Sazuna/UAT_keywords huggingface dataset:
Signatures of Mass Ratio Reversal in Gravitational Waves from Merging Binary Black Holes. The spins of merging binary black holes offer insights into their formation history. Recently it has been argued that in the isolated binary evolution of two massive stars the firstborn black hole is slowly rotating, while the progenitor of the second-born black hole can be tidally spun up if the binary is tight enough. Naively, one might therefore expect that only the less massive black hole in merging binaries exhibits nonnegligible spin. However, if the mass ratio of the binary is "reversed" (typically during the first mass transfer episode), it is possible for the tidally spun up second-born to become the more massive black hole. We study the properties of such mass ratio reversed binary black hole mergers using a large set of 560 population synthesis models. We find that the more massive black hole is formed second in ≳70% of binary black holes observable by LIGO, Virgo, and KAGRA for most model variations we consider, with typical total masses ≳20 M ⊙ and mass ratios q = m 2/m 1 ~ 0.7 (where m 1 &gt; m 2). The formation history of these systems typically involves only stable mass transfer episodes. The second-born black hole has nonnegligible spin (χ &gt; 0.05) in up to 25% of binary black holes, with among those the more (less) massive black hole is spinning in 0%-80% (20%-100%) of the cases, varying greatly in our models. We discuss our models in the context of several observed gravitational-wave events and the observed mass ratio-effective spin correlation.

Keywords: Gravitational waves, Gravitational wave sources, Astrophysical black holes
Informing the Cataclysmic Variable Sequence from Gaia Data: The Orbital-period-Color-Absolute-magnitude Relationship. The orbital-period (P orb) gap in the population of cataclysmic variables (CVs) informs the theoretical narrative of CV evolution, yet a complete understanding of the driving angular momentum loss mechanisms above and below this gap remains elusive. Here we identify, for standard CVs, a new, apparently monotonic relationship between quiescent color (G BP-G RP), absolute magnitude (M  G ), and P orb (between 70 minutes and 8 hr) revealed in Gaia DR2 and EDR3. We show that P orb increases in the color-absolute-magnitude diagram roughly orthogonally to the white dwarf and main sequences. We find the orbital-period-color-absolute-magnitude relationship to be stable across different CV subtypes: dwarf novae, intermediate polars, polars, and novalike systems. We place our findings in context with the known semiempirical donor sequence for CVs and find a dependence between color and M  G  for a given P orb specifically for dwarf novae and intermediate polars above the period gap. These relations have the potential to inform a more complete picture of CV evolution.

Keywords: Surveys, Close binary stars, Variable stars, Hertzsprung Russell diagram, Cataclysmic variable stars
The Absolute Magnitudes of 1991T-like Supernovae. 1991T-like supernovae are the luminous, slow-declining extreme of the Branch shallow-silicon (SS) subclass of Type Ia supernovae. They are distinguished by extremely weak Ca II H &amp; K and Si II λ6355 and strong Fe III absorption features in their optical spectra at pre-maximum phases, and have long been suspected to be over-luminous compared to normal Type Ia supernovae. In this paper, the pseudo-equivalent width of the Si II λ6355 absorption obtained at light curve phases from ≤ +10 days is combined with the morphology of the i-band light curve to identify a sample of 1991T-like supernovae in the Carnegie Supernova Project II. Hubble diagram residuals show that, at optical as well as near-infrared wavelengths, these events are over-luminous by ~0.1-0.5 mag with respect to the less extreme Branch SS (1999aa-like) and Branch core-normal supernovae with similar B-band light-curve decline rates. * This paper includes data gathered with the 6.5 meter Magellan telescopes at Las Campanas Observatory, Chile.

Keywords: Observational cosmology, Type Ia supernovae, Supernovae
Key Parameters Controlling the Photodesorption Yield in Interstellar CO Ice Analogs: The Influence of Ice Deposition Temperature and Thickness. The overabundance of gas molecules in the coldest regions of space points to a nonthermal desorption process. Laboratory simulations show the efficient desorption of CO ice that is exposed to ultraviolet radiation, known as photodesorption, which decreases with increasing ice deposition temperature. However, our understanding of this abnormal phenomenon still remains elusive. In this work, we show that the same phenomenon-and, in particular, a dramatic drop in the photodesorption yield-is observed when the deposition temperature is 19 K and higher. Also, the minimum ice thickness that accounts for a constant photodesorption yield of CO ice is dependent on the deposition temperature, an observation that is reported here for the first time. We propose that the key parameters dominating the absorbed photon energy transfer in CO ice, and contributing to the measured photodesorption yields, are the energy transfer length, the desorption yield contributed by a single ice layer, and the relative effective surface area. These parameters should be incorporated into astrophysical models that simulate the photodesorption of the top CO-rich ice layer in icy dust populations, with a size distribution that is related to the ice thickness.

Keywords: Molecular spectroscopy, Laboratory astrophysics, Interstellar medium
The Directly Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator. 51 Eri is well known for hosting a directly imaged giant planet and for its membership to the β Pictoris moving group. Using 2 minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS), we detect multiperiodic variability in 51 Eri that is consistent with pulsations of Gamma Doradus (γ Dor) stars. We identify the most significant pulsation modes (with frequencies between ~0.5 and 3.9 cycles day-1 and amplitudes ranging between ~1 and 2 mmag) as dipole and quadrupole gravity modes, as well as Rossby modes, as previously observed in Kepler γ Dor stars. Our results demonstrate that previously reported variability attributed to stellar rotation is instead likely due to γ Dor pulsations. Using the mean frequency of the ℓ = 1 gravity modes, together with empirical trends of the Kepler γ Dor population, we estimate a plausible stellar core rotation period of ${0.9}_{-0.1}^{+0.3}$ days for 51 Eri. We find no significant evidence for transiting companions around 51 Eri in the residual light curve. The detection of γ Dor pulsations presented here, together with follow-up observations and modeling, may enable the determination of an asteroseismic age for this benchmark system. Future TESS observations would allow a constraint on the stellar core rotation rate, which in turn traces the surface rotation rate, and thus would help clarify whether or not the stellar equatorial plane and orbit of 51 Eri b are coplanar.

Keywords: Stellar pulsations, Exoplanet systems, Variable stars, Planet hosting stars, Trinary stars, Gamma Doradus variable stars
Kinematical Constraint on Eccentricity in the Protoplanetary Disk MWC 758 with ALMA. We analyzed the archival data of the 13CO and C18O J = 3 - 2 emission lines in the protoplanetary disk around MWC 758 obtained with the Atacama Large Millimeter/submillimeter Array to discuss possible planet-disk interaction and non-Keplerian motion in the disk. We performed fitting of a Keplerian disk model to the observational data and measured the velocity deviations from the Keplerian rotation. We found significant velocity deviations around the inner cavity in the MWC 758 disk. We examined several possibilities that may cause the velocity deviations, such as pressure gradient, height of the emitting layer, infall motion, inner warp, and eccentricity in the disk. We found that the combination of an eccentric orbital motion with eccentricity of 0.1 ± 0.04 at the radius of the inner cavity and an infalling flow best explains the observed velocity deviations. Our kinematically constrained eccentricity of the gas orbital motion close to the inner cavity is consistent with the eccentricity of the dust ring around the inner cavity measured in the submillimeter continuum emission. Our results hint at strong dust-gas coupling around the inner cavity and presence of a gas giant planet inside the inner cavity in the MWC 758 disk.

Keywords: Planet formation, Planetary-disk interactions, Protoplanetary disks, Eccentricity
Suzaku Observations of the Cluster Outskirts and Intercluster Filament in the Triple Merger Cluster A98. We present Suzaku observations of the Abell 98 (A98) triple galaxy cluster system and the purported intercluster filament. The three subclusters are expected to lie along a large-scale cosmic filament. With partial azimuthal coverage of the northernmost cluster, we find that the inferred entropy profile of this relatively low-mass cluster (kT ≍ 2.8 keV) adheres to expectations from models of self-similar pure gravitational collapse in the region of the virial radius. There is evidence of extended structure beyond r 200 to the north of the northernmost cluster, along the merger axis, with properties consistent that are expected for the warm-hot intergalactic medium ( ${kT}={0.11}_{-0.02}^{+0.01}$ keV and n  e  = 7.6 × 10-5 ± 3.6 × 10-5 cm-3). No such emission is detected at the same radius in regions away from the merger axis, consistent with the expectation that the merger axis of this triple system lies along a large-scale cosmic filament. In the bridge region between A98N and A98S, there is evidence of filamentary emission at the 2.2σ level, as well as a tentative detection of cool gas (kT ~ 1 keV). The entropy profile of this intercluster filament suggests that the A98 system is most likely aligned closer to the plane of the sky rather than along the line of sight. The structure to the north of the system, as well as in-between A98N and A98S, is indicative that the clusters are connected to a larger-scale structure spanning at least 4 Mpc.

Keywords: Galaxy clusters, High energy astrophysics, Large-scale structure of the universe, Abell clusters, Intracluster medium
Probe for Type Ia Supernova Progenitor in Decihertz Gravitational Wave Astronomy. It is generally believed that Type Ia supernovae are thermonuclear explosions of carbon-oxygen white dwarfs (WDs). However, there is currently no consensus regarding the events leading to the explosion. A binary WD (WD-WD) merger is a possible progenitor of Type Ia supernovae. Space-based gravitational wave (GW) detectors with considerable sensitivity in the decihertz range such as the DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) can observe WD-WD mergers directly. Therefore, access to the decihertz band of GWs would enable multi-messenger observations of Type Ia supernovae to determine their progenitors and explosion mechanism. In this paper, we consider the event rate of WD-WD mergers and the minimum detection range to observe one WD-WD merger per year, using a nearby galaxy catalog and the relation between Ia supernovae and their host galaxies. Furthermore, we calculate DECIGO's ability to localize WD-WD mergers and to determine the masses of binary mergers. We estimate that a decihertz GW observatory can detect GWs with amplitudes of h ~ 10-20 [Hz-1/2] at 0.01-0.1 Hz, which is 1000 times higher than the detection limit of DECIGO. Assuming the progenitors of Ia supernovae are merging WD-WD (1 M ⊙ and 0.8 M ⊙), DECIGO is expected to detect 6600 WD-WD mergers within z = 0.08, and identify the host galaxies of such WD-WD mergers within z ~ 0.065 using GW detections alone.

Keywords: Gravitational wave astronomy, Type Ia supernovae
Testing Relativistic Reflection Models with GRMHD Simulations of Accreting Black Holes. X-ray reflection spectroscopy is currently one of the leading techniques for studying the inner part of accretion disks around black holes, measuring black hole spins, and even testing fundamental physics in strong gravitational fields. However, the accuracy of these measurements depends on the reflection models employed for the spectral analysis, which are sometimes questioned. In this work, we use a general relativistic magnetohydrodynamic code to generate a thin accretion disk in Kerr spacetime and ray-tracing techniques to calculate its relativistically broadened reflection spectrum. We simulate NuSTAR observations and we test the capability of current reflection models to recover the correct input parameters. Our study shows that we can measure the correct input parameters in the case of high inclination angle sources, while we find some minor discrepancies when the inclination angle of the disk is low.

Keywords: Accretion, X-ray astronomy, Astrophysical black holes
Discovery of a Brown Dwarf with Quasi-spherical Mass Loss. We report the serendipitous discovery of an elliptical shell of CO associated with the faint stellar object SSTc2d J163134.1-240060 as part of the "Ophiuchus Disk Survey Employing ALMA" (ODISEA), a project aiming to study the entire population of protoplanetary disks in the Ophiuchus Molecular Cloud from 230 GHz continuum emission and 12CO (J = 2-1), 13CO (J = 2-1) and C18CO (J = 2-1) lines readable in Band 6. Remarkably, we detect a bright 12CO elliptical shape emission of ~3″ × 4″ toward SSTc2d J163134.1-240060 without a 230 GHz continuum detection. Based on the observed near-IR spectrum taken with the Very Large Telescope (KMOS), the brightness of the source, its three-dimensional motion, and Galactic dynamic arguments, we conclude that the source is not a giant star in the distant background (&gt;5-10 kpc) and is most likely to be a young brown dwarf in the Ophiuchus cloud, at a distance of just ~139 pc. This is the first report of quasi-spherical mass loss in a young brown dwarf. We suggest that the observed shell could be associated with a thermal pulse produced by the fusion of deuterium, which is not yet well understood, but for a substellar object is expected to occur during a short period of time at an age of a few Myr, in agreement with the ages of the objects in the region. Other more exotic scenarios, such as a merger with planetary companions, cannot be ruled out from the current observations.

Keywords: Stellar winds, Circumstellar clouds, Stellar wind bubbles
Protostellar and Protoplanetary Disk Masses in the Serpens Region. We present the results from an Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum and 12CO (J = 2 - 1) line survey spread over 10 deg2 in the Serpens star-forming region of 320 young stellar objects, 302 of which are likely members of Serpens (16 Class I, 35 flat-spectrum, 235 Class II, and 16 Class III). From the continuum data, we derive disk dust masses and show that they systematically decline from Class I to flat-spectrum to Class II sources. Grouped by stellar evolutionary state, the disk mass distributions are similar to other young (&lt;3 Myr) regions, indicating that the large-scale environment of a star-forming region does not strongly affect its overall disk dust mass properties. These comparisons between populations reinforce previous conclusions that disks in the Ophiuchus star-forming region have anomalously low masses at all evolutionary stages. Additionally, we find a single deeply embedded protostar that has not been documented elsewhere in the literature and, from the CO line data, 15 protostellar outflows, which we catalog here.

Keywords: Submillimeter astronomy, Pre-main sequence stars, Protoplanetary disks
A Comparative L-dwarf Sample Exploring the Interplay between Atmospheric Assumptions and Data Properties. Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of five L dwarfs of similar effective temperature (T eff) or spectral type to compare their pressure-temperature (P-T) profiles. Additionally, we explore the impact of an object's metallicity and the signal-to-noise ratio (S/N) of the observations on the parameters we can retrieve. We present the first atmospheric retrievals: 2MASS J15261405+2043414, 2MASS J05395200-0059019, 2MASS J15394189-0520428, and GD 165B increasing the small but growing number of L dwarfs retrieved. When compared to the atmospheric retrievals of SDSS J141624.08+134826.7, a low-metallicity d/sdL7 primary in a wide L+T binary, we find that similar T eff sources have similar P-T profiles with metallicity differences impacting the relative offset between their P-T profiles in the photosphere. We also find that for near-infrared spectra, when the S/N is ≳80 we are in a regime where model uncertainties dominate over data measurement uncertainties. As such, S/N does not play a role in the retrieval's ability to distinguish between a cloud-free and cloudless model, but may impact the confidence of the retrieved parameters. Lastly, we also discuss how to break cloud model degeneracies and the impact of extraneous gases in a retrieval model.

Keywords: Brown dwarfs, Exoplanets, Fundamental parameters of stars, L dwarfs, Atmospheric composition, Metallicity, Stellar atmospheres
SN 1961V: A Pulsational Pair-instability Supernova. We explore a variety of models in which SN 1961V, one of the most enigmatic supernovae (SNe) ever observed, was a pulsational pair-instability supernova (PPISN). Successful models reproduce the bolometric light curve of the principal outburst and, in some cases, the emission 1 yr before and several years afterward. All models have helium-rich ejecta, bulk hydrogenic velocities near 2000 km s-1, and total kinetic energies of (4-8) × 1050 erg. Each eventually leaves behind a black hole remnant. Three subclasses of PPISN models are explored, each with two different choices of carbon abundance following helium burning. Carbon is an important parameter because shell carbon burning can weaken the explosion. The three subclasses correspond to situations where SN 1961V and its immediate afterglow were (a) a single event, (b) the first of two or more pulsational events separated by decades or centuries, or (c) the latter stages of a complex explosion that had already been going on for a year or more. For the low-carbon case, the main-sequence mass for SN 1961V's progenitor would have been 100-115 M ⊙, its pre-SN helium core mass was 45-52 M ⊙, and the final black hole mass was 40-45 M ⊙. For the high-carbon case, these values are increased by roughly 20%-25%. In some PPISN models, a ~1040 erg s-1 star-like object could still be shining at the site of SN 1961V, but it has more likely been replaced by a massive accreting black hole.

Keywords: Core-collapse supernovae, Type II supernovae, Massive stars, Stellar mass black holes, Supernovae, Supernova dynamics
The Effect of Light Deflection by Solar System Objects on High-precision Square Kilometre Array Astrometry. We have computed the deflection angles caused by 195 objects in the solar system, including 177 satellites, and eight asteroids; 21 satellites and six asteroids can bend light from distant compact extragalactic sources by more than 0.1 μas, and 14 satellites, and the asteroid Ceres can deflect light by more than 1.0 μas. We calculated the zones and durations of perturbations posed by the gravitational fields of five planets (excluding Earth, Jupiter, and Saturn), Pluto, and Ceres, where the perturbations would affect astrometry measured with the Square Kilometre Array (SKA). Perturbed zones with deflection angles larger than 0.1 and 1.0 μas appear as ribbons. Their widths range from dozens of degrees for Uranus, Neptune, and Venus to several degrees or less for other objects at 0.1 μas, and from ~16° for Venus to several degrees or less for other objects at 1.0 μas. From the calculated perturbation durations, the influence of the gravitational fields of selected objects can be divided into four levels: (i) hardly affects SKA astrometry, (ii) may have little effect, (iii) may have a great effect on single-epoch astrometry, and (iv) may greatly affect both single- and multiepoch astrometry. The objects corresponding to these levels are (i) Ceres, (ii) Pluto, (iii) Mercury and Mars, and (iv) other objects.

Keywords: Compact galaxies, Gravitation, Gravitational deflection, Radio astrometry, General relativity, Radio interferometry
Particle Acceleration Controlled by Ambient Density in the Southwestern Rim of RCW 86. The physics of particle acceleration at supernova remnant (SNR) shocks is one of the most intriguing problems in astrophysics. SNR RCW 86 provides a suitable environment for understanding the physics of particle acceleration because one can extract the information on both accelerated particles and acceleration environment in the same regions through the bright X-ray emission. In this work, we study X-ray proper motions and spectral properties of the southwestern region of RCW 86. The proper motion velocities are found to be ~300-2000 km s-1 at a distance of 2.8 kpc. We find two inward-moving filaments, which are more likely reflected shocks rather than reverse shocks. Based on the X-ray spectroscopy, we evaluate thermal parameters such as the ambient density and temperature, and nonthermal parameters such as the power-law flux and index. From the decrease in flux over time of several nonthermal filaments, we estimate the magnetic field amplitudes to be ~30-100 μG. Gathering the physical parameters, we then investigate parameter correlations. We find that the synchrotron emission from thermal-dominated filaments is correlated with the ambient density n e as (power-law flux) $\propto {n}_{{\rm{e}}}^{1.0\pm 0.2}$ and (power-law index) $\propto {n}_{{\rm{e}}}^{0.38\pm 0.10}$ , and not or only weakly correlated with the shock velocity and shock obliquity. As an interpretation, we propose a shock-cloud interaction scenario, where locally enhanced magnetic turbulence levels have a great influence on local acceleration conditions.

Keywords: Supernova remnants, Shocks, Type Ia supernovae, Galactic cosmic rays
A Novel Inversion Method to Determine the Coronal Magnetic Field Including the Impact of Bound-Free Absorption. The magnetic field governs the corona; hence, it is a crucial parameter to measure. Unfortunately, existing techniques for estimating its strength are limited by strong assumptions and limitations. These techniques include photospheric or chromospheric field extrapolation using potential or nonlinear force-free methods, estimates based on coronal seismology, or direct observations via, e.g., the Cryo-NIRSP instrument on DKIST, which will measure the coronal magnetic field but only off the limb. Alternately, in this work, we investigate a recently developed approach based on the magnetic-field-induced transition (MIT) of Fe X 257.261Å In order to examine this approach, we have synthesized several Fe X lines from two 3D magnetohydrodynamic simulations, one modeling an emerging flux region and the second an established mature active region. In addition, we take bound-free absorption from neutral hydrogen and helium and singly ionized helium into account. The absorption from cool plasma that occurs at coronal heights has a significant impact on determining the magnetic field. We investigate in detail the challenges of using these Fe X lines to measure the field, considering their density and temperature dependence. We present a novel approach to deriving the magnetic field from the MIT using inversions of the differential emission measure as a function of the temperature, density, and magnetic field. This approach successfully estimates the magnetic field strength (up to 18% relative error) in regions that do not suffer from significant absorption and that have relatively strong coronal magnetic fields (&gt;250 G). This method allows regions where absorption is significant to be masked.

Keywords: Solar active region magnetic fields, Solar ultraviolet emission, Solar extreme ultraviolet emission, Solar coronal lines, Active solar corona