Sazuna/UAT_keywords huggingface dataset:
A Near-infrared Look at AGN Feedback in Bulgeless Galaxies. While it is generally believed that supermassive black holes (SMBHs) lie in most galaxies with bulges, few SMBHs have been confirmed in bulgeless galaxies. Identifying such a population could provide important insights to the BH seed population and secular BH growth. To this end, we obtained near-infrared (NIR) spectroscopic observations of a sample of low-redshift bulgeless galaxies with mid-infrared colors suggestive of active galactic nuclei (AGNs). We find additional evidence of AGN activity (such as coronal lines and broad permitted lines) in 69% (9/13) of the sample, demonstrating that mid-infrared selection is a powerful tool to detect AGNs. More than half of the galaxies with confirmed AGN activity show fast outflows in [O III] in the optical and/or [Si VI] in the NIR, with the latter generally having much faster velocities that are also correlated to their spatial extent. We are also able to obtain virial BH masses for some targets and find they fall within the scatter of other late-type galaxies in the M BH-M stellar relation. The fact that they lack a significant bulge component indicates that secular processes, likely independent of major mergers, grew these BHs to supermassive sizes. Finally, we analyze the rotational gas kinematics and find two notable exceptions: two AGN hosts with outflows that appear to be rotating faster than expected. There is an indication that these two galaxies have stellar masses significantly lower than expected from their dark matter halo masses. This, combined with the observed AGN activity and strong gas outflows, may be evidence of the effects of AGN feedback.

Keywords: AGN host galaxies, Galaxy dark matter halos, Galaxy bulges, Galaxy nuclei, Seyfert galaxies, Active galactic nuclei, Near infrared astronomy
Electron Surfing Acceleration at Rippled Reconnection Fronts. The reconnection front (RF), one of the most efficient accelerators of particles in the terrestrial magnetosphere, is a sharp plasma boundary resulting from transient magnetic reconnection. It has been both theoretically predicted and observationally confirmed that electron-scale substructures can develop at the RFs. How such electron-scale structures modulate the electron energization and transport has not been fully explored. Based on high-resolution data from MMS spacecraft and particle tracing simulations, we investigate and compare the electron acceleration across two typical RFs with or without rippled electron-scale structures. Both observations and simulations reveal that high-energy electron flux behind the RF increases more dramatically if the electrons encounter a rippled RF surface, as compared to a smooth RF surface. The main acceleration mechanism is electron surfing acceleration, in which electrons are trapped by the ripples, due to the large local magnetic field gradient, and therefore undergo surfing motion along the motional electric field.

Keywords: Space plasmas, Interplanetary particle acceleration, Particle physics
The GALEX-PTF Experiment. II. Supernova Progenitor Radius and Energetics via Shock-cooling Modeling. The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early ultraviolet (UV) observations of core-collapse supernovae (CC SNe). We present the results from a simultaneous Galaxy Evolution Explorer (GALEX) and Palomar Transient Factory (PTF) search for early UV emission from SNe. We analyze five CC SNe for which we obtained near-UV (NUV) measurements before the first ground-based R-band detection. We introduce SOPRANOS, a new maximum likelihood fitting tool for models with variable temporal validity windows, and use it to fit the Sapir &amp; Waxman shock-cooling model to the data. We report four Type II SNe with progenitor radii in the range of R * ≈ 600-1100 R ⊙ and a shock velocity parameter in the range of v  s* ≈ 2700-6000 km s-1 (E/M ≈ 2-8 × 1050 erg/M ⊙) and one Type IIb SN with R * ≈ 210 R ⊙ and v  s* ≈ 11,000 km s-1 (E/M ≈ 1.8 × 1051 erg/M ⊙). Our pilot GALEX/PTF project thus suggests that a dedicated, systematic SN survey in the NUV band, such as the wide-field UV explorer ULTRASAT mission, is a compelling method to study the properties of SN progenitors and SN energetics.

Keywords: High energy astrophysics, Supernovae, Core-collapse supernovae
Local Spiral Structure Traced by Red Clump Stars. Using the cross-matched data of Gaia EDR3 and the Two Micron All Sky Survey Point Source Catalog, a sample of RC stars with parallax accuracies better than 20% is identified and used to reveal the nearby spiral pattern traced by old stars. As shown in the overdensity distribution of RC stars, there is an arc-like feature extending from l ~ 90° to ~243°, which passes close to the Sun. This feature is probably an arm segment traced by old stars, indicating the galaxy potential in the vicinity of the Sun. With a comparison to the spiral arms depicted by young objects, we found that there are considerable offsets between the two different components of the Galactic spiral arms. The spiral arm traced by RC stars tends to have a larger pitch angle, and hence a more loosely wound pattern.

Keywords: Galaxy structure, Galaxy stellar content, Solar neighborhood
A Very Long Baseline Array Trigonometric Parallax for RR Aql and the Mira Period-Luminosity Relation. We report Very Long Baseline Array observations of 22 GHz H2O and 43 GHz SiO masers toward the Mira variable RR Aql. By fitting the SiO maser emission to a circular ring, we estimate the absolute stellar position of RR Aql and find agreement with Gaia astrometry to within the joint uncertainty of ≈1 mas. Using the maser astrometry we measure a stellar parallax of 2.44 ± 0.07 mas, corresponding to a distance of ${410}_{-11}^{+12}$ pc. The maser parallax deviates significantly from the Gaia EDR3 parallax of 1.95 ± 0.11 mas, indicating a 3.8σ tension between radio and optical measurements. This tension is most likely caused by optical photocenter variations limiting the Gaia astrometric accuracy for this Mira variable. Combining infrared magnitudes with parallaxes for RR Aql and other Miras, we fit a period-luminosity relation using a Bayesian approach with Markov Chain Monte Carlo sampling and a strong prior for the slope of -3.60 ± 0.30 from the Large Magellanic Cloud. We find a K-band zero-point (defined at logP(days) = 2.30) of -6.79 ± 0.15 mag using very long baseline interferometry (VLBI) parallaxes and -7.08 ± 0.29 mag using Gaia parallaxes. The Gaia zero-point is statistically consistent with the more accurate VLBI value.

Keywords: Very long baseline interferometry, Distance indicators, Circumstellar masers, Mira variable stars, Annual parallax
The SDSS-HET Survey of Kepler Eclipsing Binaries. A Sample of Four Benchmark Binaries. The purpose of this work is to extend a sample of accurately modeled, benchmark-grade eclipsing binaries (EBs) with accurately determined masses and radii. We select four "well-behaved" Kepler binaries, KIC 2306740, KIC 4076952, KIC 5193386 and KIC 5288543, each with at least eight double-lined spectra from the Apache Point Observatory Galactic Evolution Experiment instrument that is part of the Sloan Digital Sky Surveys III and IV, and from the Hobby-Eberly High Resolution Spectrograph. We obtain masses and radii with uncertainties of 2.5% or less for all four systems. Three of these systems have orbital periods longer than 9 days, and thus populate an undersampled region of the parameter space for extremely well-characterized detached EBs. We compare the derived masses and radii against MESA MIST isochrones to determine the ages of the systems. All systems were found to be coeval, showing that the results are consistent across MESA MIST and PHOEBE.

Keywords: Binary stars, Close binary stars, Fundamental parameters of stars, Spectroscopic binary stars, Detached binary stars, Eclipsing binary stars
Sun-as-a-star Spectroscopic Observations of the Line-of-sight Velocity of a Solar Eruption on 2021 October 28. The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that Sun-as-a-star spectroscopic observations, together with imaging observations, could allow us to solve this problem. Using observations of the Extreme Ultraviolet Variability Experiment onboard the Solar Dynamics Observatory, we found clear blueshifted secondary emission components in extreme-ultraviolet spectral lines during a solar eruption on 2021 October 28. From simultaneous imaging observations, we found that the secondary components are caused by a mass ejection from the flare site. We estimated the line-of-sight (LOS) velocity of the ejecta from both the double Gaussian fitting method and the red-blue asymmetry analysis. The results of both methods agree well with each other, giving an average LOS velocity of the plasma of ∼423 km s−1. From the 304 Å image series taken by the Extreme ultraviolet Imager onboard the Solar Terrestrial Relation Observatory-A (STEREO-A) spacecraft, we estimated the plane-of-sky velocity from the STEREO-A viewpoint to be around 587 km s−1. The full velocity of the bulk motion of the ejecta was then computed by combining the imaging and spectroscopic observations, which turns out to be around 596 km s−1 with an angle of 42.°4 to the west of the Sun─Earth line and 16.°0 south to the ecliptic plane.

Keywords: Solar coronal mass ejections, Spectroscopy, Solar filament eruptions
Accretion Disk Outflow during the X-Ray Flare of the Super-Eddington Active Nucleus of I Zwicky 1. We present a detailed X-ray spectral analysis of the narrow-line Seyfert 1 galaxy I Zwicky 1, for which a sequence of X-ray flares were detected during a long, simultaneous observation acquired with XMM-Newton and NuSTAR. We determine the key parameters of the inner accretion disk and hot corona in the context of the disk reflection model, which successfully captures the evolution of the X-ray corona during the X-ray flare. Using a thermal Comptonization continuum model, we confirm that the corona rapidly cooled from ~200 to ~15 keV, likely a consequence of strong pair production and runaway in a disk-like corona during the X-ray flare, when the nonthermal electron fraction rapidly increased. We detect multiple variable blueshifted absorption features arising from outflowing material along the line of sight to I Zwicky 1, which we associated with ionized winds and ultrafast outflows. One of the ionized winds may be newly launched just after the X-ray flare. During the 5 days of NuSTAR observations, the ionization state and velocity of these outflows followed a relation of the form ξ ~ v  w  3.24, as expected from a super-Eddington wind. Comparison with molecular gas and warm ionized gas observations suggests that the kinematics of the ionized winds are consistent with a sufficiently cooled, momentum-driven outflow. Considering the dynamical feedback from these outflows can account for the significantly undermassive black hole in I Zwicky 1.

Keywords: Accretion, Active galaxies, Black holes, Quasars
A Detection of H<SUB>2</SUB> in a High-velocity Cloud toward the Large Magellanic Cloud. This work presents a new detection of H2 absorption arising in a high-velocity cloud associated with either the Milky Way or the Large Magellanic Cloud (LMC). The absorber was found in an archival Far Ultraviolet Spectroscopic Explorer spectrum of the LMC star Sk-70°32. This is the fifth well-characterized H2 absorber to be found in the Milky Way's halo and the second such absorber outside the Magellanic Stream and Bridge. The absorber has a local standard of rest central velocity of +140 km s-1 and a H2 column density of 1017.5 cm-2. It is most likely part of a cool and relatively dense inclusion (T ≈ 75 K, n H ~ 100 cm-3) in a warmer and more diffuse halo cloud. This halo cloud may be part of a still-rising Milky Way Galactic fountain flow or an outflow from the Large Magellanic Cloud.

Keywords: Molecular gas, High-velocity clouds, Interstellar absorption
The Imprint of Superradiance on Hierarchical Black Hole Mergers. Ultralight bosons are a proposed solution to outstanding problems in cosmology and particle physics: they provide a dark-matter candidate while potentially explaining the strong charge-parity problem. If they exist, ultralight bosons can interact with black holes through the superradiant instability. In this work we explore the consequences of this instability on the evolution of hierarchical black holes within dense stellar clusters. By reducing the spin of individual black holes, superradiance reduces the recoil velocity of merging binary black holes, which, in turn, increases the retention fraction of hierarchical merger remnants. We show that the existence of ultralight bosons with mass 2 × 10-14 ≲ μ/eV ≲ 2 × 10-13 would lead to an increased rate of hierarchical black hole mergers in nuclear star clusters. An ultralight boson in this energy range would result in up to ≈60% more present-day nuclear star clusters supporting hierarchical growth. The presence of an ultralight boson can also double the rate of intermediate-mass black hole mergers to ≈0.08 Gpc-3 yr-1 in the local universe. These results imply that a select range of ultralight boson masses can have far-reaching consequences for the population of black holes in dense stellar environments. Future studies into black hole cluster populations and the spin distribution of hierarchically formed black holes will test this scenario.

Keywords: Galaxy clusters, Intermediate-mass black holes, Dark matter, Astrophysical black holes
Grain Alignment in the Circumstellar Shell of IRC+10° 216. Dust-induced polarization in the interstellar medium (ISM) is due to asymmetric grains aligned with an external reference direction, usually the magnetic field. For both the leading alignment theories, the alignment of the grain's angular momentum with one of its principal axes and the coupling with the magnetic field requires the grain to be paramagnetic. Of the two main components of interstellar dust, silicates are paramagnetic, while carbon dust is diamagnetic. Hence, carbon grains are not expected to align in the ISM. To probe the physics of carbon grain alignment, we have acquired Stratospheric Observatory for Infrared Astronomy/Higch-resolution Airborne Wideband Camera-plus far-infrared photometry and polarimetry of the carbon-rich circumstellar envelope (CSE) of the asymptotic giant branch star IRC+10° 216. The dust in such CSEs are fully carbonaceous and thus provide unique laboratories for probing carbon grain alignment. We find a centrosymmetric, radial, polarization pattern, where the polarization fraction is well correlated with the dust temperature. Together with estimates of a low fractional polarization from optical polarization of background stars, we interpret these results to be due to a second-order, direct radiative external alignment of grains without internal alignment. Our results indicate that (pure) carbon dust does not contribute significantly to the observed ISM polarization, consistent with the nondetection of polarization in the 3.4 μm feature due to aliphatic CH bonds on the grain surface.

Keywords: Circumstellar dust, Magnetic fields, Carbonaceous grains, Asymptotic giant branch stars
z   2-9 Galaxies Magnified by the Hubble Frontier Field Clusters. I. Source Selection and Surface Density-Magnification Constraints from &gt;2500 Galaxies. We assemble a large comprehensive sample of 2534 z ~ 2, 3, 4, 5, 6, 7, 8, and 9 galaxies lensed by the six clusters from the Hubble Frontier Fields (HFF) program. Making use of the availability of multiple independent magnification models for each of the HFF clusters and alternatively treating one of the models as the "truth," we show that the median magnification factors from the v4 parametric models are typically reliable to values of 30-50, and in one case to 100. Using the median magnification factor from the latest v4 models, we estimate the UV luminosities of the 2534 lensed z ~ 2-9 galaxies, finding sources as faint as -12.4 mag at z ~ 3 and -12.9 mag at z ~ 7. We explicitly demonstrate the power of the surface density-magnification relations Σ(z) versus μ in the HFF clusters to constrain both distant galaxy properties and cluster lensing properties. Based on the Σ(z) versus μ relations, we show that the median magnification estimates from existing public models must be reliable predictors of the true magnification μ to μ &lt; 15 (95% confidence). We also use the observed Σ(z) versus μ relations to derive constraints on the evolution of the luminosity function faint-end slope from z ~ 7 to z ~ 2, showing that faint-end slope results can be consistent with blank-field studies if, and only if, the selection efficiency shows no strong dependence on the magnification factor μ. This can only be the case if very low-luminosity galaxies are very small, being unresolved in deep lensing probes.

Keywords: Galaxy clusters, Lyman-break galaxies, Strong gravitational lensing, Dwarf galaxies
Measuring the Properties of Active Galactic Nuclei Disks with Gravitational Waves. Active galactic nuclei (AGNs) are promising environments for the assembly of merging binary black hole (BBH) systems. Interest in AGNs as nurseries for merging BBHs is rising, following the detection of gravitational waves from a BBH system from the purported pair-instability mass gap, most notably GW190521. AGNs have also been invoked to explain the formation of the high-mass-ratio system GW190814. We draw on simulations of BBH systems in AGNs to propose a phenomenological model for the distribution of black hole spins of merging binaries in AGN disks. The model incorporates distinct features that make the AGN channel potentially distinguishable from other channels, such as assembly in the field and in globular clusters. The model parameters can be mapped heuristically to the age and density of the AGN disks. We estimate the extent to which different populations of mergers in AGNs can be distinguished. If the majority of merging black holes are assembled in AGNs, future gravitational-wave observations may provide insights into the dynamics of AGN disks.

Keywords: Bayesian statistics, Active galactic nuclei, Gravitational waves
Characterizing the Variable X-Ray and UV-Optical Flux Behavior of Blazars. The variability of blazars in the X-ray and optical regions both informs the physics of their emitting region and places demands on the observer if a program requires that the object be bright or faint. The extensive simultaneous X-ray and optical observation by the Neil Gehrels Swift Observatory (Swift) provides the best insight into the variable nature of these objects. This program uses Swift data for 19 X-ray-bright blazars, generally at z &gt; 0.1, to determine their variability properties. The analysis is based on structure functions and provides insight into the nature of the variability and how it depends on time, luminosity, and redshift. We also consider strategies for observing blazars at or above average brightness, given a time delay between planning an observation and obtaining the data. This is critical to observations with orbiting X-ray telescopes, current or future. The variability in the soft X-ray band is typically three to eight times larger than at UV-optical wavelengths, at fixed time differences (i.e., 30 or 100 days). There is almost no difference in the amplitude of variation (X-ray or UV-optical) as a function of redshift (time delay of 30 days) and a modest positive correlation with luminosity. In the X-ray band, blazars that become brighter than normal typically remain bright for at least 2-3 months, although with significant flickering. One can avoid observing objects that are significantly below the average X-ray flux by scheduling the observation when F X &gt; 0.9F X,avg, which requires monitoring observations near the time of the scheduling activity.

Keywords: Hot intergalactic medium, Blazars, X-ray active galactic nuclei, X-ray telescopes
Compact Object Modeling in the Globular Cluster 47 Tucanae. The globular cluster 47 Tucanae (47 Tuc) is one of the most massive star clusters in the Milky Way and is exceptionally rich in exotic stellar populations. For several decades it has been a favorite target of observers, and yet it is computationally very challenging to model because of its large number of stars (N ≳ 106) and high density. Here we present detailed and self-consistent 47 Tuc models computed with the Cluster Monte Carlo code (CMC). The models include all relevant dynamical interactions coupled to stellar and binary evolution, and reproduce various observations, including the surface brightness and velocity dispersion profiles, pulsar accelerations, and numbers of compact objects. We show that the present properties of 47 Tuc are best reproduced by adopting an initial stellar mass function that is both bottom-heavy and top-light relative to standard assumptions (as in, e.g., Kroupa 2001), and an initial Elson profile (Elson et al. 1987) that is overfilling the cluster's tidal radius. We include new prescriptions in CMC for the formation of binaries through giant star collisions and tidal captures, and we show that these mechanisms play a crucial role in the formation of neutron star binaries and millisecond pulsars in 47 Tuc; our best-fit model contains ~50 millisecond pulsars, 70% of which are formed through giant collisions and tidal captures. Our models also suggest that 47 Tuc presently contains up to ~200 stellar-mass black holes, ~5 binary black holes, ~15 low-mass X-ray binaries, and ~300 cataclysmic variables.

Keywords: Brown dwarfs, N-body simulations, Compact objects, Star clusters
Dependence of Dust Formation on the Supernova Explosion. We investigate the properties, composition, and dynamics of dust formation and growth for a diverse set of core-collapse supernovae (CCSNe), with 15, 20, and 25 M ⊙ progenitor masses, explosion energies ranging from 0.5 to 120 foe, and varied engine type. These explosions are evolved with a 1D Lagrangian hydrodynamics code out to a minimum of 1157 days to model the ejecta as it expands and cools. A multigrain dust nucleation and growth model is applied to these results. We find that higher explosion energies lead to an earlier onset of dust formation, smaller grain sizes, and larger silicate abundances. Further, we see that nuclear burning during the explosion leads to enhanced formation of silicate dust. Finally, we build composite models from our suite to predict the efficiency of CCSN dust production as a function of metallicity.

Keywords: Astrophysical dust processes, Core-collapse supernovae
On the Dayside Atmosphere of WASP-12b. The atmospheric structure of WASP-12b has been hotly contested for years, with disagreements on the presence of a thermal inversion as well as the carbon-to-oxygen ratio, C/O, due to retrieved abundances of H2O, CO2, and other included species such as HCN and C2H2. Previously, these difficult-to-diagnose discrepancies have been attributed to model differences; assumptions in these models were thought to drive retrievals toward different answers. Here, we show that some of these differences are independent of model assumptions and are instead due to subtle differences in the inputs, such as the eclipse depths and line-list databases. We replicate previously published retrievals and find that the retrieved results are data driven and are mostly unaffected by the addition of species such as HCN and C2H2. We also propose a new physically motivated model that takes into consideration the formation of H- via the thermal dissociation of H2O and H2 at the temperatures reached in the dayside atmosphere of WASP-12b, but the data's current resolution does not support its inclusion in the atmospheric model. This study raises the concern that other exoplanet retrievals may be similarly sensitive to slight changes in the input data.

Keywords: Exoplanet atmospheric composition , Exoplanets, Hot Jupiters, Exoplanet systems, Exoplanet astronomy, Exoplanet atmospheres