with extended emission are the main contributors to the noncollapsar population with longer duration.

Keywords: Gamma-ray bursts
Tell-tale Spectral Signatures of MHD-driven Ultrafast Outflows in AGNs. We aim to explore spectral signatures of the predicted multi-ion ultrafast outflows (UFOs) in the broadband X-ray spectra of active galactic nuclei by exploiting an accretion disk-wind model in the context of a simple magnetohydrodynamic (MHD) framework. We are focused primarily on examining the spectral dependences on a number of key properties: (1) ionizing luminosity ratio λ ion, (2) line-of-sight wind density slope p, (3) optical/UV-to-X-ray strength α OX, (4) inclination θ, (5) X-ray photon index Γ, and (6) wind density factor f  D . With an emphasis on radio-quiet Seyferts in the sub-Eddington regime, multi-ion UFO spectra are systematically calculated as a function of these parameters to show that MHD-driven UFOs imprint a unique asymmetric absorption line profile with a pronounced blue tail structure on average. Such a characteristic line signature is generic to the simplified MHD disk-wind models presented in this work due to their specific kinematics and density structure. The properties of these absorption line profiles could be utilized as a diagnostics to distinguish between different wind-driving mechanisms or even the specific values of given MHD wind parameters. We also present high-fidelity microcalorimeter simulations in anticipation of the upcoming XRISM/Resolve and Athena/X-IFU instruments to demonstrate that such a "tell-tale" sign may be immune to a spectral contamination by the presence of additional warm absorbers and partially covering gas.

Keywords: Black hole physics, Radiative magnetohydrodynamics, Quasar absorption line spectroscopy, Galaxy accretion disks, Plasma astrophysics, X-ray active galactic nuclei, Spectroscopy