Sazuna/UAT_keywords huggingface dataset:
Modeling the Mass Distribution and Gravitational Potential of Nearby Disk Galaxies: Implications for the Interstellar Medium Dynamical Equilibrium. We characterize stellar, gas, and dark matter mass distributions for 17 nearby massive disk galaxies from the PHANGS sample. This allows us to compute the gravitational potential that vertically confines the interstellar gas and determines its equilibrium scale height and weight. We first combine dynamical mass constraints from existing CO and H I rotation curves, together with stellar and gas mass estimates from near-infrared, CO, and H I data. These estimates incorporate current best practices in modeling stellar mass-to-light ratios and CO-to-H2 conversion factor variations. Then, we fit joint stellar─gas─dark matter mass models to the rotation curves, adopting the classic maximal disk assumption to account for remaining zero-point uncertainties on the stellar mass-to-light ratio. After obtaining three-component radial mass profiles, we calculate the vertical equilibrium gas scale height and interstellar medium (ISM) weight in the combined gravitational potential. We find the gas scale height Hgas increases from ≲100 pc in the inner disks to &gt;500 pc at large radii, consistent with observations of our Galaxy and other edge-on galaxies. The gas weight is dominated by stellar gravity at small radii, but the gas and dark matter gravity often become important beyond 3─6 times the stellar disk radial scale length. Both our gas scale height and weight estimates are dependent on the treatment of stellar disk scale height H⋆, with Hgas varying by 30%─40% when H⋆ varies by a factor of 3. The relationship between our refined ISM weight estimates and local star formation surface density generally agrees with previous observations and predictions from theory and simulations.

Keywords: Galaxy disks, Star formation, Galaxy kinematics, Interstellar medium, Galaxy rotation curves
McFACTS III: Compact Binary Mergers from Active Galactic Nucleus Disks over an Entire Synthetic Universe. The active galactic nucleus (AGN) channel for the formation of binary black hole (BBH) mergers has been previously studied as a potential formation channel for the merging compact binaries observed by the LIGO─Virgo─KAGRA (LVK) scientific collaboration. The first two papers in this series explored the McFACTS code for the evolution of black hole orbits in AGN accretion disks for individual galaxy models and described the characteristics of predicted BBH populations in realizations of those models (such as the correlation between mass ratio and aligned spin). In this work, we explore the impact of the properties of AGN host galaxies and assume an AGN lifetime and cosmological model for the density of AGN in a universe like our own. By sampling from an inferred population of AGN, we marginalize over galaxy mass to predict a population of BBH mergers observable by modern ground-based gravitational-wave observatories. We find that for reasonable assumptions, AGN disk environments may account for massive BBH mergers such as GW190521 and GW190929_012149. We find that the majority of observable BBH mergers from our simulation are expected to originate in galaxies with a supermassive black hole between 107 M⊙ and 109.4 M⊙. We also find that if hierarchical mergers from AGN disks account for a substantial part of the LVK population, our current models require an AGN lifetime of 0.5─2.5 Myr.

Keywords: Active galactic nuclei, Compact binary stars, Gravitational wave sources
A Multispecies Atmospheric Escape Model with Excited Hydrogen and Helium: Application to HD209458b. Atmospheric escape shapes exoplanet evolution and star–planet interactions, with He I 10830 Å absorption serving as a key tracer of mass loss in hot gas giants. However, transit depths vary significantly across observed systems for reasons that remain poorly understood. HD209458b, the archetypal hot-Jupiter, exhibits relatively weak He I 10830 Å and Hα absorption, which has been interpreted as evidence for a high H/He ratio (98/2), possibly due to diffusive separation. To investigate this possibility and other processes that control these transit depths, we reassess excitation and de-excitation rates for metastable helium and explore the impact of diffusion processes, stellar activity, and tidal forces on the upper atmosphere and transit depths using a model framework spanning the whole atmosphere. Our model reproduces the observed He I transit depth and Hα upper limit, showing strong diffusive separation. We match the observations assuming a photoelectron efficiency of 20%–40%, depending on the composition of the atmosphere, corresponding to mass-loss rates of 1.9–3 × 1010 g s‑1. We find that the He I 10830 Å transit depth is sensitive to both stellar activity and diffusion processes, while Hα is largely unaffected due to its strong dependence on Lyα excitation. These differences may help explain the system-to-system scatter seen in population-level studies of the He I line. While He I data alone may not tightly constrain mass-loss rates or temperatures, they do confirm atmospheric escape and help narrow the viable parameter space when interpreted with physically motivated models. Simultaneous observations of He I, Hα, and stellar activity indicators provide powerful constraints on upper atmosphere dynamics and composition, even in the absence of full transmission spectra.

Keywords: Exoplanet atmospheric structure, Upper atmosphere, Exoplanet atmospheric evolution
SMA and NOEMA Reveal Asymmetric Substructure in the Protoplanetary Disk of IRAS 23077+6707. We present high-resolution data of IRAS 23077+6707 ("Dracula's Chivito") with the Submillimeter Array (SMA at 1.33 mm/225.5 GHz) and the Northern Extended Millimeter Array (NOEMA at 2.7 mm/111.7 GHz and 3.1 mm/96.2 GHz). IRAS 23077+6707 is a highly inclined and newly discovered protoplanetary disk, first reported in 2024. We combine SMA baselines from the compact, extended, and very extended arrays, and NOEMA baselines from its A and C configurations, and present continuum images with resolution ≲0 .″ 8, which constitute the first subarcsecond resolution maps of IRAS 23077+6707. The images show extended linear emission that spans 5 .″ 6–6 .″ 1 as expected for a radially extended, highly inclined protoplanetary disk. Accompanied with lower-resolution data, we show that the disk has a steep spectral index, ranging from α = 3.2–3.9. We present evidence of multiple radial emission peaks and troughs in emission, which may originate in disk rings and a central cavity. We further present evidence that these radial structures are asymmetric; hosting a significant brightness asymmetry, with emission enhanced by up to 50% in the north versus the south. We discuss hypotheses about the potential origins of these features, including the possibility that IRAS 23077+6707 hosts a rare example of an eccentric protoplanetary disk, which can induce these radially asymmetric structures. We present a simple eccentric continuum model of IRAS 23077+6707, and show, for an eccentricity of e ≈ 0.26, that this can reproduce the bulk morphology of the emission.

Keywords: Herbig Ae/Be stars, Young stellar objects, Protoplanetary disks
Counterculture Stars: Slow and Retrograde Stars with Low-alpha Disk Abundances. The Milky Way is home to a thin disk that can be defined via kinematics and/or elemental abundances. The elemental abundance-defined thin disk, also called the low-alpha disk, is generally thought to comprise stars on planar, circular orbits that approximate the circular velocity curve. While this is an apt description for the majority of stars with thin-disk-like abundances, there are a number of interesting exceptions. In this analysis, we identify and investigate ∼70 stars with thin-disk-like abundances and very slow or retrograde Galactocentric azimuthal velocities. These stars could be kinematical outliers of the thin disk or elemental abundance outliers of the halo. Focusing first on the former, we introduce a number of mechanisms that could alter a thin disk orbit and cause the azimuthal velocity to become slow or retrograde. We then determine signatures for each mechanism and assess whether that mechanism is unlikely, plausible, or consistent given each star's reported properties. We find that at least one mechanism is plausible for each star, and the mechanism with the highest number of consistent candidate stars is dynamical ejection from stellar clusters. We next discuss scenarios that could produce halo stars with thin-disk abundances, and again identify stars that could be connected to these mechanisms. With this sample, we investigate rare processes, such as binary disruption by the central supermassive black hole, while also providing a unique perspective into the chemo-dynamics and structural components of the Milky Way.

Keywords: Milky Way disk, Hypervelocity stars, Runaway stars
Nature of High Equivalent Width Emitters in the Epoch of Reionization Revealed by JWST Medium-band Imaging. Extreme emission line galaxies (EELGs) at high redshifts are considered key contributors to cosmic reionization at z &gt; 6 due to their higher ionization efficiencies. We have identified 119 Hβ + [O III] emitters at z ∼ 7 selected by a flux excess in the medium-band filter F410M in the public James Webb Space Telescope Cycle-1 fields. Our emitters exhibit a wide range in rest-frame Hβ + [O III] equivalent width (EWs), 420 &lt; EW0 / Å &lt; 6850 (with the median value of ∼1700 Å). Among them, 19 are EW0 &gt; 3000 / Å, which represent extreme populations even in the context of recent findings with JWST. They are characterized by (i) low stellar mass (∼3 × 107 M⊙), (ii) blue colors (βUV ∼ ‑2.2), and (iii) low dust attenuation (AV ∼ 0.1 mag). We discuss the physical mechanisms responsible for the observed high rest-frame Hβ + [O III] EWs, including (1) photoionization by active galactic nucleus (AGN), (2) stellar photoionization in the vicinity of H II regions, and (3) radiative shocks powered by outflows either from AGN or massive stars. Notably, we find 13 emitters with spatially offset Hβ + [O III] emission compared to the UV and stellar components. Given the absence of obvious signatures of actively accreting black holes, these emitters are likely under strong feedback-driven winds from massive stars. Lastly, we report a unique overdensity of EELGs in one of the observed fields. The discovery of such a "star-bursting" overdensity supports the idea that large ionizing bubbles formed around some EEGLs in the early Universe.

Keywords: Starburst galaxies, Galaxy formation, High-redshift galaxy clusters, Emission line galaxies, James Webb Space Telescope, Galaxy evolution, High-redshift galaxies
Type Ia Supernova Progenitors and Surviving Companions within the Symbiotic Channel. The symbiotic channel of Type Ia supernovae progenitors is crucial for explaining the observed circumstellar material in some Type Ia supernovae. While extensive numerical and observational efforts have been dedicated to exploring their progenitor systems, limited emphasis has been placed on studying the surviving companions arising from the symbiotic channel. In this paper, we present a numerical study of symbiotic systems using MESA simulated stars as potential Type Ia supernova progenitors. We conduct 1260 binary stellar evolution simulations, over a wide range of parameters, incorporating the optically thick wind model developed by I. Hachisu et al., and predict the postimpact evolution of these surviving companions. We classify four types of progenitor systems based on the evolutionary stage of the companion at the onset of the explosion: red giant companions, with or without a prior helium flash event, and asymptotic giant branch companions, with or without the thermal pulsing phase. After the supernova impact, a blue dwarf star with either a helium or carbon–oxygen core is left behind. However, if a small portion of the envelope (≳0.3%) remains on the core of the surviving companion, the overall postsupernova evolution may remain similar to its preexplosion state, albeit slightly fainter, making observation a challenging endeavor.

Keywords: Hydrodynamical simulations, White dwarf stars, Asymptotic giant branch stars, Type Ia supernovae, Companion stars, Symbiotic binary stars
The Connection between Galaxy Mergers, Star Formation, and Active Galactic Nuclei Activity in the HSC-SSP. Internal gas inflows driven by galaxy mergers are considered to enhance star formation rates (SFRs), fuel supermassive black hole growth, and stimulate active galactic nuclei (AGNs). However, quantifying these phenomena remains a challenge, due to difficulties both in classifying mergers and in quantifying galaxy and AGN properties. We quantitatively examine the merger–SFR–AGN connection using Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) galaxies using novel methods for both galaxy classification and property measurements. Mergers in HSC-SSP observational images are identified through fine-tuning Zoobot, a pretrained deep representation learning model, using images and labels based on the Galaxy Cruise project. We use galaxy and AGN properties that were produced by fitting Galaxy and Mass Assembly spectra using the spectral energy distribution fitting code PROSPECT, which fits panchromatically across the far-ultraviolet through far-infrared wavelengths and obtains galaxy and AGN properties simultaneously. Small differences are seen in SFR and AGN activity between mergers and controls, with ΔSFR = ‑0.009 ± 0.003 dex, ΔfAGN = ‑0.010 ± 0.033 dex, and ΔLAGN = 0.002 ± 0.025 dex. After further visual purification of the merger sample, we find ΔSFR = ‑0.033 ± 0.014 dex, ΔfAGN = ‑0.024 ± 0.170 dex, and ΔLAGN = 0.019 ± 0.129 dex for pairs, and ΔSFR = ‑0.057 ± 0.024 dex, ΔfAGN = 0.286 ± 0.270 dex, and ΔLAGN = 0.329 ± 0.195 dex for postmergers. These numbers suggest secular processes being an important driver for star formation and AGN activity, and present a cautionary tale when using longer-timescale tracers.

Keywords: Active galaxies, Interacting galaxies
The TeV Spectral Bump of Cosmic-Ray Protons and Helium Nuclei: The Role of Nearby Supernova Remnants. The existence of nearby discrete cosmic-ray (CR) sources can lead to many interesting effects on the observed properties of CRs. Recent measurements of CRs with the CALET and the DAMPE experiments have revealed a bump-like new feature in the proton and helium spectra in the energy range ∼(1–100) TeV n‑1. The origin of the feature is not clearly understood. In this paper, considering an improved and more detailed analysis than previous works, and using updated age and distance estimates of nearby supernova remnants (SNRs) along with an energy-dependent escape process for CRs from the remnants, we show that the spectral bump can be explained by the contribution of CRs from the nearby SNRs, in particular the Vela remnant. We also show that the contribution from the nearby remnants agrees well with the observed spectra of the heavier CR elements from carbon to iron, as well as with the measured all-particle CR spectrum beyond the knee region when combined with a background flux of CRs originating from distant SNRs.

Keywords: Galactic cosmic rays, Shocks, Supernova remnants, Particle astrophysics
The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-Ray Source at z = 10.145. We present James Webb Space Telescope (JWST)/NIRSpec PRISM spectroscopic characterization of GHZ9 at z = 10.145 ± 0.010, currently the most distant source detected by the Chandra X-ray Observatory. The spectrum reveals several UV high-ionization lines, including C II, Si IV, N IV], C IV, He II, O III], N III], and C III]. The prominent rest-frame equivalent widths (EW(C IV) ≃ 65 Å, EW(O III]) ≃ 28 Å, and EW(C III]) ≃ 48 Å) show the presence of a hard active galactic nucleus (AGN) radiation field, while line ratio diagnostics are consistent with either AGN or star formation as the dominant ionizing source. GHZ9 is nitrogen-enriched (6─9.5 (N/O)⊙), carbon-poor (0.2─0.65 (C/O)⊙), metal-poor (Z = 0.01─0.1 Z⊙), and compact (&lt;106 pc), similarly to GN-z11, GHZ2, and recently discovered N-enhanced high redshift objects. We exploited the newly available JWST/NIRSpec and NIRCam data set to perform an independent analysis of the Chandra data confirming that GHZ9 is the most likely JWST source associated with X-ray emission at 0.5─7 keV. Assuming a spectral index Γ = 2.3 (1.8), we estimate a black hole (BH) mass of 1.60 ± 0.31 (0.48 ± 0.09) × 108M⊙, which is consistent either with Eddington-accretion onto heavy (≥106M⊙) BH seeds formed at z = 18 or super-Eddington accretion onto a light seed of ∼102─104M⊙at z = 25. The corresponding BH-to-stellar mass ratio MBH/Mstar = 0.33 ± 0.22 (0.10 ± 0.07), with a stringent limit &gt;0.02, implies an accelerated growth of the BH mass with respect to the stellar mass. GHZ9 is the ideal target to constrain the early phases of AGN─galaxy coevolution with future multifrequency observations.

Keywords: Primordial galaxies, Active galactic nuclei, X-ray active galactic nuclei, High-redshift galaxies
The Effect of Weak Cosmic-ray Heating Events on the Desorption of H<SUB>2</SUB>. The typical amount of molecular hydrogen (H2) in interstellar ices is not known, but significant freeze-out of H2 on dust grains is not expected. However, chemical models ubiquitously predict large amounts of H2 freeze-out in dense cloud conditions, and specialized treatments are needed to control the H2 population on grains. Here we present a numerical desorption model where the effect of weak heating events induced by cosmic rays (CRs) that heat grains to temperatures of a few tens of kelvin at high frequencies is included, improving upon earlier desorption models that only consider strong heating events (maximum grain temperature close to 100 K) that occur at a low frequency. A temperature of a few tens of kelvin is high enough to induce efficient desorption of H2, but we find that even the weak heating events do not occur often enough to lead to significant H2 desorption. Taking the weak heating events into account does affect the predicted abundances of other lightly bound species, but the effect is restricted to low column densities. We make here the canonical assumption that the grains are spherical with a radius of 0.1 μm. It is conceivable that in the case of a grain size distribution, weak heating events could provide a boost to H2 desorption coming off small grains, which are the most numerous. Further studies are still required to better quantify the role of CRs in the desorption of H2 and other weakly bound species.

Keywords: Interstellar dust, Ice formation, Astrochemistry, Star formation, Interstellar medium, Cosmic rays
Calibrating the DM<SUB>IGM</SUB>–z Relation Using Host Galaxy Properties of Fast Radio Bursts. Fast radio bursts (FRBs) are extragalactic radio transients that offer valuable insight into the intergalactic medium (IGM). However, the dispersion measure (DM) contributed by the IGM (DMIGM) is degenerate with that from the host galaxy (DMhost), necessitating calibration of the DMIGM‑z relation for cosmological applications. As DMhost is expected to correlate with host galaxy properties, it is feasible to estimate DMhost from observable host characteristics. In this study, we conduct spectral energy distribution and Sérsic model fittings to derive the parameters of FRB host galaxies. Then, we examine the correlations between the excess dispersion measure (DMexc) and host galaxy parameters, including star formation rate, stellar mass, specific star formation rate (sSFR), inclination angle, and projected area. A tight correlation between DMexc and sSFR is found. This correlation is utilized to estimate DMhost of FRBs, providing a method to calibrate the DMIGM–z relation. This approach leads to a notable improvement in calibration performance.

Keywords: Radio bursts, Star formation, Interstellar medium, Galaxies, Radio transient sources
Modeling the High-brightness State of the Recurrent Nova T CrB as an Enhanced Mass-transfer Event. T Coronae Borealis is the nearest symbiotic recurrent nova. Twice in the last two centuries, in 1866 and 1946, the accreted material ignited on the surface of the white dwarf via runaway thermonuclear fusion reactions and produced a nova eruption. Both eruptions occurred approximately midway through a transient state of high luminosity. A possible explanation of such a state is a dwarf-nova-like outburst, which may arise from a transient increase in the mass-transfer rate of the donor star. We simulate the response of an accretion disk to an event of enhanced mass-transfer that is "interrupted" by a pre-eruption dip associated with the convective phase leading to the thermonuclear runaway. We model the resulting optical light curve using the parameters of the T CrB binary. Our model represents the first attempt to reproduce the transient high-accretion state. The observed brightening can be satisfactorily reproduced by models of an accretion disk with a viscosity parameter α = 3, an event of enhanced mass-transfer with a duration of Δt = 15 yr, and quiescent and high-state mass-transfer rates of 2.0 × 10‑9 M⊙ yr‑1 and 1.9 × 10‑7 M⊙ yr‑1, respectively, while the pre-eruption dip can be reproduced by the small, accelerated expansion of the inner disk's radius, at an average velocity of 0.02 km s‑1. Our model is also capable of reproducing the observed changes in color of T CrB throughout the transient event.

Keywords: Interacting binary stars, Recurrent novae, Stellar accretion disks, Symbiotic binary stars, Astronomical simulations
The HST–Gaia Near-infrared Astrometric Reference Frame Near the Milky Way Galactic Center. We present the first high-precision proper-motion catalog, tied to the International Celestial Reference System (ICRS), of infrared astrometric reference stars within R ≤ 25″ (1 pc) of the central supermassive black hole at the Galactic center (GC). This catalog contains ∼2900 sources in a highly extinguished region that is inaccessible via Gaia. New astrometric measurements are extracted from Hubble Space Telescope (HST) observations (14 epochs, 2010–2023) and transformed into the ICRS using 40 stars in common with Gaia-DR3. We implement a new method for modeling proper motions via Gaussian processes that accounts for systematic errors, greatly improving measurement accuracy. Proper-motion and position measurements reach precisions of ∼0.03 mas yr‑1 and ∼0.11 mas, respectively, representing a factor of ∼20 improvement over previous ICRS proper-motion catalogs in the region. These measurements define a novel HST–Gaia reference frame that is consistent with Gaia-CRF3 to within 0.025 mas yr‑1 in proper motion and 0.044 mas in position, making it the first ICRS-based reference frame precise enough to probe the distribution of extended mass within the orbits of stars near SgrA*. In addition, HST-Gaia provides an independent test of the radio measurements of stellar masers that form the basis of current GC reference frames. We find that the HST–Gaia and radio measurements are consistent to within 0.041 mas yr‑1 in proper motion and 0.54 mas in position at 99.7% confidence. Gaia-DR4 is expected to reduce the HST–Gaia reference-frame uncertainties by another factor of ∼2, further improving the reference frame for dynamical studies.

Keywords: Astronomical coordinate systems, Galactic center, Astrometry, Proper motions