Sazuna/UAT_keywords huggingface dataset:
Kinematics of the Circumgalactic Medium of a z = 0.77 Galaxy from Mg II Tomography. Galaxy evolution is thought to be driven in large part by the flow of gas between galaxies and the circumgalactic medium (CGM), a halo of metal-enriched gas extending out to ≳100 kpc from each galaxy. Studying the spatial structure of the CGM holds promise for understanding these gas flow mechanisms; however, the common method of using background quasar sight lines provides minimal spatial information. Recent works have shown the utility of extended background sources such as giant gravitationally lensed arcs. Using background lensed arcs from the CSWA 38 lens system, we continuously probed, at a resolution element of about 15 kpc2, the spatial and kinematic distribution of Mg II absorption in a star-forming galaxy at z = 0.77 (stellar mass ≈109.7 M⊙, star formation rate ≈10 M⊙ yr-1) at impact parameters D ≃ 5-30 kpc. Our results present an anisotropic, optically thick medium whose absorption strength decreases with increasing impact parameter, in agreement with the statistics toward quasars and other gravitational arcs. Furthermore, we find generally low line-of-sight velocities in comparison to the relatively high velocity dispersion in the Mg II gas (with typical σ ≈ 50 km s-1). While the galaxy itself exhibits a clear outflow (with Mg II velocities up to ~500 km s-1) in the down-the-barrel spectrum, the outflow component is subdominant and only weakly detected at larger impact parameters probed by the background arcs. Our results provide evidence of mainly dispersion-supported, metal-enriched gas recycling through the CGM.

Keywords: Galaxy fountains, Galaxy formation, Interstellar absorption, Galaxy winds, Circumgalactic medium
A Multi-instrument Study of the 2018 Hard-state-only Outburst of H1743-322. Distinct changes of the spectral and variability properties observed in black hole transients during a bright outburst deliver insight into the evolution of the accretion flow and accretion geometry. We investigated NICER and Swift monitoring observations of H 1743-322 during its 2018 outburst as well as NuSTAR and XMM-Newton data. The observed hardness ratios, rms amplitudes, and properties of quasiperiodic oscillations indicate that H 1743-322 showed another hard-state-only, or so-called "failed", outburst. The energy spectra obtained from NuSTAR and XMM-Newton data confirm the hard-state nature and give photon indices of ~1.7, typically found in the hard state of H 1743-322. The NICER monitoring observations allow us to follow the evolution of covariance ratios during a hard-state-only outburst of H 1743-322 for the first time. We confirm that the presence of flat covariance ratios at low energies is established early in the outburst and find that this shape is maintained throughout the outburst.

Keywords: Close binary stars, Transient sources, Stellar mass black holes, Low-mass x-ray binary stars, Time series analysis
Modified Gravity and the Flux-weighted Gravity-Luminosity Relationship of Blue Supergiant Stars. We calculate models of stellar evolution for very massive stars and include the effects of modified gravity to investigate the influence on the physical properties of blue supergiant stars and their use as extragalactic distance indicators. With shielding and fifth force parameters in a similar range as those in previous studies of Cepheid and tip of the red giant branch (TRGB) stars, we find clear effects on stellar luminosity and flux-weighted gravity. The relationship between flux-weighted gravity, gF ≡ g/ ${T}_{\mathrm{eff}}^{4}$ , and bolometric magnitude Mbol, which has been used successfully for accurate distance determinations, is systematically affected. While the stellar evolution of flux-weighted gravity-luminosity relationships (FGLRs) show a systematic offset from the observed relation, we can use the differential shifts between models with Newtonian and modified gravity to estimate the influence on FGLR distance determinations. Modified gravity leads to an increase in distance of 0.05-0.15 magnitudes in distance modulus. These changes are comparable to the ones found for Cepheid stars. We compare observed FGLR and TRGB distances of nine galaxies to constrain the free parameters of modified gravity. Not accounting for systematic differences between TRGB and FGLR distances shielding parameters of 5 × 10-7 and 10-6 and fifth force parameters of 1/3 and 1 can be ruled out with about 90% confidence. Allowing for potential systematic offsets between TRGB and FGLR distances no determination is possible for a shielding parameter of 10-6. For 5 × 10-7 a fifth force parameter of 1 can be ruled out to 92% but 1/3 is unlikely only to 60%.

Keywords: Galactic and extragalactic astronomy, Stellar physics, Non-standard theories of gravity, Distance indicators
A Layered Debris Disk around M Star TWA 7 in Scattered Light. We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the Space Telescope Imaging Spectrograph (STIS) instrument in visible light. Together with archival observations, including HST/NICMOS using the F160W filter and Very Large Telescope/SPHERE at the H-band in polarized light, we investigate the system in scattered light. By studying this nearly face-on system using geometric disk models and Henyey-Greenstein phase functions, we report a new discovery of a tertiary ring and a clump. We identify a layered architecture: three rings, a spiral, and an ≍150 au2 elliptical clump. The most extended ring peaks at 28 au, and the other components are on its outskirts. Our point-source detection-limit calculations demonstrate the necessity of disk modeling in imaging fainter planets. Morphologically, we witness a clockwise spiral motion, and the motion pattern is consistent with both solid body motion and local Keplerian motion; we also observe underdensity regions for the secondary ring that might result from mean-motion resonance or moving shadows: both call for re-observations to determine their nature. Comparing multi-instrument observations, we obtain blue STIS-NICMOS color, a STIS-SPHERE radial distribution peak difference for the tertiary ring, and a high SPHERE-NICMOS polarization fraction; these aspects indicate that TWA 7 could retain small dust particles. By viewing the debris disk around M star TWA 7 at a nearly face-on vantage point, our study allows for the understanding of such disks in scattered light in both system architecture and dust property.

Keywords: Planetary system formation, Coronagraphic imaging, Debris disks, Orbital motion
Emergent Gravity Fails to Explain Color-dependent Galaxy-Galaxy Lensing Signal from SDSS DR7. We test Verlinde's Emergent Gravity (EG) theory using a galaxy-galaxy lensing technique based on Sloan Digital Sky Survey DR7 data. In the EG scenario, we do not expect a color dependence of the galaxy sample in the apparent dark matter predicted by EG, which is exerted only by the baryonic mass. If the baryonic mass is similar, then the predicted lensing profiles from the baryonic mass should be similar according to EG, regardless of the color of the galaxy sample. We use the stellar mass of the galaxy as a proxy of its baryonic mass. We divide our galaxy sample into five stellar mass bins, and further classify them as red and blue subsamples in each stellar mass bin. If we set the halo mass and concentration as free parameters, ΛCDM is favored by our data in terms of the reduced χ2, while EG fails to explain the color dependence of the excess surface density from the galaxy-galaxy lensing measurement.

Keywords: Weak gravitational lensing, Quantum gravity
Improving NASA/IPAC Extragalactic Database Redshift Calculations. The NASA/IPAC Extragalactic Database (NED) is an impressive tool for finding near-exhaustive information on millions of astrophysical objects. Here, we outline a small systematic error that occurs in NED because a low-redshift approximation is used when making the correction from redshifts in the heliocentric frame to the cosmic microwave background (CMB) rest frame. It means that historically NED systematically misreported the values of CMB-frame redshifts by up to ~10-3z (about 0.001 at redshift of 1). This is a systematic error, and therefore the impact on applications requiring precise redshifts has the potential to be significant-for example, a systematic redshift error of ~10-4 at low redshift could resolve the Hubble tension. We have consulted with the NED team and they are updating the software to remove this systematic error so these corrections are accurate at all redshifts. Here, we explain the changes and how they impact the redshift values NED currently reports.

Keywords: Cosmology, Astronomy databases, Galaxies
Metastable Helium Absorptions with 3D Hydrodynamics and Self-consistent Photochemistry. I. WASP-69b, Dimensionality, X-Ray and UV Flux Level, Spectral Types, and Flares. The metastable helium (He*) lines near 10830 Å are ideal probes of atmospheric erosion-a common phenomenon of close-in exoplanet evolution. A handful of exoplanet observations yielded well-resolved He* absorption features in transits, yet they were mostly analyzed with 1D isothermal models prescribing mass-loss rates. This work devises 3D hydrodynamics coevolved with ray-tracing radiative transfer and nonequilibrium thermochemistry. Starting from the observed stellar/planetary properties with reasonable assumptions about the host's high-energy irradiation, we predict from first principles the mass-loss rate, the temperature and ionization profiles, and 3D outflow kinematics. Our simulations well reproduce the observed He* line profiles and light curves of WASP-69b. We further investigate the dependence of He* observables on simulation conditions and host radiation. The key findings are as follows: (1) Simulations reveal a photoevaporative outflow (~0.55 M⊕ Gyr-1 ≃ 1011 g s-1) for WASP-69b without a prominent comet-like tail, consistent with the symmetric transit shape. (2) 3D simulations are mandatory for hydrodynamic features, including Coriolis force, advection, and kinematic line broadening. (3) EUV (&gt;13.6 eV) photons dominate photoevaporative outflows and populate He* via recombination; FUV is also detrimental by destroying He*; X-ray plays a secondary role. (4) K stars hit the sweet spot of EUV/far-UV balance for He* line observation, while G and M stars are also worthy targets. (5) Stellar flares create characteristic responses in the He* line profiles.

Keywords: Hydrodynamical simulations, Hydrodynamics, Astronomical simulations, Astrochemistry, Exoplanet astronomy, Exoplanet evolution, Exoplanet atmospheres
Metastable Helium Absorptions with 3D Hydrodynamics and Self-consistent Photochemistry. II. WASP-107b, Stellar Wind, Radiation Pressure, and Shear Instability. This paper presents simulations of the metastable helium (He*) observations of WASP-107b, so far the highest signal-to-noise ratio detection that is confirmed by three different instruments. We employ full 3D hydrodynamics coupled with coevolving nonequilibrium thermochemistry and ray-tracing radiation, predicting mass-loss rates, temperature profiles, and synthetic He* line profiles and light curves from first principles. We find that a stellar wind stronger than solar is demanded by the observed heavily blueshifted line profile and asymmetric transit light curve. Radiation pressure can be important for Lyα observations, but not He*. Our model finds that WASP-107b is losing mass at a rate of $\dot{M}\simeq 1.0\times {10}^{-9}\,{M}_{\oplus }\,{\mathrm{yr}}^{-1}$ . Although $\dot{M}$ varies by &lt;1% given constant wind and irradiation from the host, shear instabilities still emerge from wind impacts, producing ~10% fluctuations of He* transit depths over hour-long timescales. The common assumption that He* transit depth indicates the fluctuation of $\dot{M}$ is problematic. The trailing tail is more susceptible than planet adjacency to the shear instabilities; thus, the line profile is more variable in the blueshifted wing, while the transit light curve is more variable after midtransit. We stress that the synergy between Lyα (higher altitudes, lower density) and He* (lower altitudes, higher density) transit observations, particularly simultaneous ones, yields better understanding of planetary outflows and stellar wind properties.

Keywords: Hydrodynamical simulations, Hydrodynamics, Astronomical simulations, Astrochemistry, Exoplanet astronomy, Exoplanet evolution, Exoplanet atmospheres
Two Populations of Carbon-enhanced Metal-poor Stars in the Disk System of the Milky Way. We present a chemodynamical analysis of low-resolution (R ~ 1300) spectroscopy of ~50,000 stars from the AAOmega Evolution of Galactic Structure survey, focusing on two key populations of (in total) 650 carbon-enhanced metal-poor (CEMP) stars within the disk system of the Milky Way: a mildly prograde population (Lz &lt; 1000 kpc km s-1) and a strongly prograde population (Lz &gt; 1000 kpc km s-1). Based on their chemical and kinematic characteristics, and on comparisons with similar populations found in the recent literature, we tentatively associate the former with an ex situ inner-halo population originating from either the Gaia Sausage or Gaia-Enceladus. The latter population is linked to the metal-weak thick disk. We discuss their implications in the context of the formation history of the Milky Way.

Keywords: Milky Way formation, Stellar kinematics, Milky Way disk, Milky Way evolution, CEMP stars
Electron-scale Magnetic Peaks Upstream of the Terrestrial Bow Shock Observed by the Magnetospheric Multiscale Mission. The solar wind has rich wave activity and various magnetic structures. Here we report on a new type of magnetic structure in the solar wind using the unprecedented high temporal resolution data from the Magnetospheric Multiscale Mission. We find that a train of magnetic peaks with a size less than 1 ion inertial length exists upstream of the terrestrial bow shock. The electron number density and the perpendicular electron temperature have a slight decrease inside the magnetic peaks, leading to a decrease of the electron thermal pressure in the structure. These structures are pressure-balanced, and they are approximately stationary in the ambient electron flow. These electron-scale magnetic peaks are identified as magnetic bottle-like, and their cross sections are roughly circular. The electron velocity has a bipolar feature relative to the ambient flow in the cross section, indicating the existence of an electron vortex. The current density is mainly contributed by electrons. The peaks occur in a marginally mirror-stable environment; thus they are not locally generated by mirror instabilities. We suggest that the origin of the electron vortex might help to shed light on the formation of electron-scale magnetic peaks in the solar wind.

Keywords: Solar wind, Planetary bow shocks
Rapid Formation of Jupiter and Wide-orbit Exoplanets in Disks with Pressure Bumps. The formation of gas-giant planets within the lifetime of a protoplanetary disk is challenging especially far from a star. A promising model for the rapid formation of giant-planet cores is pebble accretion in which gas drag during encounters leads to high accretion rates. Most models of pebble accretion consider disks with a monotonic, radial pressure profile. This causes a continuous inward flux of pebbles and inefficient growth. Here we examine planet formation in a disk with multiple, intrinsic pressure bumps. In the outer disk, pebbles become trapped near these bumps allowing rapid growth under suitable conditions. In the inner disk, pebble traps may not exist because the inward gas advection velocity is too high. Pebbles here are rapidly removed. In the outer disk, growth is very sensitive to the initial planet mass and the strength of turbulence. This is because turbulent density fluctuations raise planetary eccentricities, increasing the planet-pebble relative velocity. Planetary seeds above a distance-dependent critical mass grow to a Jupiter mass in 0.5-3 Myr out to at least 60 au in a 0.03 solar-mass disk. Smaller bodies remain near their initial mass, leading to a sharp dichotomy in growth outcomes. For turbulent α = 1e-4, the critical masses are 1e-4M⊕ and 1e-3M⊕ at 9 and 75 au, respectively. Pressure bumps in disks may explain the large mass difference between the giant planets and Kuiper Belt objects, and also the existence of wide-orbit planets in some systems.

Keywords: Exoplanet migration, Solar system gas giant planets, Planetary system formation, Protoplanetary disks, Planetesimals, Exoplanet formation, Planet formation
Quantitative Age Estimation of Supernova Remnants and Associated Pulsars. The age of a supernova remnant (SNR) is, though undoubtedly one of the most important properties for study of its evolution, difficult to estimate reliably in most cases. In this study, we compare the dynamical and plasma ages of the SNRs and characteristic ages of their associated pulsars with the corresponding SNRs' ages that are generally thought to be reliable (tr): historical and light-echo ages of the SNRs, kinematic ages of the ejecta knots and kinematic ages of the associated neutron stars (NS). The kinematic age of ejecta knots or an NS is the time that they have taken to reach the current positions from the explosion center. We use all of the available 24 systems for which tr is already available (historical, light-echo, and ejecta kinematic ages) or measurable (NS kinematic age). We estimate the NS kinematic ages for eight SNR-NS systems by determining quantitatively the geometric centers of the SNR shells. The obtained tr ranges from 33 yr to ≈400 kyr. We find that the two SNR ages, dynamical and plasma ages, are consistent with tr within a factor of four, whereas the characteristic ages of the pulsars differ from tr by more than a factor of four in some systems. Using the tr summarized in this work, we present the initial spin periods of the associated pulsars, which are more strictly constrained than the previous works, as well.

Keywords: Neutron stars, X-ray astronomy, Pulsars, Supernova remnants, Radio continuum emission
Spectral Observations of Superthin Galaxies. We conduct spectral observations of 138 superthin galaxies (STGs) with high radial-to-vertical stellar disk scale ratios with the Dual Imaging Spectrograph on the 3.5 m telescope at the Apache Point Observatory (APO) to obtain the ionized gas rotation curves with R ~5000 resolution. We also performed near-infrared (NIR) H and Ks photometry for 18 galaxies with the NICFPS camera on the 3.5 m telescope. The spectra, the NIR photometry, and published optical and NIR photometry are used for modeling that utilizes the thickness of the stellar disk and rotation curves simultaneously. The projection and dust extinction effects are taken into account. We evaluate eight models that differ in their free parameters and constraints. As a result, we estimated the masses and scale lengths of the galactic dark halos. We find systematic differences between the properties of our red and blue STGs. The blue STGs have a large fraction of dynamically underevolved galaxies whose vertical velocity dispersion is low in both gas and stellar disks. The dark halo-to-disk scale ratio is shorter in the red STGs than in the blue ones, but in a majority of all STGs, this ratio is under 2. The optical color (r - i) of the STGs correlates with their rotation curve maximum, vertical velocity dispersion in stellar disks, and mass of the dark halo. We conclude that there is a threshold central surface density of 50 M⊙ pc-2 below which we do not observe very thin, rotationally supported galactic disks.

Keywords: Galaxy dark matter halos, Disk galaxies, Galactic and extragalactic astronomy
Stellar Evolution in the Disks of Active Galactic Nuclei Produces Rapidly Rotating Massive Stars. Stars can either be formed in or captured by the accretion disks in active galactic nuclei (AGNs). These AGN stars are irradiated and subject to extreme levels of accretion, which can turn even low-mass stars into very massive ones (M &gt; 100M⊙) whose evolution may result in the formation of massive compact objects (M &gt; 10M⊙). Here we explore the spins of these AGN stars and the remnants they leave behind. We find that AGN stars rapidly spin up via accretion, eventually reaching near-critical rotation rates. They further maintain near-critical rotation even as they shed their envelopes, become compact, and undergo late stages of burning. This makes them good candidates to produce high-spin massive black holes, such as the ones seen by LIGO-Virgo in GW 190521g, as well as long gamma-ray bursts and the associated chemical pollution of the AGN disk.

Keywords: Massive stars, Stellar physics, Stellar evolutionary models, Quasars
Probing the Sea of Cosmic Rays by Measuring Gamma-Ray Emission from Passive Giant Molecular Clouds with HAWC. The study of high-energy gamma rays from passive giant molecular clouds (GMCs) in our Galaxy is an indirect way to characterize and probe the paradigm of the "sea" of cosmic rays in distant parts of the Galaxy. By using data from the High Altitude Water Cerenkov (HAWC) Observatory, we measure the gamma-ray flux above 1 TeV of a set of these clouds to test the paradigm. We selected high galactic latitude clouds that are in HAWC's field of view and that are within 1 kpc distance from the Sun. We find no significant excess emission in the cloud regions, nor when we perform a stacked log-likelihood analysis of GMCs. Using a Bayesian approach, we calculate 95% credible interval upper limits of the gamma-ray flux and estimate limits on the cosmic-ray energy density of these regions. These are the first limits to constrain gamma-ray emission in the multi-TeV energy range (&gt;1 TeV) using passive high galactic latitude GMCs. Assuming that the main gamma-ray production mechanism is due to proton-proton interaction, the upper limits are consistent with a cosmic-ray flux and energy density similar to that measured at Earth.

Keywords: Galactic cosmic rays, Gamma-rays, High energy astrophysics
High-energy Emission from Tidal Disruption Events in Active Galactic Nuclei. Tidal disruption events (TDEs) taking place in active galactic nuclei (AGNs) are different from ordinary TDEs. In these events, the returning tidal debris stream drills through the preexisting AGN accretion disk near the stream pericenter, destroying the inner disk in the process, and then intersects with the disk a second time at radii ranging from a few times to hundreds of times the pericenter distance. The debris dynamics of such TDEs, and hence their appearance, are distinct from those of ordinary TDEs. Here we explore the observational signatures of this "second impact" of the stream with the disk. Strong shocks form as the dilute stream is stopped by the denser disk. Compton cooling of the shocked material produces hard X-rays and even soft γ-rays, with most of the energy emitted between ~10 keV and 1 MeV. The luminosity follows the mass-return rate, peaking between ~1042 and 1044 erg s-1. The X-ray hardness and the smoothness of the light curve provide possible means for distinguishing the second impact from ordinary AGN flares, which exhibit softer spectra and more irregular light curves.

Keywords: Accretion, Black hole physics, Hydrodynamical simulations, High energy astrophysics, Gravitation, Tidal disruption, X-ray transient sources, Active galactic nuclei, Gamma-ray transient sources