Sazuna/UAT_keywords huggingface dataset:
Cover Your Basis: Comprehensive Data-driven Characterization of the Binary Black Hole Population. We introduce the first complete nonparametric model for the astrophysical distribution of the binary black hole (BBH) population. Constructed from basis splines, we use these models to conduct the most comprehensive data-driven investigation of the BBH population to date, simultaneously fitting nonparametric models for the BBH mass ratio, spin magnitude and misalignment, and redshift distributions. With GWTC-3, we report the same features previously recovered with similarly flexible models of the mass distribution, most notably the peaks in merger rates at primary masses of ~10M ⊙ and ~35M ⊙. Our model reports a suppressed merger rate at low primary masses and a mass-ratio distribution consistent with a power law. We infer a distribution for primary spin misalignments that peaks away from alignment, supporting conclusions of recent work. We find broad agreement with the previous inferences of the spin magnitude distribution: the majority of BBH spins are small (a &lt; 0.5), the distribution peaks at a ~ 0.2, and there is mild support for a nonspinning subpopulation, which may be resolved with larger catalogs. With a modulated power law describing the BBH merger rate's evolution in redshift, we see hints of the rate evolution either flattening or decreasing at z ~ 0.2-0.5, but the full distribution remains entirely consistent with a monotonically increasing power law. We conclude with a discussion of the astrophysical context of our new findings and how nonparametric methods in gravitational-wave population inference are uniquely poised to complement to the parametric approach as we enter the data-rich era of gravitational-wave astronomy.

Keywords: Black holes, High energy astrophysics, Gravitational wave astronomy, Gravitational waves, Compact objects
Energetics of Shock-triggered Supersubstorms (SML &lt; -2500 nT). The solar wind energy input and dissipation in the magnetospheric-ionospheric systems of 17 supersubstorms (SSSs: SML &lt; -2500 nT) triggered by interplanetary shocks during solar cycles 23 and 24 are studied in detail. The SSS events had durations ranging from ~42 minutes to ~6 hr, and SML intensities ranging from -2522 nT to -4143 nT. Shock compression greatly strengthens the upstream interplanetary magnetic field southward component (B s), and thus, through magnetic reconnection at the Earth's dayside magnetopause, greatly enhances the solar wind energy input into the magnetosphere and ionosphere during the SSS events studied. The additional solar wind magnetic reconnection energy input supplements the ~1.5 hr precursor (growth-phase) energy input and both supply the necessary energy for the high-intensity, long-duration SSS events. Some of the solar wind energy is immediately deposited in the magnetosphere/ionosphere system, and some is stored in the magnetosphere/magnetotail system. During the SSS events, the major part of the solar wind input energy is dissipated into Joule heating (~30%), with substantially less energy dissipation in auroral precipitation (~3%) and ring current energy (~2%). The remainder of the solar wind energy input is probably lost down the magnetotail. It is found that during the SSS events, the dayside Joule heating is comparable to that of the nightside Joule heating, giving a picture of the global energy dissipation in the magnetospheric/ionospheric system, not simply a nightside-sector substorm effect. Several cases are shown where an SSS is the only substorm that occurs during a magnetic storm, essentially equating the two phenomena for these cases.

Keywords: Space weather, Interplanetary shocks, Interplanetary magnetic fields
Nitrogen as a Tracer of Giant Planet Formation. I. A Universal Deep Adiabatic Profile and Semianalytical Predictions of Disequilibrium Ammonia Abundances in Warm Exoplanetary Atmospheres. A major motivation of spectroscopic observations of giant exoplanets is to unveil planet formation processes from atmospheric compositions. Several recent studies suggested that atmospheric nitrogen, like carbon and oxygen, can provide important constraints on planetary formation environments. Since nitrogen chemistry can be far from thermochemical equilibrium in warm atmospheres, we extensively investigate under what conditions, and with what assumptions, the observable NH3 abundances can diagnose an atmosphere's bulk nitrogen abundance. In the first paper of this series, we investigate atmospheric T-P profiles across equilibrium temperature, surface gravity, intrinsic temperature, atmospheric metallicity, and C/O ratio using a 1D radiative-convective equilibrium model. Models with the same intrinsic temperature and surface gravity coincide with a shared "universal" adiabat in the deep atmosphere, across a wide equilibrium temperature range (250-1200 K), which is not seen in hotter or cooler models. We explain this behavior in terms of the classic "radiative zero solution" and then establish a semianalytical T-P profile of the deep atmospheres of warm exoplanets. This profile is then used to predict vertically quenched NH3 abundances. At solar metallicity, our results show that the quenched NH3 abundance only coincides with the bulk nitrogen abundance (within 10%) at low intrinsic temperature, corresponding to a planet with a sub-Jupiter mass (≲1 M J) and old age (≳1 Gyr). If a planet has a high-metallicity (≳10× solar) atmosphere, the quenched NH3 abundance significantly underestimates the bulk nitrogen abundance at almost all planetary masses and ages. We suggest modeling and observational strategies to improve the assessment of bulk nitrogen from NH3.

Keywords: Exoplanet atmospheric composition , Chemical abundances, Exoplanet atmospheres, Exoplanet atmospheric structure
A Systematic View of Ten New Black Hole Spins. The launch of NuSTAR and the increasing number of binary black hole (BBH) mergers detected through gravitational wave observations have exponentially advanced our understanding of BHs. Despite the simplicity owed to being fully described by their mass and angular momentum, BHs have remained mysterious laboratories that probe the most extreme environments in the universe. While significant progress has been made in the recent decade, the distribution of spin in BHs has not yet been understood. In this work, we provide a systematic analysis of all known BHs in X-ray binary systems (XBs) that have previously been observed by NuSTAR, but have not yet had a spin measurement made using the "relativistic reflection" method obtained from those data. By looking at all the available archival NuSTAR data of these sources, we measure 10 new BH spins: IGR J17454-2919 - $a={0.97}_{-0.17}^{+0.03};$ GRS 1758-258 - $a={0.991}_{-0.019}^{+0.007};$ MAXI J1727-203 - $a={0.986}_{-0.159}^{+0.012};$ MAXI J0637-430 - a = 0.97 ± 0.02; Swift J1753.5-0127 - $a={0.997}_{-0.003}^{+0.001};$ V4641 Sgr - $a={0.86}_{-0.06}^{+0.04};$ 4U 1543-47 - $a={0.98}_{-0.02}^{+0.01};$ 4U 1957+11 - $a={0.95}_{-0.04}^{+0.02};$ H 1743-322 - $a={0.98}_{-0.02}^{+0.01};$ and MAXI J1820+070 - $a={0.988}_{-0.028}^{+0.006}$ (all uncertainties are at the 1σ confidence level). We discuss the implications of our measurements on the entire distribution of stellar-mass BH spins in XBs, and we compare them with the spin distribution in BBHs, finding that the two distributions are clearly in disagreement. Additionally, we discuss the implications of this work on our understanding of how the "relativistic reflection" spin measurement technique works, and discuss possible sources of systematic uncertainty that can bias our measurements.

Keywords: Accretion, X-ray binary stars, Black holes, Stellar mass black holes, Astrophysical black holes
Machine Learning Detects Multiplicity of the First Stars in Stellar Archaeology Data. In unveiling the nature of the first stars, the main astronomical clue is the elemental compositions of the second generation of stars, observed as extremely metal-poor (EMP) stars, in the Milky Way. However, no observational constraint was available on their multiplicity, which is crucial for understanding early phases of galaxy formation. We develop a new data-driven method to classify observed EMP stars into mono- or multi-enriched stars with support vector machines. We also use our own nucleosynthesis yields of core-collapse supernovae with mixing fallback that can explain many of the observed EMP stars. Our method predicts, for the first time, that 31.8% ± 2.3% of 462 analyzed EMP stars are classified as mono-enriched. This means that the majority of EMP stars are likely multi-enriched, suggesting that the first stars were born in small clusters. Lower-metallicity stars are more likely to be enriched by a single supernova, most of which have high carbon enhancement. We also find that Fe, Mg. Ca, and C are the most informative elements for this classification. In addition, oxygen is very informative despite its low observability. Our data-driven method sheds a new light on solving the mystery of the first stars from the complex data set of Galactic archeology surveys.

Keywords: Population II stars, Support vector machine, Population III stars, Milky Way formation
Solar Energetic Particle Events with Short and Long Onset Times. Gradual solar energetic particle (SEP) events, usually attributed to shock waves driven by coronal mass ejections (CMEs), show a wide variety of temporal behaviors. For example, TO, the &gt;10 MeV proton onset time with respect to the launch of the CME, has a distribution of at least an order of magnitude, even when the source region is not far from the so-called well-connected longitudes. It is important to understand what controls TO, especially in the context of space weather prediction. Here we study two SEP events from the western hemisphere that are different in TO on the basis of &gt;10 MeV proton data from the Geostationary Operations Environmental Satellite, despite being similar in the CME speed and longitude of the source regions. We try to find the reasons for different TO, or proton release times, in how the CME-driven shock develops and the Alfvén Mach number of the shock wave reaches some threshold by combining the CME height-time profiles with radio dynamic spectra. We also discuss how CME-CME interactions and active region properties may affect the proton release times.

Keywords: Solar energetic particles, Solar coronal mass ejection shocks, Space weather, Solar coronal mass ejections
IC 5146 Dark Streamer: The First Reliable Candidate of Edge Collapse, Hub-filament Systems, and Intertwined Sub-filaments. The paper presents an analysis of multiwavelength data of a nearby star-forming site, the IC 5146 dark streamer (d ~ 600 pc), which has been treated as a single and long filament, fl. Two hub-filament systems (HFSs) are known to exist toward the eastern and the western ends of fl. Earlier published results favor simultaneous evidence of HFSs and end-dominated collapse (EDC) in fl. A Herschel column density map (resolution ~13.″5) reveals two intertwined sub-filaments (i.e., fl-A and fl-B) toward fl, displaying a nearly double helix-like structure. This picture is also supported by the C18O(3-2) emission. The fray and fragment scenario may explain the origin of intertwined sub-filaments. In the direction of fl, two cloud components around 2 and 4 km s-1 are depicted using 13CO(1-0) and C18O(1-0) emission and are connected in velocity space. The HFSs are spatially found at the overlapping areas of these cloud components and can be explained by the cloud-cloud collision scenario. Nonthermal gas motion in fl with a larger Mach number is found. The magnetic field position angle measured from the filament's long axis shows a linear trend along the filament. This signature is confirmed in the other nearby EDC filaments, presenting a more quantitative confirmation of the EDC scenario. Based on our observational outcomes, we witness multiple processes operational in the IC 5146 streamer. Overall, the streamer can be recognized as the first reliable candidate for edge collapse, HFSs, and intertwined sub-filaments.

Keywords: Star forming regions, Molecular clouds, Young stellar objects, Interstellar emissions, H II regions
Emission Lines of Fe XIV, Fe XV, and Fe XVI in the Extreme Ultraviolet Region 40-100 Å. We report on emission spectra of iron in the extreme ultraviolet recorded at an electron density of ~1011 cm-3 on the Lawrence Livermore electron beam ion trap facility. We present a summary of the observed emission lines, including wavelengths and emission intensities, and present spectra of pure Fe XIV through Fe XVI emission derived from our measurements in the 40-100 Å wavelength range. We show that spectral models, especially the current version of CHIANTI v10.0, describe the M-shell emission from these three charge states of iron reasonably well, and we are able to verify several transitions in CHIANTI for the first time.

Keywords: Atomic spectroscopy, Stellar coronae, Laboratory astrophysics, Line positions
On the Spectral Evolution of Hot White Dwarf Stars. IV. The Diffusion and Mixing of Residual Hydrogen in Helium-rich White Dwarfs. In the framework of our extensive modeling study of the spectral evolution of white dwarfs, we present here a new set of detailed calculations of the transport of residual hydrogen in helium-rich white dwarfs. First, we investigate the so-called float-up process at high effective temperatures, whereby the upward diffusion of trace hydrogen leads to the formation of a hydrogen atmosphere. We examine the dependence of this phenomenon on the initial hydrogen abundance and on the strength of the radiative wind that opposes gravitational settling. Combined with our empirical knowledge of spectral evolution, our simulations provide new quantitative constraints on the hydrogen content of the hot helium-dominated white dwarf population. Then, we study the outcome of the so-called convective dilution process at low effective temperatures, whereby the superficial hydrogen layer is mixed within the underlying helium-rich envelope. In stark contrast with previous works on convective dilution, we demonstrate that, under reasonable assumptions, our models successfully reproduce the observed atmospheric composition of cool DBA stars, thereby solving one of the most important problems of the theory of spectral evolution. This major improvement is due to our self-consistent modeling of the earlier float-up process, which predicts the existence of a massive hydrogen reservoir underneath the thin superficial layer. We argue that the trace hydrogen detected at the surface of DBA white dwarfs is, in most cases, of primordial origin rather than the result of external accretion.

Keywords: DB stars, Stellar convection envelopes, White dwarf stars, DO stars, Stellar evolutionary models, Stellar diffusion, Stellar winds, DA stars, Atmospheric composition
The Mass Fallback Rate of the Debris in Relativistic Stellar Tidal Disruption Events. Highly energetic stellar tidal disruption events (TDEs) provide a way to study black hole characteristics and their environment. We simulate TDEs with the PHANTOM code in a general relativistic and Newtonian description of a supermassive black hole's gravity. Stars, which are placed in parabolic orbits with different β parameters, are constructed with the stellar evolution code MESA and therefore have realistic stellar density profiles. We study the mass fallback rate of the debris $\dot{M}$ and its dependence on β, stellar mass, and age as well as the supermassive black hole's spin and the choice of the gravity description. We calculate the peak value ${\dot{M}}_{\mathrm{peak}}$ , time to peak t peak, duration of the super-Eddington phase t Edd, time ${t}_{\gt 0.5{\dot{M}}_{\mathrm{peak}}}$ during which $\dot{M}\gt 0.5{\dot{M}}_{\mathrm{peak}}$ , early rise-time τ rise, and late-time slope n ∞. We recover the trends of ${\dot{M}}_{\mathrm{peak}}$ , t peak, τ rise, and n ∞ with β, stellar mass, and age which were obtained in previous studies. We find that t Edd, at a fixed β, scales primarily with the stellar mass, while ${t}_{\gt 0.5{\dot{M}}_{\mathrm{peak}}}$ scales with the compactness of stars. The effect of the SMBH's rotation depends on the orientation of its rotational axis relative to the direction of the stellar motion in the initial orbit. Encounters in prograde orbits result in narrower $\dot{M}$ curves with higher ${\dot{M}}_{\mathrm{peak}}$ , while the opposite occurs for retrograde orbits. We find that disruptions, at the same pericenter distance, are stronger in a relativistic tidal field than in a Newtonian one. Therefore, relativistic $\dot{M}$ curves have higher ${\dot{M}}_{\mathrm{peak}}$ , and shorter t peak and t Edd.

Keywords: Black hole physics, Tidal disruption, Relativistic fluid dynamics, Hydrodynamical simulations
Toward Horizon-scale Accretion onto Supermassive Black Holes in Elliptical Galaxies. We present high-resolution, three-dimensional hydrodynamic simulations of the fueling of supermassive black holes in elliptical galaxies from a turbulent medium on galactic scales, taking M87* as a typical case. The simulations use a new GPU-accelerated version of the Athena++ AMR code, and they span more than six orders of magnitude in radius, reaching scales similar to that of the black hole horizon. The key physical ingredients are radiative cooling and a phenomenological heating model. We find that the accretion flow takes the form of multiphase gas at radii less than about a kpc. The cold gas accretion includes two dynamically distinct stages: the typical disk stage in which the cold gas resides in a rotationally supported disk, and relatively rare chaotic stages (≲10% of the time) in which the cold gas inflows via chaotic streams. Though cold gas accretion dominates the time-averaged accretion rate at intermediate radii, accretion at the smallest radii is dominated by hot virialized gas at most times. The accretion rate scales with radius as $\dot{M}\propto {r}^{1/2}$ when hot gas dominates, and we obtain $\dot{M}\simeq {10}^{-4}\mbox{--}{10}^{-3}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ near the event horizon, similar to what is inferred from EHT observations. The orientation of the cold gas disk can differ significantly on different spatial scales. We propose a subgrid model for accretion in lower-resolution simulations in which the hot gas accretion rate is suppressed relative to the Bondi rate by $\sim {({r}_{{\rm{g}}}/{r}_{\mathrm{Bondi}})}^{1/2}$ . Our results can also provide more realistic initial conditions for simulations of black hole accretion at the event horizon scale.

Keywords: Accretion, Supermassive black holes, Active galactic nuclei, Elliptical galaxies
Host Dark Matter Halos of Wide-field Infrared Survey Explorer-selected Obscured and Unobscured Quasars: Evidence for Evolution. Obscuration in quasars may arise from steep viewing angles along the dusty torus, or instead may represent a distinct phase of supermassive black hole growth. We test these scenarios by probing the host dark matter halo environments of ~1.4 million Wide-field Infrared Survey Explorer-selected obscured and unobscured quasars at &lt;z&gt; = 1.4 using angular clustering measurements as well as cross-correlation measurements of quasar positions with the gravitational lensing of the cosmic microwave background. We interpret these signals within a halo occupation distribution framework to conclude that obscured systems reside in more massive effective halos (~1012.9 h -1  M ⊙) than their unobscured counterparts (~1012.6  h -1 M ⊙), though we do not detect a difference in the satellite fraction. We find excellent agreement between the clustering and lensing analyses and show that this implies the observed difference is robust to uncertainties in the obscured quasar redshift distribution, highlighting the power of combining angular clustering and weak lensing measurements. This finding appears in tension with models that ascribe obscuration exclusively to orientation of the dusty torus along the line of sight, and instead may be consistent with the notion that some obscured quasars are attenuated by galaxy-scale or circumnuclear material during an evolutionary phase.

Keywords: Weak gravitational lensing, Galaxy dark matter halos, Large-scale structure of the universe, Quasars, Active galactic nuclei, Clustering, Galaxy evolution
The Ages of Galactic Bulge Stars with Realistic Uncertainties. Using modern isochrones with customized physics and carefully considered statistical techniques, we recompute the age distribution for a sample of 91 microlensed dwarfs in the Galactic bulge presented by Bensby et al. and do not produce an age distribution consistent with their results. In particular, our analysis finds that only 15 of 91 stars have ages younger than 7 Gyr, compared to their finding of 42 young stars in the same sample. While we do not find a constituency of very young stars, our results do suggest the presence of an ~8 Gyr population at the highest metallicities, thus contributing to the long-standing debate about the age-metallicity distribution of the Galactic bulge. We supplement this with attempts at independent age determinations from two sources of photometry, BDBS and Gaia, but find that the imprecision of photometric measurements prevents reliable age and age uncertainty determinations. Lastly, we present age uncertainties derived using a first-order consideration of global modeling uncertainties in addition to standard observational uncertainties. The theoretical uncertainties are based on the known variance of free parameters in the 1D stellar evolution models used to generate isochrones, and when included, result in age uncertainties of 2-5 Gyr for this spectroscopically well-constrained sample. These error bars, which are roughly twice as large as typical literature values, constitute realistic lower limits on the true age uncertainties.

Keywords: Stellar ages, Stellar evolutionary models, Galactic bulge
The Effect of Metallicity on the Nonequilibrium Abundance of Hydrogen-dominated Exoplanet Atmospheres. The atmospheric metallicity greatly influences the composition of exoplanet atmospheres. The effect of metallicity on the thermochemical equilibrium is well studied, though its effect on the disequilibrium abundance is loosely constrained. In this study, we have used the quenching approximation to study the effect of metallicity on the quenched abundance for a range of parameters (temperature: 500-2500 K, pressure: 10-4-103 bar, metallicity: 0.1-1000× solar metallicity). We determine the chemical timescale by finding rate-limiting steps in a reduced chemical network with a network-analysis tool and the thermochemical equilibrium abundance. The equilibrium abundance results are similar to the literature. The CO, H2O, and CO2 abundances increase with metallicity in the parameter range considered. The CH4 abundance increases with metallicity for CO/CH4 &lt; 1 and is unaffected for CO/CH4 &gt; 1. The chemical timescale of CO shows minimal change with metallicity, while the CH4 chemical timescale is inversely proportional to atmospheric metallicity. The quench level of CO shifts into the high-pressure region, and the quench level of CH4 shows complex behavior with metallicity. We benchmarked the quenching approximation with a one-dimensional photochemistry-transport model for two test exoplanets (GJ 1214 b and HD 189733 b) and found it to be in good agreement. We also found that the quenching approximation is a powerful tool to constrain atmospheric parameters. We demonstrated this by constraining the metallicity and transport strength for the test exoplanets HR 8799 b, HD 189733 b, GJ 436 b, and WASP-39 b.

Keywords: Atmospheric composition, Metallicity, Exoplanet atmospheres