Sazuna/UAT_keywords huggingface dataset:
Consistent Calibration of the Tip of the Red Giant Branch in the Large Magellanic Cloud on the Hubble Space Telescope Photometric System and a Redetermination of the Hubble Constant. We present a calibration of the tip of the red giant branch (TRGB) in the Large Magellanic Cloud (LMC) on the Hubble Space Telescope (HST)/ACS F814W system. We use archival HST observations to derive blending corrections and photometric transformations for two ground-based wide-area imaging surveys of the Magellanic Clouds. We show that these surveys are biased bright by up to ∼0.1 mag in the optical due to blending, and that the bias is a function of local stellar density. We correct the LMC TRGB magnitudes from Jang &amp; Lee and use the geometric distance from Pietrzyński et al. to obtain an absolute TRGB magnitude of {M}{{F}814{{W}}}=-3.97+/- 0.046 {mag}. Applying this calibration to the TRGB magnitudes from Freedman et al. in SN Ia hosts yields a value for the Hubble constant of H 0 = 72.4 ± 2.0 km s-1 Mpc-1 for their TRGB+SNe Ia distance ladder. The difference in the TRGB calibration and the value of H 0 derived here and by Freedman et al. primarily results from their overestimate of the LMC extinction, caused by inconsistencies in their different sources of TRGB photometry for the Magellanic Clouds. Using the same source of photometry (OGLE) for both Clouds and applying the aforementioned corrections yields a value for the LMC I-band TRGB extinction that is lower by 0.06 mag, consistent with independent OGLE reddening maps used by us and by Jang &amp; Lee to calibrate TRGB and determine H 0.

Keywords: Cosmology, Hubble Space Telescope, Small Magellanic Cloud, Large Magellanic Cloud, Distance indicators
On the Dust Signatures Induced by Eccentric Super-Earths in Protoplanetary Disks. We investigate the impact of a highly eccentric 10 M ⊕ (where M ⊕ is the Earth mass) planet embedded in a dusty protoplanetary disk on dust dynamics and its observational implications. By carrying out high-resolution 2D gas and dust two-fluid hydrodynamical simulations, we find that the planet’s orbit can be circularized at large radii. After the planet’s orbit is circularized, partial gap opening and dust ring formation happen close to the planet’s circularization radius, which can explain the observed gaps/rings at the outer region of disks. When the disk mass and viscosity become low, we find that an eccentric planet can even open gaps and produce dust rings close to the pericenter and apocenter radii before its circularization. This offers alternative scenarios for explaining the observed dust rings and gaps in protoplanetary disks. A lower disk viscosity is favored to produce brighter rings in observations. An eccentric planet can also potentially slow down the dust radial drift in the outer region of the disk when the disk viscosity is low (α ≲ 2 × 10-4) and the circularization is faster than the dust radial drift.

Keywords: Accretion, Exoplanet dynamics, Exoplanets, Dust continuum emission, Protoplanetary disks
Antlia 2’s Role in Driving the Ripples in the Outer Gas Disk of the Galaxy. We employ the earlier published proper motions of the newly discovered Antlia 2 dwarf galaxy derived from Gaia data to calculate its orbital distribution in the cosmologically recent past. Using these observationally motivated orbits, we calculate the effect of the Antlia 2 dwarf galaxy on the outer H I disk of the Milky Way, using both test particle and smoothed particle hydrodynamics simulations. We find that orbits with low pericenters, ∼10 kpc, produce disturbances that match the observed outer H I disk perturbations. We have independently recalculated the proper motion of the Antlia 2 dwarf from Gaia data and found a proper motion of (μ  α cosδ, μ  δ ) = (-0.068, 0.032) ± (0.023, -0.031) mas yr-1, which agrees with results from Torrealba et al. within the errors, but gives lower mean pericenters, e.g., ∼15 kpc for our fiducial model of the Milky Way. We also show that the Sagittarius dwarf galaxy interaction does not match the observed perturbations in the outer gas disk. Thus, Antlia 2 may be the driver of the observed large perturbations in the outer gas disk of the Galaxy. The current location of the Antlia 2 dwarf galaxy closely matches that predicted by an earlier dynamical analysis of the dwarf galaxy that drove ripples in the outer Galaxy, and, in particular, its orbit is nearly coplanar to the Galactic disk. If the Antlia 2 dwarf galaxy is responsible for the perturbations in the outer Galactic disk, it would have a specific range of proper motions that we predict here; this can be tested soon with Gaia DR-3 and Gaia DR-4 data.

Keywords: Cosmology, Dark matter, Galaxies, Galactic and extragalactic astronomy
Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia. In astrometric binaries, the presence of a dark, unseen star can be inferred from the gravitational pull it induces on its luminous binary companion. While the orbit of such binaries can be characterized with precise astrometric measurements, constraints made from astrometry alone are not enough to measure the component masses. In this work, we determine the precision with which Gaia can astrometrically measure the orbits and—with additional observations—the component masses, for luminous stars hosting hidden companions. Using realistic mock Gaia observations, we find that Gaia can precisely measure the orbits of binaries hosting hidden brown dwarfs out to tens of parsecs and hidden white dwarf and neutron star companions at distances as far as several hundred parsecs. Heavier black hole companions may be measured out to 1 kpc or farther. We further determine how orbital period affects this precision, finding that Gaia can characterize orbits with periods as short as 10 days and as long as a few 103 days, with the best measured orbits having periods just short of Gaia’s mission lifetime. Extending Gaia’s nominal five-year mission lifetime by an additional five years not only allows for the measurement of longer period orbits, but those longer period binaries can be seen at even greater distances.

Keywords: Neutron stars, Black hole physics, Astrometric binary stars, Space astrometry
A Versatile and Accurate Method for Halo Mass Determination from Phase-space Distribution of Satellite Galaxies. We propose a versatile and accurate method to estimate the halo mass and concentration from the kinematics of satellite galaxies. We construct the 6D phase-space distribution function of satellites from a cosmological simulation based on the similarity of internal dynamics for different halos. Within the Bayesian statistical framework, not only can we efficiently infer the halo mass and concentration, we can also treat various observational effects, including the selection function, incomplete data, and measurement errors, in a rigorous and straightforward manner. Through tests with mock samples, we show that our method is valid and accurate, as well as more precise than pure steady-state methods. It can constrain the halo mass to within ∼20% using only 20 tracers and has a small intrinsic uncertainty of ∼10%. In addition to the clear application to the Milky Way and similar galaxies, our method can be extended to galaxy groups or clusters.

Keywords: Galaxy clusters, Galaxy dark matter halos, Milky Way dark matter halo, Bayesian statistics, Galaxy dynamics, Galaxy mass distribution, Galaxy kinematics, Galaxy groups, Galaxy masses, Astronomical simulations
An Empirical Model of Energetic Neutral Atom Imaging of the Heliosphere and Its Implications for Future Heliospheric Missions at Great Heliocentric Distances. Several concepts for heliospheric missions operating at heliocentric distances far beyond Earth orbit are currently investigated by the scientific community. The mission concept of the Interstellar Probe, e.g., aims at reaching a distance of 1000 au away from the Sun within this century. This would allow the coming generation to obtain a global view of our heliosphere from an outside vantage point by measuring the energetic neutral atoms (ENAs) originating from the various plasma regions. It would also allow for direct sampling of the unperturbed interstellar medium, as well as for many observation opportunities beyond heliospheric science, such as visits to Kuiper Belt objects, a comprehensive view on the interplanetary dust populations, and infrared astronomy free from the foreground emission of the zodiacal cloud. In this study, we present a simple empirical model of ENAs from the heliosphere and derive basic requirements for ENA instrumentation on board a spacecraft at great heliocentric distances. We consider the full energy range of heliospheric ENAs from 10 eV to 100 keV because each part of the energy spectrum has its own merits for heliospheric science. To cover the full ENA energy range, two or three different ENA instruments are needed. Thanks to parallax observations, some insights about the nature of the IBEX ribbon and the dimensions of the heliosphere can already be gained by ENA imaging from a few au heliocentric distance. To directly reveal the global shape of the heliosphere, measurements from outside the heliosphere are, of course, the best option.

Keywords: Space plasmas, Deep space probes, Astrosphere interstellar medium interactions, Heliosphere, Heliosheath
Calibrating the Cosmic Distance Ladder Using Gravitational-wave Observations. Type Ia supernovae (SNe Ia) are among the pre-eminent distance ladders for precision cosmology due to their intrinsic brightness, which allows them to be observable at high redshifts. Their usefulness as unbiased estimators of absolute cosmological distances, however, depends on accurate understanding of their intrinsic brightness, or anchoring their distance scale. This knowledge is based on calibrating their distances with Cepheids. Gravitational waves from compact binary coalescences, being standard sirens, can be used to validate distances to SNe Ia when both occur in the same galaxy or galaxy cluster. The current measurement of distance by the advanced LIGO and Virgo detector network suffers from large statistical errors (∼50%). However, we find that, using a third-generation gravitational-wave detector network, standard sirens will allow us to measure distances with an accuracy of ∼0.1%-3% for sources within ≤300 Mpc. These are much smaller than the dominant systematic error of ∼5% due to the radial peculiar velocity of host galaxies. Therefore, gravitational-wave observations could soon add a new cosmic distance ladder for an independent calibration of distances to SNe Ia.

Keywords: Cosmology, Galaxy clusters, Type Ia supernovae, Gravitational waves
Tidally Induced Radius Inflation of Sub-Neptunes. Recent work suggests that many short-period super-Earth and sub-Neptune planets may have significant spin axis tilts (“obliquities”). When planets are locked in high-obliquity states, the tidal dissipation rate may increase by several orders of magnitude. This intensified heat deposition within the planets’ interiors should generate significant structural consequences, including atmospheric inflation leading to larger transit radii. Using up-to-date radius estimates from Gaia Data Release 2, we show evidence for ∼50% larger average radii of planets wide of first-order mean-motion resonances, a population of planets with a theorized frequent occurrence of high obliquities. We investigate whether this radius trend could be a signature of obliquity tides. Using an adaptation of the Modules for Experiments in Stellar Astrophysics (MESA) stellar evolution toolkit, we model the atmospheric evolution of sub-Neptune-mass planets in response to additional internal heat from obliquity tides. The degree of radius inflation predicted by the models is ∼10%-100% for tidal luminosities ≳10-5 of the incident stellar power; this degree of inflation is broadly consistent with the observations and can approximately be described by power-law relationships. We present a few case studies of very low density “super-puff” planets—Kepler-79 d, Kepler-31 c, and Kepler-27 b—and show that they are strong candidates for potentially having undergone tidally induced radius inflation. We also discuss how the discrepancy between the two populations of planets with masses derived from radial velocities and transit timing variations is connected to the radius distribution features we have identified. Altogether, the calculations in this work confirm that tidal dissipation has nonnegligible consequences for the structural properties of short-period sub-Neptunes.

Keywords: Exoplanets, Super Earths, Exoplanet astronomy, Atmospheric tides, Exoplanet tides, Exoplanet structure, Mini Neptunes, Exoplanet atmospheres
Galactic Winds in Low-mass Galaxies. Stellar-feedback-driven outflows are predicted to play a fundamental role in the baryon cycle of low-mass galaxies. However, observational constraints of winds in nearby dwarf galaxies are limited, as outflows are transient, intrinsically low surface brightness features and thus difficult to detect. Using deep Hα observations, we search for winds in a sample of 12 nearby dwarfs (M * ∼ 107-109.3 M ⊙) that host ongoing or recent starbursts. We detect features that we classify as winds in six galaxies, fountain candidates in five galaxies, and diffuse interstellar medium (ISM) in one system. Winds are found preferentially in galaxies with centrally concentrated star formation, while fountains are found in galaxies with spatially distributed star formation. We suggest that the concentration of star formation is a predictor for whether a low-mass galaxy will develop a wind. The spatial extent of all detected ionized gas is limited (&lt;1/10 virial radius) and would still be considered the ISM by cosmological simulations. Our observations suggest that the majority of material expelled from dwarfs does not escape to the intergalactic medium but remains in the halo and may be recycled to the galaxies. Derived mass-loading factors range from 0.2 to 7 (with only a weak dependency on circular velocity or stellar mass), in tension with higher values in simulations needed to reproduce realistic low-mass galaxies and resolve discrepancies with ΛCDM. The sample is part of the panchromatic STARBurst IRegular Dwarf Survey—STARBIRDS—designed to characterize the starburst phenomenon in dwarf galaxies. We also report a previously uncatalogued nearby galaxy (J1118+7913).

Keywords: Dwarf irregular galaxies, Galactic winds, Galaxy evolution, Circumgalactic medium
Search for Gravitational-wave Signals Associated with Gamma-Ray Bursts during the Second Observing Run of Advanced LIGO and Advanced Virgo. We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of &lt;9.38 × 10-6 (modeled) and 3.1 × 10-4 (unmodeled). We do not find any significant evidence for gravitational-wave signals associated with the other gamma-ray bursts analyzed, and therefore we report lower bounds on the distance to each of these, assuming various source types and signal morphologies. Using our final modeled search results, short gamma-ray burst observations, and assuming binary neutron star progenitors, we place bounds on the rate of short gamma-ray bursts as a function of redshift for z ≤ 1. We estimate 0.07-1.80 joint detections with Fermi-GBM per year for the 2019-20 LIGO-Virgo observing run and 0.15-3.90 per year when current gravitational-wave detectors are operating at their design sensitivities.

Keywords: Gamma-ray bursts, High energy astrophysics, Gravitational wave sources, Gravitational wave astronomy, Burst astrophysics, Gravitational waves, LIGO
The Virgo Overdensity Explained. We suggest that the Virgo Overdensity of stars in the stellar halo is the result of a radial dwarf galaxy merger that we call the Virgo Radial Merger. Because the dwarf galaxy passed very near to the Galactic center, the debris has a large range of energies but nearly zero L  z  angular momentum. The debris appears to extend from 5 to 50 kpc from the Sun in the Virgo region. We connect different moving groups of this merger debris to the Perpendicular and Parallel Streams (the Virgo Stellar Stream is associated with either or both of these streams), the Hercules-Aquila Cloud, and possibly the Eridanus-Phoenix Overdensity. This radial merger can explain the majority of the observed moving groups of RR Lyrae and blue horizontal branch stars that have previously been identified in Virgo. This merger also produces debris in the solar neighborhood similar to that identified as the Gaia-Enceladus merger or Gaia sausage. Orbits are provided for components of the Virgo Radial Merger progenitor and debris that appears to be related to the Cocytos Stream, which was also recovered in the Virgo region.

Keywords: Astronomy data analysis
Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets around Low-mass Stars: GJ 832, GJ 176, and GJ 436. Correct estimates of stellar extreme ultraviolet (EUV; 100-1170 Å) flux are important for studying the photochemistry and stability of exoplanet atmospheres, as EUV radiation ionizes hydrogen and contributes to the heating, expansion, and potential escape of a planet’s upper atmosphere. Contamination from interstellar hydrogen makes observing EUV emission from M stars particularly difficult, and impossible past 100 pc, and necessitates other means to predict the flux in this wavelength regime. We present EUV-infrared (100 Å-5.5 μm) synthetic spectra computed with the PHOENIX atmospheric code of three early M dwarf planet hosts: GJ 832 (M1.5 V), GJ 176 (M2.5 V), and GJ 436 (M3.5 V). These one-dimensional, semi-empirical, non-local thermodynamic equilibrium models include simple temperature prescriptions for the stellar chromosphere and transition region, from where ultraviolet (100-3008 Å) fluxes originate. We guide our models with Hubble Space Telescope far- and near-UV spectra and discuss the ability to constrain these models using Galaxy Evolution Explorer UV photometry. Our models closely reproduce the observations and predict the unobservable EUV spectrum at a wavelength resolution of &lt;0.1 Å. The temperature profiles that best reproduce the observations for all three stars are described by nearly the same set of parameters, suggesting that early M-type stars may have similar thermal structures in their upper atmospheres. With an impending UV observation gap and the scarcity of observed EUV spectra for stars less luminous and more distant than the Sun, upper atmosphere models such as these are important for providing realistic spectra across short wavelengths and for advancing our understanding of the effects of radiation on planets orbiting M stars.

Keywords: Ultraviolet astronomy, M dwarf stars, Stellar chromospheres, Stellar activity
Clustering of Lyα Emitters around Quasars at z ∼ 4. The strong observed clustering of z &gt; 3.5 quasars indicates that they are hosted by massive ({M}halo}≳ {10}12 {h}-1 {M}☉ ) dark matter halos. Assuming that quasars and galaxies trace the same large-scale structures, this should manifest as strong clustering of galaxies around quasars. Previous works on high-redshift quasar environments have failed to find convincing evidence for these overdensities. Here we conduct a survey for Lyα emitters (LAEs) in the environs of 17 quasars at z ∼ 4 probing scales of R≲ 7 {h}-1 {Mpc}. We measure an average LAE overdensity of {1.4}-0.4+0.4, which we quantify by fitting the quasar-LAE cross-correlation function. We find consistency with a power-law shape with correlation length {r}0{QG}={2.78}-1.05+1.16 {h}-1 {cMpc} for a fixed slope of γ = 1.8 and rule out a zero clustering hypothesis at the 95% confidence level. We also measure the LAE autocorrelation length and find {r}0{GG}={9.12}-1.31+1.32 {h}-1 cMpc (γ = 1.8), which is {3.3}-1.0+0.9 times higher than the value measured in blank fields. Taken together, our results clearly indicate that LAEs are significantly clustered around z ∼ 4 quasars. We compare the observed clustering with the expectation from a deterministic bias model, whereby LAEs and quasars probe the same underlying dark matter overdensities, and find that our measurements fall short of the predicted overdensities by a factor of {2.1}-0.5+0.7. We discuss possible explanations for this discrepancy, including large-scale quenching or the presence of excess dust in galaxies near quasars. Finally, the large cosmic variance from field to field observed in our sample (10/17 fields are actually underdense) cautions one from overinterpreting studies of z ∼ 6 quasar environments based on a single or handful of quasar fields. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile. Data obtained from the ESO Archive, Normal program, service mode. Program ID: 094.A-0900.

Keywords: Cosmology, Early universe, Quasar-galaxy pairs, Large-scale structure of the universe, Non-thermal radiation sources, Clustering, Lyman-alpha galaxies, High-redshift galaxies
The Most Massive Galaxies with Large Depleted Cores: Structural Parameter Relations and Black Hole Masses. Luminous spheroids (M  V  ≲ -21.50 ± 0.75 mag) contain partially depleted cores with sizes (R b) typically 0.02-0.5 kpc. However, galaxies with R b &gt; 0.5 kpc are rare and poorly understood. Here, we perform detailed decompositions of the composite surface brightness profiles, extracted from archival Hubble Space Telescope and ground-based images, of 12 extremely luminous “large-core” galaxies that have R b &gt; 0.5 kpc and M  V  ≲ -23.50 ± 0.10 mag, fitting a core-Sérsic model to the galaxy spheroids. Using 28 “normal-core” (i.e., R b &lt; 0.5 kpc) galaxies and one “large-core” (i.e., R b &gt; 0.5 kpc) galaxy from the literature, we constructed a final sample of 41 core-Sérsic galaxies. We find that large-core spheroids (with stellar masses M * ≳ 1012 M ⊙) are not simple high-mass extensions of the less luminous normal-core spheroids having M * ∼ 8 × 1010-1012 M ⊙. While the two types follow the same strong relations between the spheroid luminosity L  V  and R b ({R}{{b}}\propto {L}V1.38+/- 0.13), and the spheroid half-light radius R e ({R}{{e}}\propto {L}V1.08+/- 0.09, for ellipticals plus Brightest Cluster Galaxies), we discover a break in the core-Sérsic σ-L  V  relation occurring at M  V  ∼ -23.50 ± 0.10 mag. Furthermore, we find a strong log-linear R b-M BH relation for the 11 galaxies in the sample with directly determined supermassive black hole (SMBH) masses M BH—3/11 galaxies are large-core galaxies—such that {R}{{b}}\propto {M}BH}0.83+/- 0.10. However, for the large-core galaxies the SMBH masses estimated from the M BH-σ and core-Sérsic M BH-L relations are undermassive, by up to a factor of 40, relative to expectations from their large R b values, confirming earlier results. Our findings suggest that large-core galaxies harbor overmassive SMBHs (M BH ≳ 1010 M ⊙), considerably (∼3.7-15.6σ and ∼0.6-1.7σ) larger than expectations from the spheroid σ and L, respectively. We suggest that the R b-M BH relation can be used to estimate SMBH masses in the most massive galaxies.

Keywords: Lenticular galaxies, Supermassive black holes, cD galaxies, Galaxy structure, Galaxy nuclei, Galaxy photometry, Elliptical galaxies