Sazuna/UAT_keywords huggingface dataset:
The Massive and Distant Clusters of WISE Survey. VII. The Environments and Properties of Radio Galaxies in Clusters at z ∼ 1. We present the results from a study with NSF’s Karl G. Jansky Very Large Array (VLA) to determine the radio morphologies of extended radio sources and the properties of their host galaxies in 50 massive galaxy clusters at z ∼ 1. We find a majority of the radio morphologies to be Fanaroff-Riley type IIs. By analyzing the infrared counterparts of the radio sources, we find that ∼40% of the host galaxies are the candidate brightest cluster galaxy and ∼83% are consistent with being one of the top six most massive galaxies in the cluster. We investigate the role of environmental factors on the radio-loud AGN population by examining correlations between environmental and radio-galaxy properties. We find that the highest stellar mass hosts (M * ≳ 4 × 1011 M ⊙) are confined to the cluster center and host compact jets. There is evidence for an increase in the size of the jets with cluster-centric radius, which may be attributed to the decreased ICM pressure confinement with increasing radius. Besides this correlation, there are no other significant correlations between the properties of the radio-AGN (luminosity, morphology, or size) and environmental properties (cluster richness and location within the cluster). The fact that there are more AGN in the cluster environment than the field at this epoch, combined with the lack of strong correlation between galaxy and environmental properties, argues that the cluster environment fosters radio activity but does not solely drive the evolution of these sources at this redshift.

Keywords: Galaxy clusters, AGN host galaxies, High-redshift galaxy clusters, Radio lobes, Rich galaxy clusters, Radio galaxies, Active galactic nuclei, Galaxy evolution, Fanaroff-Riley radio galaxies, Infrared galaxies, Radio continuum emission, Radio interferometry
Exploring the Origin of Moving Groups and Diagonal Ridges by Simulations of Stellar Orbits and Birthplaces. The present paper is the culmination of a series aimed at contributing to the understanding of the kinematic structures of the solar neighborhood (SN), explaining the origin of the Local Arm, and relating the moving groups with the spiral-arms resonances in the disk. With a model for the Galactic potential, with the Sun inside the spiral corotation resonance (CR), we integrate the 2D orbits of test particles distributed in birthplaces along the main spiral arms, the Local Arm, and in the axisymmetric disk. A comparison of the resulting U-V plane of the SN with that provided by Gaia DR2 confirms our previous conclusion that the moving groups of Coma Berenices, Pleiades, and Hyades are associated with the CR, and that the Hercules stream is formed by the bulk of high-order inner Lindblad resonances. The kinematic structures result from stellar orbits trapped by the spiral resonances in a timespan of ∼1 Gyr, indicating the long-lived nature of the spiral structure and challenging recent arguments in favor of short-lived structures originated from incomplete phase mixing in the Galactic disk. As a byproduct, our simulations give some insight into the birthplaces of the stars presently located in the SN; the majority of stars of the main moving groups and the Hercules stream were likely born in the Local Arm, while stars of the Sirius group possibly originated from the outer segment of the Sagittarius-Carina arm. We also propose the spiral resonances as the dynamical origin for the diagonal ridges in the Galactic distribution of rotation velocities.

Keywords: Stellar kinematics, Milky Way dynamics, Solar neighborhood, Spiral arms, Milky Way disk, Milky Way evolution
Impact of the Rotation and Compactness of Progenitors on the Mass of Black Holes. We investigate the impact of stellar rotation on the formation of black holes (BHs) by means of our population synthesis code SEVN. Rotation affects the mass function of BHs in several ways. In massive metal-poor stars, fast rotation reduces the minimum zero-age main sequence (ZAMS) mass for a star to undergo pair instability and pulsational pair instability. Moreover, stellar winds are enhanced by rotation, peeling off the entire hydrogen envelope. As a consequence of these two effects, the maximum BH mass we expect from the collapse of a rotating metal-poor star is only ∼45 M ⊙, while the maximum mass of a BH born from a nonrotating star is ∼60 M ⊙. Furthermore, stellar rotation reduces the minimum ZAMS mass for a star to collapse into a BH from ∼18-25 M ⊙ to ∼13-18 M ⊙. Finally, we have investigated the impact of different core-collapse supernova (CCSN) prescriptions on our results. While the threshold value of compactness for direct collapse and the fallback efficiency strongly affect the minimum ZAMS mass for a star to collapse into a BH, the fraction of the hydrogen envelope that can be accreted onto the final BH is the most important ingredient in determining the maximum BH mass. Our results confirm that the interplay between stellar rotation, CCSNe and pair instability plays a major role in shaping the BH mass spectrum.

Keywords: Massive stars, Stellar mass black holes, Stellar mass loss, Gravitational wave astronomy, Computational methods, Astrophysical black holes
The Colors and Sizes of Recently Quenched Galaxies: A Result of Compact Starburst before Quenching. We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 Å) at z ∼ 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, span a wide range of colors, and we find a clear correlation between color and half-light radius, such that bluer galaxies are smaller. We build simple toy models to explain this correlation: a normal star-forming disk plus a central, compact starburst component. Bursts with exponential decay timescale of ∼100 Myr that produce ∼10% to more than 100% of the preexisting masses can reproduce the observed correlation. More significant bursts also produce bluer and smaller descendants. Our findings imply that when galaxies shut down star formation rapidly, they generally had experienced compact, starburst events and that the large, observed spread in sizes and colors mostly reflects a variety of burst strengths. Recently quenched galaxies should have younger stellar ages in the centers; multiwavelength data with high spatial resolution are required to reveal the age gradient. Highly dissipative processes should be responsible for this type of formation history. While determining the mechanisms for individual galaxies is challenging, some recently quenched galaxies show signs of gravitational interactions, suggesting that mergers are likely an important mechanism in triggering the rapid shutdown of star formation activities at z ∼ 0.8.

Keywords: Galaxy formation, Galaxy colors, Galaxy structure, Galaxy stellar content, Galaxy mergers, Galaxy evolution, Galaxy quenching
A Catalog of AGN Host Galaxies Observed with HST/ACS: Correlations between Star Formation and AGN Activity. We present the Advanced Camera for Surveys Active Galactic Nuclei (ACS-AGN) Catalog, a catalog of 2585 active galactic nucleus (AGN) host galaxies that are at redshifts 0.2 &lt; z &lt; 2.5 and that were imaged with the Hubble Space Telescope’s Advanced Camera for Surveys (ACS). Using the ACS General Catalog (ACS-GC) as our initial sample, we select an AGN subsample using Spitzer and Chandra data along with their respective established AGN selection criteria. We then gather further multiwavelength photometric data in order to construct spectral energy distributions (SEDs). Using these SEDs, we are able to derive multiple AGN and host galaxy properties, such as star formation rate (SFR), AGN luminosity, stellar mass, and nuclear column density. From these data, we show that AGN host galaxies tend to lie below the star-forming main sequence, with X-ray-selected AGN host galaxies being more offset than IR-selected AGN host galaxies. This suggests that there is some process, possibly negative feedback, in AGN host galaxies causing decreased star formation. We also demonstrate that there is a positive trend between the SFR and AGN luminosity in AGN host galaxies, in individual redshift bins, and across all redshift bins, and that both are correlated with the stellar mass of their galaxies. This points toward an underlying link between the stellar mass, stellar growth, and supermassive black hole growth in a galaxy.

Keywords: AGN host galaxies, Active galactic nuclei, Galaxy evolution, Star formation, Galaxy quenching
A Catalog of Emission-line Galaxies from the Faint Infrared Grism Survey: Studying Environmental Influence on Star Formation. We present a catalog of 208 0.3 &lt; z &lt; 2.1 emission-line galaxies (ELGs) selected from 1D slitless spectroscopy obtained using Hubble’s WFC3 G102 grism, as part of the Faint Infrared Grism Survey. We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission-line fluxes and errors, redshifts, and equivalent widths for Hα λ6563, [O III] λλ4959, 5007, and [O II] λ3727 emission lines, for ELGs down to AB(F105W) &gt;28 and &gt;10-17 erg cm-2 s-1 line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy’s environment. We use seventh-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [O III] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SFR) versus stellar mass and find no significant influence of environment on that relation. We calculate SFRs and find no dependence of SFR on local galaxy surface density for 0.3 &lt; z &lt; 0.8 Hα emitters and for 0.8 &lt; z &lt; 1.3 [O III] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities Σ ≤ 30 Mpc-2, we find no consistent effect of environment on star formation.

Keywords: Galaxy evolution, Emission line galaxies, Galaxy environments
Explosive Nucleosynthesis in Sub-Chandrasekhar-mass White Dwarf Models for Type Ia Supernovae: Dependence on Model Parameters. Recent observations of Type Ia supernovae (SNe Ia) have shown diversified properties of the explosion strength, light curves, and chemical composition. To investigate possible origins of such diversities in SNe Ia, we have presented multidimensional hydrodynamical studies of explosions and associated nucleosynthesis in near-Chandrasekhar-mass carbon-oxygen (CO) white dwarfs (WDs) for a wide range of parameters. In the present paper, we extend our wide parameter survey of models to the explosions of sub-Chandrasekhar-mass CO WDs. We take the double-detonation model for the explosion mechanism. The model parameters of the survey include a metallicity of Z = 0-5 Z ⊙, a CO WD mass of M = 0.90-1.20 M ⊙, and a He envelope mass of M He = 0.05-0.20 M ⊙. We also study how the initial He detonation configuration, such as spherical, bubble, and ring shapes, triggers the C detonation. For these parameters, we derive the minimum He envelope mass necessary to trigger the C detonation. We then examine how the explosion dynamics and associated nucleosynthesis depend on these parameters, and we compare our results with the previous representative models. We compare our nucleosynthesis yields with the unusual abundance patterns of Fe-peak elements and isotopes observed in SNe Ia SN 2011fe, SN 2012cg, and SN 2014J, as well as SN Ia remnant 3C 397, to provide constraints on their progenitors and environments. We provide the nucleosynthesis yields table of the sub-Chandrasekhar-mass explosions, to discuss their roles in the galactic chemical evolution and archaeology.

Keywords: Hydrodynamical simulations, Type Ia supernovae, Explosive nucleosynthesis, Chemical abundances
Two New Rapidly Rotating ON Stars Found with LAMOST. The ON stars are a rare subtype of O stars of uncertain origin. We report two new, rapidly rotating ON stars found in data acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. LS I +61 28 is an ON8.5 Vn dwarf with a projected equatorial rotational velocity of {V}{{e}}\sin I≃ 298 {km} {{{s}}}-1, while HDE 236672 is an ON9 IVn subgiant with {V}{{e}}\sin I≃ 253 {km} {{{s}}}-1. The former is the first rapidly rotating ON dwarf to be found, and the latter is only the third ON subgiant. The luminosity classes of non-supergiant ON stars appear to be influenced by the axial inclination angle I: the rapidly rotating giants are close to equator-on, while ON dwarfs with lower {V}{{e}}\sin I values are viewed more nearly pole-on. Combining parallaxes and proper motions from Gaia Data Release 2 with radial-velocity measurements, we investigate the kinematics of non-supergiant ON stars and infer that the dynamics, rapid rotation, and surface nitrogen characteristics may all be consequences of binary interaction.

Keywords: Stellar rotation, O stars
HST/COS Spectra of the Wind Lines of VFTS 102 and 285. Rapid rotation in massive stars imposes a latitudinal variation in the mass loss from radiatively driven winds that can lead to enhanced mass loss at the poles (with little angular momentum loss) and/or equator (with maximal angular momentum loss). Here we present an examination of the stellar wind lines of the two O-type stars with the fastest known equatorial velocities, VFTS 102 (V\sin I=610+/- 30 km s-1 O9: Vnnne+) and VFTS 285 (V\sin I=609+/- 29 km s-1 O7.5 Vnnn) in the Large Magellanic Cloud. Ultraviolet spectra of both stars were obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. The spectrum of VFTS 285 displays a fast outflow in N V and a much slower wind in Si IV, and we argue that there is a two-wind regime in which mass loss is strong at the poles (fast and tenuous wind) but dominant at the equator (slow and dense winds). These ions and wind lines are not present in the spectrum of the cooler star VFTS 102, but the double-peaked Hα emission in its spectrum implies equatorial mass loss into a circumstellar disk. The results suggest that in the fastest rotating O-stars, most mass is lost as an equatorial outflow, promoting angular momentum loss that contributes to a spin-down over time.

Keywords: Stellar rotation, Stellar winds, Massive stars, Large Magellanic Cloud
Photometric Redshift Estimation with Galaxy Morphology Using Self-organizing Maps. We use multiband optical and near-infrared photometric observations of galaxies in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey to predict photometric redshifts using artificial neural networks. The multiband observations span from 0.39 to 8.0 μm for a sample of ∼1000 galaxies in the GOODS-S field for which robust size measurements are available from Hubble Space Telescope Wide Field Camera 3 observations. We use self-organizing maps (SOMs) to map the multidimensional photometric and galaxy size observations while taking advantage of existing spectroscopic redshifts at 0 &lt; z &lt; 2 for independent training and testing sets. We show that use of photometric and morphological data led to redshift estimates comparable to redshift measurements from modeling of spectral energy distributions and from SOMs without morphological measurements.

Keywords: Multi-color photometry, Galaxy properties, Redshifted, Galaxies, Galaxy radii
Ghostly Strong Lyα Absorbers: Tracers of Gas Flows in the Close Vicinity of Quasars?. We have searched the Sloan Digital Sky Survey Data Release 12 for ghostly strong Lyα (DLA) systems. These systems, located at the redshift of the quasars, show strong absorption from low-ionization atomic species but reveal no H I Lyα absorption. Our search has, for the first time, resulted in a sample of 30 homogeneously selected ghostly absorbers with z QSO &gt; 2.0. Thirteen of the ghostly absorbers exhibit absorption from other H I Lyman series lines. The lack of Lyα absorption in these absorbers is consistent with them being dense and compact with projected sizes smaller than the broad-line region of the background quasar. Although uncertain, the estimated median H I column density of these absorbers is logN(H I) ∼ 21.0. We compare the properties of ghostly absorbers with those of eclipsing DLAs that are high-column-density absorbers, located within 1500 km s-1 of the quasar emission redshift and showing strong Lyα emission in their DLA trough. We discover an apparent sequence in the observed properties of these DLAs, with ghostly absorbers showing wider H I kinematics, stronger absorptions from high-ionization species, C II and Si II excited states, and a higher level of dust extinction. Since we estimate that all these absorbers have similar metallicities, logZ/{Z}⊙ ∼ -1.0, we conclude that ghostly absorbers are part of the same population as eclipsing DLAs, except that they are denser and located closer to the central active galactic nuclei.

Keywords: Galactic winds, Quasar absorption line spectroscopy, Quasars, Interstellar line absorption, Galaxy structure, Circumgalactic medium, Interstellar dust extinction, Interstellar absorption, Active galactic nuclei, Intergalactic medium, Extragalactic astronomy
Two-dimensional Inflow-Outflow Solution of Supercritical Accretion Flow. We present the two-dimensional inflow-outflow solutions of radiation hydrodynamic equations of supercritical accretion flows. Compared with prior studies, we include all components of the viscous stress tensor. We assume steady-state flow and use self-similar solutions in the radial direction to solve the equations in the r-θ domain of spherical coordinates. The set of differential equations have been integrated from the rotation axis to the equatorial plane. We find that the self-similarity assumption requires that the radial profile of density is described by ρ(r) ∝ r -0.5. Correspondingly, the radial profile of the mass inflow rate decreases with decreasing radius as {\dot{M}}in}\propto r. An inflow-outflow structure has been found in our solution. Inflow exists in the region θ &gt; 65°, while above that the flow moves outward and outflow could launch. The driving forces of the outflow are analyzed and it is found that the radiation force is dominant and pushes the gas particles outward with poloidal velocity ∼0.25c. The properties of the outflow are also studied. The results show that the mass flux-weighted angular momentum of the inflow is lower than that of the outflow, thus the angular momentum of the flow can be transported by the outflow. We also analyze the convective stability of the supercritical disk and find that in the absence of a magnetic field, the flow is convectively unstable. Our analytical results are fully consistent with the previous numerical simulations of supercritical accretion flow.

Keywords: Black hole physics, Black holes, High energy astrophysics, Seyfert galaxies, Active galactic nuclei
Hot Super-Earths with Hydrogen Atmospheres: A Model Explaining Their Paradoxical Existence. In this paper, we propose a new mechanism that could explain the survival of hydrogen atmospheres on some hot super-Earths. We argue that on close-orbiting tidally locked super-Earths, the tidal forces, together with the orbital and rotational centrifugal forces, can partially confine the atmosphere on the nightside. Assuming a super-terran body with an atmosphere dominated by volcanic species and a large hydrogen component, the heavier molecules can be shown to be confined within latitudes of ≲80° while the volatile hydrogen is not. Because of this disparity, the hydrogen has to slowly diffuse out into the dayside where X-ray and ultraviolet irradiation destroys it. For this mechanism to take effect, it is necessary for the exoplanet to become tidally locked before losing the totality of its hydrogen envelope. Consequently, for super-Earths with this proposed configuration, it is possible to solve the tidal-locking and mass-loss timescales in order to constrain their formation "birth" masses. Our model predicts that 55 Cancri e formed with a day length between approximately 17-18.5 hr and an initial mass less than ∼12M⊕, hence allowing it to become tidally locked before the complete destruction of its atmosphere. For comparison, CoRoT-7b, an exoplanet with very similar properties to 55 Cancri e but lacking an atmosphere, formed with a day length significantly different from ∼20.5 hr while also having an initial mass smaller than ∼9M⊕.

Keywords: Solar ultraviolet emission, Near ultraviolet astronomy, Atmospheric circulation, Solar extreme ultraviolet emission, Super Earths, Tidal interaction, Exoplanet atmospheres
A Variant Stellar-to-nebular Dust Attenuation Ratio on Subgalactic and Galactic Scales. The state-of-the-art geometry models of stars/dust suggest that dust attenuation toward nebular regions ( ${A}_{V,\mathrm{gas}}$ ) is always larger than that of stellar regions ( ${A}_{V,\mathrm{star}}$ ). Utilizing the newly released integral field spectroscopic data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we investigate whether and how the ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ ratio varies from subgalactic to galactic scales. On a subgalactic scale, we report a stronger correlation between ${A}_{V,\mathrm{star}}$ and ${A}_{V,\mathrm{gas}}$ for more active H II regions. The local ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ is found to have moderate nonlinear correlations with three tracers of diffuse ionized gas (DIG), as well as indicators of gas-phase metallicity and ionization. The DIG regions tend to have larger ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ compared to classic H II regions excited by young OB stars. Metal-poor regions with a higher ionized level suffer much less nebular attenuation and thus have larger ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ ratios. A low- ${A}_{V,\mathrm{gas}}$ and high- ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ sequence, which can be resolved into DIG-dominated and metal-poor regions, on the three BPT diagrams is found. Based on these observations, we suggest that besides the geometry of stars/dust, local physical conditions such as metallicity and ionized level also play an important role in determining the ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ . On a galactic scale, the global ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ ratio has strong correlations with stellar mass (M*), moderate correlations with star formation rate (SFR) and metallicity, and weak correlations with inclination and specific SFR. Galaxies with larger M* and higher SFR that are more metal-rich tend to have smaller ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ ratios. Such correlations form a decreasing trend of ${A}_{V,\mathrm{star}}/{A}_{V,\mathrm{gas}}$ along the star-forming main sequence and mass-metallicity relation. The dust growth process accompanied by galaxy growth might be one plausible explanation for our observations.

Keywords: Interstellar dust extinction, Warm ionized medium, Galaxy evolution, Interstellar medium, H II regions