Sazuna/UAT_keywords huggingface dataset:
Volumetric Rates of Luminous Red Novae and Intermediate-luminosity Red Transients with the Zwicky Transient Facility. Luminous red novae (LRNe) are transients characterized by low luminosities and expansion velocities, and they are associated with mergers or common-envelope ejections in stellar binaries. Intermediate-luminosity red transients (ILRTs) are an observationally similar class with unknown origins, but they are generally believed to be either electron-capture supernovae in super-asymptotic giant branch stars or outbursts in dusty luminous blue variables (LBVs). In this paper, we present a systematic sample of eight LRNe and eight ILRTs detected as part of the Census of the Local Universe (CLU) experiment on the Zwicky Transient Facility (ZTF). The CLU experiment spectroscopically classifies ZTF transients associated with nearby (&lt;150 Mpc) galaxies, achieving 80% completeness for m  r  &lt; 20 mag. Using the ZTF-CLU sample, we derive the first systematic LRNe volumetric rate of ${7.8}_{-3.7}^{+6.5}\times {10}^{-5}$ Mpc-3 yr-1 in the luminosity range -16 ≤ M  r  ≤ -11 mag. We find that, in this luminosity range, the LRN rate scales as ${dN}/{dL}\propto {L}^{-2.5\pm 0.3}$ -significantly steeper than the previously derived scaling of L -1.4±0.3 for lower-luminosity LRNe (M  V  ≥ -10 mag). The steeper power law for LRNe at high luminosities is consistent with the massive merger rates predicted by binary population synthesis models. We find that the rates of the brightest LRNe (M  r  ≤ -13 mag) are consistent with a significant fraction of them being progenitors of double compact objects that merge within a Hubble time. For ILRTs, we derive a volumetric rate of ${2.6}_{-1.4}^{+1.8}\times {10}^{-6}$ Mpc-3 yr-1 for M  r  ≤ -13.5 mag, which scales as ${dN}/{dL}\propto {L}^{-2.5\pm 0.5}$ . This rate is ~1%-5% of the local core-collapse supernova rate and is consistent with theoretical ECSN rate estimates.

Keywords: Binary stars, Core-collapse supernovae, Transient sources, Luminous blue variable stars, Time domain astronomy, Common envelope evolution
SN 2018gk Revisited: the Photosphere, the Central Engine, and the Putative Dust. We perform a comprehensive study of the physical properties of SN 2018gk, which is a luminous Type IIb supernova (SN). We find that the early-time photospheric velocity varies from a larger value to a smaller one before the photosphere reaches a temperature floor. We generalize the photosphere modulus and fit the multiband light curves (LCs) of SN 2018gk. We find that the 56Ni mass model requires ~0.90 M ⊙ of 56Ni, which is larger than the derived ejecta mass (~0.10 M ⊙). Alternatively, we use the magnetar plus 56Ni and the fallback plus 56Ni models to fit the LCs of SN 2018gk, finding that the two models can fit the LCs. We favor the magnetar plus 56Ni model since the parameters are rather reasonable (M ej = 1.65 M ⊙, M Ni = 0.05 M ⊙, which is smaller than the upper limit of the 56Ni mass that can by synthesized by neutrino-powered core-collapse SNe, B = 6.52 × 1014 G, which is comparable to magnetic fields in luminous and superluminous SNe studied in the literature, and P 0 = 10.42 ms, which is comparable to initial periods for luminous SNe), while the validity of the fallback plus 56Ni model depends on the accretion efficiency (η). Therefore, we suggest that SN 2018gk might be an SN IIb powered mainly by a central engine. Finally, we confirm the near-IR excesses of the spectral energy distributions of SN 2018gk at some epochs and constrain the physical properties of the putative dust using the blackbody plus dust emission model.

Keywords: Magnetars, Type II supernovae, Circumstellar dust, Supernovae
A Reexamination of Phosphorus and Chlorine Depletions in the Diffuse Interstellar Medium. We present a comprehensive examination of interstellar P and Cl abundances based on an analysis of archival spectra acquired with the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer. Column densities of P II, Cl I, and Cl II are determined for a combined sample of 107 sight lines probing diffuse atomic and molecular gas in the local Galactic interstellar medium. We reevaluate the nearly linear relationship between the column densities of Cl I and H2, which arises from the rapid conversion of Cl+ to Cl0 in regions where H2 is abundant. Using the observed total gas-phase P and Cl abundances, we derive depletion parameters for these elements, adopting the methodology of Jenkins. We find that both P and Cl are essentially undepleted along sight lines showing the lowest overall depletions. Increasingly severe depletions of P are seen along molecule-rich sight lines. In contrast, gas-phase Cl abundances show no systematic variation with molecular hydrogen fraction. However, enhanced Cl (and P) depletion rates are found for a subset of sight lines showing elevated levels of Cl ionization. An analysis of neutral chlorine fractions yields estimates for the amount of atomic hydrogen associated with the H2-bearing gas in each direction. These results indicate that the molecular fraction in the H2-bearing gas is at least 10% for all sight lines with $\mathrm{log}N({{\rm{H}}}_{2})\gtrsim 18$ and that the gas is essentially fully molecular at $\mathrm{log}N({{\rm{H}}}_{2})\approx 21$ . * Based on observations made with the NASA/ESA Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer mission, obtained from the MAST data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Keywords: Interstellar dust, Interstellar line absorption, Interstellar abundances, Interstellar medium, Diffuse interstellar clouds
From Carbon to Cobalt: Chemical Compositions and Ages of z   0.7 Quiescent Galaxies. We present elemental abundance patterns (C, N, Mg, Si, Ca, Ti, V, Cr, Fe, Co, and Ni) for a population of 135 massive quiescent galaxies at z ~ 0.7 with ultra-deep rest-frame optical spectroscopy drawn from the LEGA-C survey. We derive average ages and elemental abundances in four bins of stellar velocity dispersion (σ  v ) ranging from 150-250 km s-1 using a full-spectrum hierarchical Bayesian model. The resulting elemental abundance measurements are precise to 0.05 dex. The majority of elements, as well as the total metallicity and stellar age, show a positive correlation with σ  v . Thus, the highest dispersion galaxies formed the earliest and are the most metal-rich. We find only mild or nonsignificant trends between [X/Fe] and σ  v , suggesting that the average star formation timescale does not strongly depend on velocity dispersion. To first order, the abundance patterns of the z ~ 0.7 quiescent galaxies are strikingly similar to those at z ~ 0. However, at the lowest-velocity dispersions, the z ~ 0.7 galaxies have slightly enhanced N, Mg, Ti, and Ni abundance ratios and earlier formation redshifts than their z ~ 0 counterparts. Thus, while the higher-mass quiescent galaxy population shows little evolution, the low-mass quiescent galaxies population has grown significantly over the past 6 Gyr. Finally, the abundance patterns of both z ~ 0 and z ~ 0.7 quiescent galaxies differ considerably from theoretical prediction based on a chemical evolution model, indicating that our understanding of the enrichment histories of these galaxies is still very limited.

Keywords: Galaxy stellar content, Galaxy abundances, Galaxy evolution, Early-type galaxies
Steeper Scattered Disks Buckle Faster. Disks of low-mass bodies scattered by giant planets to large semimajor axis and constant periapsis orbits are vulnerable to a buckling instability. This instability exponentially grows orbital inclinations, raises periapsis distances, and coherently tilts orbits resulting in clustering of arguments of periapsis. The dynamically hot system is then susceptible to the formation of a lopsided mode. Here we show that the timescale of the buckling instability decreases as the radial surface density of the population becomes more centrally dense, i.e., steeper scattered disks buckle faster. Accounting for differential apsidal precession driven by giant planets, we find that ~10 M ⊕ is sufficient for a primordial scattered disk in the trans-Neptunian region to have been unstable if ${dN}\propto {a}^{-2.5}{da}$ .

Keywords: Detached objects, Scattered disk objects, Solar system evolution, Trans-Neptunian objects
Eccentric Dust Ring in the IRS 48 Transition Disk. Crescent-shaped structures in transition disks hold the key to studying the putative companions to the central stars. The dust dynamics, especially that of different grain sizes, is important to understanding the role of pressure bumps in planet formation. In this work, we present deep dust continuum observation with high resolution toward the Oph IRS 48 system. For the first time, we are able to significantly trace and detect emission along 95% of the ring crossing the crescent-shaped structure. The ring is highly eccentric with an eccentricity of 0.27. The flux density contrast between the peak of the flux and its counterpart along the ring is ~270. In addition, we detect a compact emission toward the central star. If the emission is an inner circumstellar disk inside the cavity, it has a radius of at most a couple of astronomical units with a dust mass of 1.5 × 10-8 M ☉, or 0.005 M ⊕. We also discuss the implications of the potential eccentric orbit on the proper motion of the crescent, the putative secondary companion, and the asymmetry in velocity maps.

Keywords: Dust continuum emission, Protoplanetary disks, Submillimeter astronomy, Interplanetary dust, Interferometry
Searching for Gravitational-wave Counterparts Using the Transiting Exoplanet Survey Satellite. In 2017, the LIGO and Virgo gravitational-wave (GW) detectors, in conjunction with electromagnetic (EM) astronomers, observed the first GW multimessenger astrophysical event, the binary neutron star (BNS) merger GW170817. This marked the beginning of a new era in multimessenger astrophysics. To discover further GW multimessenger events, we explore the synergies between the Transiting Exoplanet Survey Satellite (TESS) and GW observations triggered by the LIGO-Virgo-KAGRA Collaboration (LVK) detector network. TESS's extremely wide field of view (~2300 deg2) means that it could overlap with large swaths of GW localizations, which often span hundreds of square degrees or more. In this work, we use a recently developed transient detection pipeline to search TESS data collected during the LVK's third observing run, O3, for any EM counterparts. We find no obvious counterparts brighter than about 17th magnitude in the TESS bandpass. Additionally, we present end-to-end simulations of BNS mergers, including their detection in GWs and simulations of light curves, to identify TESS's kilonova discovery potential for the LVK's next observing run (O4). In the most optimistic case, TESS will observe up to one GW-found BNS merger counterpart per year. However, TESS may also find up to five kilonovae that did not trigger the LVK network, emphasizing that EM-triggered GW searches may play a key role in future kilonova detections. We also discuss how TESS can help place limits on EM emission from binary black hole mergers and rapidly exclude large sky areas for poorly localized GW events.

Keywords: LIGO, Transient detection, Gravitational wave astronomy
Formation of the Transition Region for the Quiet Sun. We propose a partially ionized collisional two-fluid model of the formation of the transition region between the cool dense chromosphere and hot tenuous corona for the quiet Sun. The chromosphere is treated as an isothermal gravity-bound two-fluid stratified atmosphere without appreciable vertical flow, on average. The different scale heights of the two fluids result in vertical evolution of the ionization state, and the transition region can be defined according to the ionization fraction. The transition region starts at the altitude where the ionization fraction reaches 0.5, the demarcation between the weakly and strongly ionized gas. The upper border of the region is defined as the temperature at which the particles possess enough energy for ionization, i.e., the first ionization potential. Within the transition region is a diffusion process in which the cold chromospheric particles gain energy and ionize through random collisions with hot coronal particles diffusing upward into the corona, whereas, when colliding with cold chromospheric particles, hot coronal particles lose energy, recombine, and fall into the chromosphere. The type II spicules can be generated when and where the local heating rate is so high that the conditions for a stratified chromosphere are not satisfied; upward flow is formed, penetrating the corona where the chromospheric gas in the spicule is ionized and dispersed. The enhanced radiation via those chromospheric neutral particles cools the coronal gas, and more recombination occurs, producing enhanced downward diffusion. The model reproduces key structural features of the transition region from first principles and a minimum of arbitrary parameters.

Keywords: Solar chromosphere, Ionization, Solar transition region
A Luminous Dust-obscured Tidal Disruption Event Candidate in a Star-forming Galaxy at 42 Mpc. While the vast majority of tidal disruption events (TDEs) have been identified by wide-field sky surveys in the optical and X-ray bands, recent studies indicate that a considerable fraction of TDEs may be dust obscured and thus preferentially detected in the infrared (IR) wave bands. In this Letter, we present the discovery of a luminous mid-IR nuclear flare (termed WTP14adbjsh), identified in a systematic transient search of archival images from the NEOWISE mid-IR survey. The source reached a peak luminosity of L ≃ 1043 erg s-1 at 4.6 μm in 2015 before fading in the IR with a TDE-like F ∝ t -5/3 decline, radiating a total of more than 3 × 1051 erg in the last 7 yr. The transient event took place in the nearby galaxy NGC 7392, at a distance of around 42 Mpc; yet, no optical or X-ray flare is detected. We interpret the transient as the nearest TDE candidate detected in the last decade, which was missed at other wavelengths due to dust obscuration, hinting at the existence of TDEs that have been historically overlooked. Unlike most previously detected TDEs, the transient was discovered in a star-forming galaxy, corroborating earlier suggestions that dust obscuration suppresses significantly the detection of TDEs in these environments. Our results demonstrate that the study of IR-detected TDEs is critical in order to obtain a complete understanding of the physics of TDEs and to conclude whether TDEs occur preferentially in a particular class of galaxies.

Keywords: Tidal disruption, Astrophysical black holes, Galaxy nuclei
Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and τ Cet. During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations suggest a substantial decrease in the magnetic braking efficiency when stars reach a critical value of the Rossby number, the stellar rotation period normalized by the convective overturn timescale. Cooler stars have deeper convection zones with longer overturn times, reaching this critical Rossby number at slower rotation rates. The nature and timing of the transition to weakened magnetic braking have previously been constrained by several solar analogs and two slightly hotter stars. In this Letter, we derive the first direct constraints from stars cooler than the Sun. We present new spectropolarimetry of the old G8 dwarf τ Cet from the Large Binocular Telescope, and we reanalyze a published Zeeman Doppler image of the younger G8 star 61 UMa, yielding the large-scale magnetic field strengths and morphologies. We estimate mass-loss rates using archival X-ray observations and inferences from Lyα measurements, and we adopt other stellar properties from asteroseismology and spectral energy distribution fitting. The resulting calculations of the wind braking torque demonstrate that the rate of angular momentum loss drops by a factor of 300 between the ages of these two stars (1.4-9 Gyr), well above theoretical expectations. We summarize the available data to help constrain the value of the critical Rossby number, and we identify a new signature of the long-period detection edge in recent measurements from the Kepler mission.

Keywords: Spectropolarimetry, Stellar magnetic fields, Stellar winds, Stellar rotation, Stellar evolution
MAXI J1848-015: The First Detection of Relativistically Moving Outflows from a Globular Cluster X-Ray Binary. Over the past decade, observations of relativistic outflows from outbursting X-ray binaries in the Galactic field have grown significantly. In this work, we present the first detection of moving and decelerating radio-emitting outflows from an X-ray binary in a globular cluster. MAXI J1848-015 is a recently discovered transient X-ray binary in the direction of the globular cluster GLIMPSE-C01. Using observations from the Karl G. Jansky Very Large Array, and a monitoring campaign with the MeerKAT observatory for 500 days, we model the motion of the outflows. This represents some of the most intensive, long-term coverage of relativistically moving X-ray binary outflows to date. We use the proper motions of the outflows from MAXI J1848-015 to constrain the component of the intrinsic jet speed along the line of sight, ${\beta }_{\mathrm{int}}\cos {\theta }_{\mathrm{ejection}}$ , to be =0.19 ± 0.02. Assuming it is located in GLIMPSE-C01, at 3.4 kpc, we determine the intrinsic jet speed, β int = 0.79 ± 0.07, and the inclination angle to the line of sight, θ ejection = 76° ± 2°. This makes the outflows from MAXI J1848-015 somewhat slower than those seen from many other known X-ray binaries. We also constrain the maximum distance to MAXI J1848-015 to be 4.3 kpc. Finally, we discuss the implications of our findings for the nature of the compact object in this system, finding that a black hole primary is a viable (but as-of-yet unconfirmed) explanation for the observed properties of MAXI J1848-015. If future data and/or analysis provide more conclusive evidence that MAXI J1848-015 indeed hosts a black hole, it would be the first black hole X-ray binary in outburst identified in a Galactic globular cluster.

Keywords: Neutron stars, Globular star clusters, Radio jets, Black holes, Stellar accretion, Low-mass x-ray binary stars
JWST and ALMA Imaging of Dust-obscured, Massive Substructures in a Typical z ∼ 3 Star-forming Disk Galaxy. We present an identification of dust-attenuated star-forming galactic-disk substructures in a typical star-forming galaxy (SFG), UDF2, at z = 2.696. To date, substructures containing significant buildup of stellar mass and actively forming stars have yet to be found in typical (i.e., main-sequence) SFGs at z &gt; 2. This is due to the strong dust attenuation common in massive galaxies at the epoch and the scarcity of high-resolution, high-sensitivity extinction-independent imaging. To search for disk substructures, we subtracted the central stellar-mass disk from the JWST/NIRCam rest-frame 1.2 μm image (0.″13 resolution) and subtracted, in the visibility plane, the central starburst disk from Atacama Large Millimeter/submillimeter Array (ALMA) rest-frame 240 μm observations (0.″03 resolution). The residual images revealed substructures at rest-frame 1.2 μm colocated with those found at rest-frame 240 μm, ≃2 kpc away from the galactic center. The largest substructure contains ≃20% of the total stellar mass and ≃5% of the total star formation rate of the galaxy. While UDF2 exhibits a kinematically ordered velocity field of molecular gas consistent with a secularly evolving disk, more sensitive observations are required to characterize the nature and the origin of this substructure (spiral arms, minor merger, or other types of disk instabilities). UDF2 resides in an overdense region (N ≥ 4 massive galaxies within 70 kpc projected distance at z = 2.690-2.697) and the substructures may be associated with interaction-induced instabilities. Importantly, a statistical sample of such substructures identified with JWST and ALMA could play a key role in bridging the gap between the bulge-forming starburst and the rest of the galaxy.

Keywords: Galaxy structure, High-redshift galaxies
Compact Steep Spectrum Radio Sources with Enhanced Star Formation Are Smaller Than 10 kpc. Compact steep spectrum (CSS) radio sources are active galactic nuclei (AGN) that have radio jets propagating only on galactic scales, defined as having projected linear size (LS) of up to 20 kpc. CSS sources are generally hosted by massive early-type galaxies with little ongoing star formation; however, a small fraction are known to have enhanced star formation. Using archival data from the Faint Images of the Radio Sky at Twenty cm survey, the Very Large Array Sky Survey, and the Sloan Digital Sky Survey, we identify a volume-limited sample of 166 CSS sources at z &lt; 0.2 with L 1.4 GHz &gt; 1024 W Hz-1. Comparing the star formation rates and linear sizes of these CSS sources, we find that the ≈14% of CSS sources with specific star formation rates above 0.01 Gyr-1 all have LS &lt; 10 kpc. We discuss the possible mechanisms driving this result, concluding that it is likely the excess star formation in these sources occurred in multiple bursts and ceased prior to the AGN jet being triggered.

Keywords: AGN host galaxies, Extragalactic radio sources, Radio galaxies, Active galactic nuclei, Star formation
Flux-resolved Spectropolarimetric Evolution of the X-Ray Pulsar Hercules X-1 Using IXPE. We conduct a spectropolarimetric study of the accreting X-ray pulsar Hercules X-1 using observations with the Imaging X-ray Polarimetry Explorer (IXPE). IXPE monitored the source in three different epochs, sampling two "Main-on" and one "Short-on" state of the well-known super-orbital period of the source. We find that the 2-7 keV polarization fraction increases significantly from ~7% to 9% in the Main-on state to ~15%-19% in the Short-on state, while the polarization angle remains more or less constant or changes slightly, ~47°-59°, in all three epochs. The polarization degree and polarization angle are consistent with being energy independent for all three epochs. We propose that in the Short-on state, when the neutron star is partially blocked by the disk warp, the increase in the polarization fraction can be explained as a result of the preferential obstruction of one of the magnetic poles of the neutron star.

Keywords: X-ray astronomy, Accretion, Spectropolarimetry, High energy astrophysics, Stellar accretion disks