Sazuna/UAT_keywords huggingface dataset:
A Distant Fast Radio Burst Associated with Its Host Galaxy by the Very Large Array. We present the discovery and subarcsecond localization of a new fast radio burst (FRB) by the Karl G. Jansky Very Large Array (VLA) and realfast search system. The FRB was discovered on 2019 June 14 with a dispersion measure of 959 $\mathrm{pc}\,{\mathrm{cm}}^{-3}$. This is the highest DM of any localized FRB and its measured burst fluence of 0.6 Jy ms is less than nearly all other FRBs. The source is not detected to repeat in 15 hr of VLA observing and 153 hr of CHIME/FRB observing. We describe a suite of statistical and data quality tests we used to verify the significance of the event and its localization precision. Follow-up optical/infrared photometry with Keck and Gemini associate the FRB with a pair of galaxies with $r\sim 23$ mag. The false-alarm rate for radio transients of this significance that are associated with a host galaxy is roughly $3\times {10}^{-4}\,{\mathrm{hr}}^{-1}$. The two putative host galaxies have similar photometric redshifts of ${z}_{\mathrm{phot}}\sim 0.6$, but different colors and stellar masses. Comparing the host distance to that implied by the dispersion measure suggests a modest ($\sim 50\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$) electron column density associated with the FRB environment or host galaxy/galaxies.

Keywords: Extragalactic astronomy, Radio bursts, Radio interferometry, Radio transient sources
Multiwavelength Photometry and Progenitor Analysis of the Nova V906 Car. We present optical and infrared photometry of the classical nova V906 Car, also known as Nova Car 2018 and ASASSN-18fv, which was discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) on 2018 March 16.32 UT (MJD 58193.0). The nova reached its maximum on MJD 58222.56 at Vmax = 5.84 ± 0.09 mag, and had decline times of ${t}_{2,V}=26.2$ days and ${t}_{3,V}=33.0$ days. The data from Evryscope shows that the nova had already brightened to $g^{\prime} \simeq 13$ mag five days before discovery, as compared with its quiescent magnitude of g = 20.13 ± 0.03. The extinction toward the nova, as derived from high-resolution spectroscopy, shows an estimate consistent with foreground extinction to the Carina Nebula of ${A}_{V}={1.11}_{-0.39}^{+0.54}$. The light curve resembles a rare C (cusp) class nova with a steep decline slope of α = -3.94 post-cusp flare. From the light-curve decline rate, we estimate the mass of the white dwarf to be MWD = &lt;0.8M☉, consistent with ${M}_{\mathrm{WD}}={0.71}_{-0.19}^{+0.23}$ derived from modeling the accretion disk of the system in quiescence. The donor star is likely a K-M dwarf of 0.23-0.43 ${M}_{\odot }$, which is heated by its companion.

Keywords: Extinction, Photometry, Classical novae
Softening of the Metagalactic Ionizing Background from Internal He II Absorption in Quasars. Quasars and other active galactic nuclei (AGN) are significant contributors to the metagalactic ionizing background at redshifts z &lt; 3. Recent Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) composite spectra of AGN find a harder flux distribution in the Lyman continuum, ${F}_{\nu }\propto {\nu }^{-{\alpha }_{s}}$ (αs = 1.41 ± 0.15), compared to previous studies. This index appears to be inconsistent with observed He II/H I absorption ratios (η) in the Lyα forest. We explore the effects of internal AGN absorption in the He II (4 ryd) continuum using an analytic source-function model of the ionizing background in which the emissivity (jν) arises from quasars, reprocessed by the opacity (κν) of the intervening Lyα forest and distinct AGN escape fractions ${f}_{\mathrm{esc}}^{({\rm{H}}\,{\rm{\small{I}}})}$ and ${f}_{\mathrm{esc}}^{(\mathrm{He}\,{\rm{\small{II}}})}$ at 1 ryd and 4 ryd, respectively. We also examine H I and He II photoelectric heating from the reprocessed background, whose spectral index (αb &gt; αs) depends on αs, the H I column density slope β, and the ratio $R={f}_{\mathrm{esc}}^{({\rm{H}}\,{\rm{\small{I}}})}/{f}_{\mathrm{esc}}^{(\mathrm{He}\,{\rm{\small{II}}})}$. We compare the model to Lyα absorption lines of He II and H I toward the quasar HE 2347-4342. Internal AGN absorption with ${f}_{\mathrm{esc}}^{(\mathrm{He}\,{\rm{\small{II}}})}\approx 0.6\mbox{--}0.8$ but ${f}_{\mathrm{esc}}^{({\rm{H}}\,{\rm{\small{I}}})}\approx 1$ would increase the index by Δαb ≈ 0.3-1.0, corresponding to η = 60-200 for β ≈ 1.5-1.6, in agreement with HST/COS observations at z ≈ 2.5-2.9. The observed range of ratios, η &lt; 200, constrains αb &lt; 3.4 and ${f}_{\mathrm{esc}}^{(\mathrm{He}\,{\rm{\small{II}}})}\gt 0.4$. Individual AGN with softer spectra, αs &gt; 1.7, and more internal He II absorption could produce a few absorbers with η &gt; 300, in proximity to AGN transverse to the sight line.

Keywords: Radio quiet quasars, Intergalactic medium
On the Minimum Radius of Very Massive Neutron Stars. Prospects of establishing the radii of massive neutron stars in PSR J1614 - 2230 and PSR J0740 + 6620 from Neutron Star Interior Composition ExploreR and Chandra observatories hold the potential to constrain the equation of state (EoS) of matter to densities well beyond those encountered in canonical stars of mass $\sim 1.4\,{M}_{\odot }$. In this work, we investigate the relation between the radii of very massive neutron stars up to the maximum mass, ${M}_{\max }$, supported by dense matter EoSs. Results from models with hadronic matter are contrasted with those that include a first-order hadron-to-quark phase transition. We find that a lower bound on ${M}_{\max }$ with an upper bound on the radius of massive pulsars serves to rule out quark matter that is too soft, and an upper bound on ${M}_{\max }$ with a lower bound on the radius of massive pulsars strongly disfavors a transition into quark matter that is too stiff appearing at low densities. The complementary role played by radius inferences from future gravitational-wave events of inspiraling binary neutron stars is also briefly discussed.

Keywords: Neutron stars, Stellar interiors
Local Starburst Conditions and Formation of GRB 980425/SN 1998bw within a Collisional Ring. We present the first spatially resolved study of molecular gas in the vicinity of a gamma-ray burst (GRB), using CO(2-1) emission-line observations with the Atacama Large Millimetre Array at ∼50 pc scales. The host galaxy of GRB 980425 contains a ring of high column density H I gas, which is likely to have formed due to a collision between the GRB host and its companion galaxy, within which the GRB is located. We detect 11 molecular gas clumps in the galaxy, 7 of which are within the gas ring. The clump closest to the GRB position is at a projected separation of ∼280 pc. Although it is plausible that the GRB progenitor was ejected from clusters formed in this clump, we argue that the in situ formation of the GRB progenitor is the most likely scenario. We measure the molecular gas masses of the clumps and find them to be sufficient for forming massive star clusters. The molecular gas depletion times of the clumps show a variation of ∼2 dex, comparable with the large variation in depletion times found in starburst galaxies in the nearby universe. This demonstrates the presence of starburst modes of star formation on local scales in the galaxy, even while the galaxy as a whole cannot be categorized as a starburst based on its global properties. Our findings suggest that the progenitor of GRB 9802425 was originated in a young massive star cluster formed in the starburst mode of star formation.

Keywords: Starburst galaxies, Gamma-ray bursts, Galaxy collisions, Star forming regions, Galaxy dynamics, Young massive clusters, Molecular clouds, Massive stars, Interstellar medium, Interacting galaxies, Supernovae
The Advanced Spectral Library (ASTRAL): Abundance Analysis of the Chemically Peculiar Star HR 465. This paper presents the results of the spectrum analysis of the B-type magnetic chemically peculiar star HR 465. HR 465 shows unusual abundance patterns that vary with a period of 21.5 yr. Our observations are recorded at φ = 0.45, 0.68, and 0.85 of the spectroscopic period, where φ = 0 represents the phase of maximum flux in the photometric y-band. Synthetic spectra, computed using an LTE atmosphere model, are fit to high-resolution ultraviolet Hubble Space Telescope (φ = 0.45) spectra obtained as part of the Advanced Spectral Library Project: Hot Stars program. The ultraviolet data are supplemented by high-resolution optical spectra (φ = 0.68 and 0.85) recorded at the Nordic Optical Telescope with the SOFIN spectrograph. The optical data are used as a complement to the high line-density ultraviolet spectrum to derive accurate abundances for elements without spectral lines in the ultraviolet and to improve the abundance phase coverage for many atoms/ions. This analysis presents abundance results for more than 70 atoms/ions and confirms parts of the abundance characteristics previously reported where elements with high mass numbers show significant abundance enhancements compared with solar values while some of the lighter elements show abundance deficiencies. In addition, our measured abundances are consistent with the periodic variability for chromium and rare-earth elements. Our results are compared with earlier investigations of this peculiar object to constrain stellar abundance and diffusion. * Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Keywords: High resolution spectroscopy, Bp stars, Astronomy data modeling, Stellar abundances, Chemically peculiar stars
Star-forming Sites IC 446 and IC 447: An Outcome of End-dominated Collapse of Monoceros R1 Filament. We present an analysis of multiwavelength observations of Monoceros R1 (Mon R1) complex (at d ∼760 pc). An elongated filament (length ∼14 pc, mass ∼1465 M⊙) is investigated in the complex, which is the most prominent structure in the Herschel column density map. An analysis of the FUGIN 12CO(1-0) and 13CO(1-0) line data confirms the existence of the filament traced in a velocity range of [-5, +1] km s-1. The filament is found to host two previously known sites IC 446 and IC 447 at its opposite ends. A massive young stellar object (YSO) is embedded in IC 446, while IC 447 contains several massive B-type stars. The Herschel temperature map reveals the extended warm dust emission (at Td ∼ 15-21 K) toward both the ends of the filament. The Spitzer ratio map of 4.5 μm/3.6 μm emission suggests the presence of photodissociation regions and signature of outflow activity toward IC 446 and IC 447. Based on the photometric analysis of point-like sources, clusters of YSOs are traced mainly toward the filament ends. The filament is found to be thermally supercritical showing its tendency of fragmentation, which is further confirmed by the detection of a periodic oscillatory pattern (having a period of ∼3-4 pc) in the velocity profile of 13CO. Our outcomes suggest that the fragments distributed toward the filament ends have rapidly collapsed, and had formed the known star-forming sites. Overall, the elongated filament in Mon R1 is a promising sample of the "end-dominated collapse" scenario, as discussed by Pon et al. (2011, 2012).

Keywords: Star formation, Pre-main sequence stars, H II regions, Interstellar medium
Exploring the Lower Mass Gap and Unequal Mass Regime in Compact Binary Evolution. On 2019 August 14, the LIGO and Virgo detectors observed GW190814, a gravitational-wave signal originating from the merger of a $\simeq \,23\,{M}_{\odot }$ black hole (BH) with a $\simeq \,2.6\,{M}_{\odot }$ compact object. GW190814's compact-binary source is atypical both in its highly asymmetric masses and in its lower-mass component lying between the heaviest known neutron star (NS) and lightest known BH in a compact-object binary. If formed through isolated binary evolution, the mass of the secondary is indicative of its mass at birth. We examine the formation of such systems through isolated binary evolution across a suite of assumptions encapsulating many physical uncertainties in massive-star binary evolution. We update how mass loss is implemented for the neutronization process during the collapse of the proto-compact object to eliminate artificial gaps in the mass spectrum at the transition between NSs and BHs. We find it challenging for population modeling to match the empirical rate of GW190814-like systems while simultaneously being consistent with the rates of other compact binary populations inferred from gravitational-wave observations. Nonetheless, the formation of GW190814-like systems at any measurable rate requires a supernova engine model that acts on longer timescales such that the proto-compact object can undergo substantial accretion immediately prior to explosion, hinting that if GW190814 is the result of massive-star binary evolution, the mass gap between NSs and BHs may be narrower or nonexistent.

Keywords: Neutron stars, Core-collapse supernovae, Stellar evolutionary models, Stellar mass black holes, Gravitational wave sources, Gravitational waves, Supernovae, Astrophysical black holes
On the Relation between Diffuse Bands and Other Interstellar Features. We discuss possible relations between different constituents of interstellar clouds, such as gas atoms (Fe I), simple molecular species (CH, CN), and the carriers of the puzzling diffuse interstellar bands (DIBs 5780, 5797, 5850 Å) as well as dust grains. We exemplify that abundances of carriers of these spectral features, revealed by the Doppler components, may be astonishingly poorly related to each other. Spectra of interstellar clouds seem to be sensitive to the changes of the environmental parameters such as density, temperature, and irradiation from nearby stars. The diffuse bands' carriers likely do not occupy the same volumes with CH, CN, or Fe I and/or are much less sensitive to the processes related to the formation/destruction of these species. * This Letter includes data gathered with the UT2 telescope—a part of the VLT ESO telescope (Chile).

Keywords: Interstellar dust, Interstellar medium, Interstellar clouds, Interstellar atomic gas
An Interstellar Synthesis of Glycerol Phosphates. Glycerol phosphates define key molecules pertaining to the Origin of Life question and represent the essential stereo-dictating unit of phospholipids that may self-assemble in aqueous media into prebiotic cell membranes. However, the prebiotic formation pathways to glycerol phosphate have remained elusive to date. In this Letter, we expose a facile pathway toward the abiotic synthesis of glycerol phosphate isomers in phosphine (PH3) doped interstellar analog ices of methanol (CH3OH), carbon dioxide (CO2), or water (H2O) upon exposure to energetic electrons as a proxy of secondary electrons generated by the penetration of Galactic cosmic rays into interstellar ices at 10 K. The synthetic routes proposed here overcome obstacles of terrestrial-based scenarios that are inhibited by the low solubility of phosphates in water and the unfavorable nature of phosphorylation reactions in aqueous solution, thus revealing a potential pathway to prebiotic glycerol phosphates.

Keywords: Laboratory astrophysics, Astrochemistry, Astrobiology, Interstellar medium, Pre-biotic astrochemistry
Effects of Cowling Resistivity in the Weakly Ionized Chromosphere. The physics of the solar chromosphere is complex from both theoretical and modeling perspectives. The plasma temperature from the photosphere to the corona increases from ∼5000 K to ∼1 million K over a distance of only ∼10,000 km from the chromosphere and the transition region. Certain regions of the solar atmosphere have sufficiently low temperature and ionization rates to be considered as weakly ionized. In particular, this is true at the lower chromosphere. As a result, the Cowling resistivity is orders of magnitude greater than the Coulomb resistivity. Ohm's law therefore includes anisotropic dissipation. To evaluate the Cowling resistivity, we need to know the external magnetic field strength and to estimate the neutral fraction as a function of the bulk plasma density and temperature. In this study, we determine the magnetic field topology using the non-force-free field extrapolation technique based on Solar Dynamics Observatory/Helioseismic and Magnetic Imager SHARP vector magnetogram data, and the stratified density and temperature profiles from the Maltby-M umbral core model for sunspots. We investigate the variation and effects of Cowling resistivity on heating and magnetic reconnection in the chromosphere as the flare-producing active region (AR) 11166 evolves. In particular, we analyze a C2.0 flare emerging from AR 11166 and find a normalized reconnection rate of 0.051.

Keywords: Solar active region magnetic fields, Magnetohydrodynamics, Solar magnetic reconnection, Solar active regions, Solar chromospheric heating, Solar chromosphere
First Detection of the GI-type of Intrinsic Alignments of Galaxies Using the Self-calibration Method in a Photometric Galaxy Survey. Weak gravitational lensing is one of the most promising cosmological probes to constrain dark matter, dark energy, and the nature of gravity at cosmic scales. Intrinsic alignments (IAs) of galaxies have been recognized as one of the most serious systematic effects facing gravitational lensing. Such alignments must be isolated and removed to obtain a pure lensing signal. Furthermore, the alignments are related to the processes of galaxy formation, so their extracted signal can help in understanding such formation processes and improving their theoretical modeling. We report in this Letter the first detection of the gravitational shear-intrinsic shape (GI) correlation and the intrinsic shape-galaxy density (Ig) correlation using the self-calibration method in a photometric redshift survey. These direct measurements are made from the KiDS-450 photometric galaxy survey with a significance of 3.65σ in the third bin for the Ig correlation, and 3.51σ for the GI cross-correlation between the third and fourth bins. The self-calibration method uses the information available from photometric surveys without needing to specify an IA model and will play an important role in validating IA models and IA mitigation in future surveys such as the Rubin Observatory Legacy Survey of Space and Time, Euclid, and WFIRST.

Keywords: Weak gravitational lensing, Observational cosmology
A Comparative Study of Host Galaxy Properties between Fast Radio Bursts and Stellar Transients. Recent arcsecond localizations of fast radio bursts and identifications of their host galaxies confirmed their extragalactic origin. While FRB 121102 resides in the bright region of a dwarf star-forming galaxy, other FRBs reside in more massive galaxies and are related to older stellar populations. We compare the host galaxy properties of nine FRBs with those of several types of stellar transients: from young to old populations, long-duration gamma-ray bursts (LGRBs), superluminous supernovae (SLSNe), SNe Ibc, SNe II, SNe Ia, and short-duration gamma-ray bursts (SGRBs). We find that the stellar mass and star formation rate of the FRB host galaxies, taken as a whole sample, prefer a medium to old population, and are against a young population, similar to LGRBs and SLSNe by a null probability of 0.02. Individually, the host of FRB 121102 is consistent with that of young population objects; the environment of FRB 180924 is similar to that of SGRBs; and the environment of FRB 190523 is similar to those of SNe Ia. These results are consistent with the magnetar engine model for FRBs, if magnetars produced from extreme explosions (GRBs/SLSNe) and those from regular channels (e.g., those producing Galactic magnetars) can both produce FRBs.

Keywords: Radio transient sources
Constraining Cosmic-Ray Acceleration in the Magnetospheric Gaps of Sgr A*. Sagittarius A* (Sgr A*) is a potential very high energy (VHE) γ-ray and cosmic-ray source. We examine limits to gap-type particle acceleration in the magnetosphere of Sgr A*, showing that in the current phase of activity proton acceleration to PeV energies is possible, with injection powers into the environment usually limited to several 1036 erg s-1. Compton upscattering of ambient soft photons by gap-accelerated electrons could yield TeV emission compatible with the detected VHE point source. We explore the dependency of the results on changes in the accretion rate showing that higher stages in the past are unlikely to increase the power output unless the inner accretion flows itself changed its configuration.

Keywords: Galactic cosmic rays, Black hole physics, Galactic center, High energy astrophysics
Does Matter Matter? Using the Mass Distribution to Distinguish Neutron Stars and Black Holes. Gravitational-wave detectors have opened a new window through which we can observe black holes (BHs) and neutron stars (NSs). Analyzing the 11 detections from LIGO/Virgo's first gravitational-wave catalog, GWTC-1, we investigate whether the power-law fit to the BH mass spectrum can also accommodate the binary neutron star (BNS) event GW170817, or whether we require an additional feature, such as a mass gap in between the NS and BH populations. We find that with respect to the power-law fit to binary black hole (BBH) masses, GW170817 is an outlier at the 0.13% level, suggesting a distinction between NS and BH masses. A single power-law fit across the entire mass range is in mild tension with (a) the detection of one source in the BNS mass range (∼1-2.5 M⊙), (b) the absence of detections in the "mass-gap" range (∼2.5-5 M⊙), and (c) the detection of 10 sources in the BBH mass range (≳5 M⊙). Instead, the data favor models with a feature between NS and BH masses, including a mass gap (Bayes factor of 4.6) and a break in the power law, with a steeper slope at NS masses compared to BH masses (91% credibility). We estimate the merger rates of compact binaries based on our fit to the global mass distribution, finding ${{R}}_{{\rm{B}}{\rm{N}}{\rm{S}}}={871}_{-805}^{+3015}$ and ${{ \mathcal R }}_{\mathrm{BBH}}={47.5}_{-28.8}^{+57.9}\ {\mathrm{Gpc}}^{-3}\ {\mathrm{yr}}^{-1}$ . We conclude that, even in the absence of any prior knowledge of the difference between NSs and BHs, the gravitational-wave data alone already suggest two distinct populations of compact objects.

Keywords: Neutron stars, Stellar mass black holes, Astrostatistics, Gravitational wave astronomy, Gravitational waves, Compact objects, Astrophysical black holes
The Role of Active Galactic Nuclei in the Quenching of Massive Galaxies in the SQuIGG ěc{L} E Survey. We study the incidence of nuclear activity in a large sample of massive post-starburst (PSB) galaxies at $z\sim 0.7$ selected from the Sloan Digital Sky Survey, and identify active galactic nuclei based on radio continuum and optical emission lines. Over our mass range of ${10}^{10.6}\mbox{--}{10}^{11.5}$ ${M}_{\odot }$ , the incidence of radio activity is weakly dependent on stellar mass and independent of stellar age, while radio luminosity depends strongly on stellar mass. Optical nuclear activity incidence depends most strongly on the Dn4000 line index, a proxy for stellar age, with an active fraction that is ∼10 times higher in the youngest versus oldest PSB galaxies. Since a similar trend is seen between age and molecular gas fractions, we argue that, like in local galaxies, the age trend reflects a peak in available fueling rather than feedback from the central black hole on the surrounding galaxy.

Keywords: AGN host galaxies, Radio galaxies, Quenched galaxies