Sazuna/UAT_keywords huggingface dataset:
Cooling-induced Vortex Decay in Keplerian Disks. Vortices are readily produced by hydrodynamical instabilities, such as the Rossby wave instability, in protoplanetary disks. However, large-scale asymmetries indicative of dust-trapping vortices are uncommon in submillimeter continuum observations. One possible explanation is that vortices have short lifetimes. In this paper, we explore how radiative cooling can lead to vortex decay. Elliptical vortices in Keplerian disks go through adiabatic heating and cooling cycles. Radiative cooling modifies these cycles and generates baroclinicity that changes the potential vorticity of the vortex. We show that the net effect is typically a spin down, or decay, of the vortex for a subadiabatic radial stratification. We perform a series of two-dimensional shearing box simulations, varying the gas cooling (or relaxation) time, tcool, and initial vortex strength. We measure the vortex decay half-life, thalf, and find that it can be roughly predicted by the timescale ratio tcool/tturn, where tturn is the vortex turnaround time. Decay is slow in both the isothermal (tcool ≪ tturn) and adiabatic (tcool ≫ tturn) limits; it is fastest when tcool ~ 0.1 tturn, where thalf is as short as ~300 orbits. At tens of astronomical units where disk rings are typically found, tturn is likely much longer than tcool, potentially placing vortices in the fast decay regime.

Keywords: Hydrodynamical simulations, Planetary-disk interactions, Protoplanetary disks, Circumstellar disks, Planet formation
Nuclear Physics Multimessenger Astrophysics Constraints on the Neutron Star Equation of State: Adding NICER's PSR J0740+6620 Measurement. In the past few years, new observations of neutron stars (NSs) and NS mergers have provided a wealth of data that allow one to constrain the equation of state (EOS) of nuclear matter at densities above nuclear saturation density. However, most observations were based on NSs with masses of about 1.4 M☉, probing densities up to ~three to four times the nuclear saturation density. Even higher densities are probed inside massive NSs such as PSR J0740+6620. Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620, and X-ray observations by the NICER and XMM telescopes constrained its radius. Based on these new measurements, we revisit our previous nuclear physics multimessenger astrophysics constraints and derive updated constraints on the EOS describing the NS interior. By combining astrophysical observations of two radio pulsars, two NICER measurements, the two gravitational-wave detections GW170817 and GW190425, detailed modeling of the kilonova AT 2017gfo, and the gamma-ray burst GRB 170817A, we are able to estimate the radius of a typical 1.4 M☉ NS to be ${11.94}_{-0.87}^{+0.76}\,\mathrm{km}$ at 90% confidence. Our analysis allows us to revisit the upper bound on the maximum mass of NSs and disfavors the presence of a strong first-order phase transition from nuclear matter to exotic forms of matter, such as quark matter, inside NSs.

Keywords: Neutron stars, Neutron star cores, Gravitational waves, Nuclear physics
Constraining Type Ia Supernova Delay Time with Spatially Resolved Star Formation Histories. We present the delay time distribution (DTD) estimates of Type Ia supernovae (SNe Ia) using spatially resolved SN Ia host galaxy spectra from MUSE and MaNGA. By employing a grouping algorithm based on k-means and earth mover's distances (EMDs), we separated the host galaxy stellar population age distributions (SPADs) into spatially distinct regions and used maximum likelihood method to constrain the DTD of SN Ia progenitors. When a power-law model of the form DTD(t) ∝ ts(t &gt; τ) is used, we find an SN rate decay slope $s=-{1.41}_{-0.33}^{+0.32}$ and a delay time $\tau ={120}_{-83}^{+142}\mathrm{Myr}$ . Moreover, we tested other DTD models, such as a broken power-law model and a two-component power-law model, and found no statistically significant support for these alternative models.

Keywords: Type Ia supernovae
Rapid Formation of Gas-giant Planets via Collisional Coagulation from Dust Grains to Planetary Cores. Gas-giant planets, such as Jupiter, Saturn, and massive exoplanets, were formed via the gas accretion onto the solid cores, each with a mass of roughly 10 Earth masses. However, rapid radial migration due to disk-planet interaction prevents the formation of such massive cores via planetesimal accretion. Comparably rapid core growth via pebble accretion requires very massive protoplanetary disks because most pebbles fall into the central star. Although planetesimal formation, planetary migration, and gas-giant core formation have been studied with a lot of effort, the full evolution path from dust to planets is still uncertain. Here we report the result of full simulations for collisional evolution from dust to planets in a whole disk. Dust growth with realistic porosity allows the formation of icy planetesimals in the inner disk (≲10 au), while pebbles formed in the outer disk drift to the inner disk and there grow to planetesimals. The growth of those pebbles to planetesimals suppresses their radial drift and supplies small planetesimals sustainably in the vicinity of cores. This enables rapid formation of sufficiently massive planetary cores within 0.2-0.4 million years, prior to the planetary migration. Our models shows the first gas giants form at 2-7 au in rather common protoplanetary disks, in agreement with the exoplanet and solar systems.

Keywords: Planetary system formation, Solar system formation, Protoplanetary disks, Planet formation
A VLA Survey of Late-time Radio Emission from Superluminous Supernovae and the Host Galaxies. We present the results of 3 GHz radio continuum observations of 23 superluminous supernovae (SLSNe) and their host galaxies by using the Karl G. Jansky Very Large Array conducted 5-21 yr after the explosions. The sample consists of 15 Type I and 8 Type II SLSNe at z &lt; 0.3, providing one of the largest samples of SLSNe with late-time radio data. We detected radio emission from one SLSN (PTF10hgi) and five hosts with a significance of &gt;5σ. No time variability is found in late-time radio light curves of the radio-detected sources in a timescale of years except for PTF10hgi, whose variability is reported in a separate study. Comparison of star formation rates (SFRs) derived from the 3 GHz flux densities with those derived from SED modeling based on UV-NIR data shows that four hosts have an excess of radio SFRs, suggesting obscured star formation. Upper limits for undetected hosts and stacked results show that the majority of the SLSN hosts do not have a significant obscured star formation. By using the 3 GHz upper limits, we constrain the parameters for afterglows arising from interaction between initially off-axis jets and circumstellar medium (CSM). We found that the models with higher energies (Eiso ≳ several × 1053 erg) and CSM densities (n ≳ 0.01 cm-3) are excluded, but lower energies or CSM densities are not excluded with the current data. We also constrained the models of pulsar wind nebulae powered by a newly born magnetar for a subsample of SLSNe with model predictions in the literature.

Keywords: Very Large Array, Extragalactic radio sources, Circumstellar matter, Radio continuum emission, Radio astronomy, Supernovae, Radio transient sources
Mixed Modes and Asteroseismic Surface Effects. II. Subgiant Systematics. Models of solar-like oscillators yield acoustic modes at different frequencies than would be seen in actual stars possessing identical interior structure, due to modeling error near the surface. This asteroseismic "surface term" must be corrected when mode frequencies are used to infer stellar structure. Subgiants exhibit oscillations of mixed acoustic (p-mode) and gravity (g-mode) character, which defy description by the traditional p-mode asymptotic relation. Since nonparametric diagnostics of the surface term rely on this description, they cannot be applied to subgiants directly. In Paper I, we generalized such nonparametric methods to mixed modes, and showed that traditional surface-term corrections only account for mixed-mode coupling to, at best, first order in a perturbative expansion. Here, we apply those results, modeling subgiants using asteroseismic data. We demonstrate that, for grid-based inference of subgiant properties using individual mode frequencies, neglecting higher-order effects of mode coupling in the surface term results in significant systematic differences in the inferred stellar masses, and measurable systematics in other fundamental properties. While these systematics are smaller than those resulting from other choices of model construction, they persist for both parametric and nonparametric formulations of the surface term. This suggests that mode coupling should be fully accounted for when correcting for the surface term in seismic modeling with mixed modes, irrespective of the choice of correction used. The inferred properties of subgiants, in particular masses and ages, also depend on the choice of surface-term correction, in a different manner from those of both main-sequence and red giant stars.

Keywords: Stellar oscillations, Computational methods, Asteroseismology, Subgiant stars
Probing the Time Variation of a Fine Structure Constant Using Galaxy Clusters and the Quintessence Model. We explore a possible time variation of the fine structure constant (α ≅ e2/ℏc) using the Sunyaev-Zel'dovich effect measurements of galaxy clusters along with their X-ray observations. Specifically, the ratio of the integrated Comptonization parameter ${Y}_{\mathrm{SZ}}{D}_{A}^{2}$ and its X-ray counterpart YX is used as an observable to constrain the bounds on the variation of α. Considering the violation of the cosmic distance duality relation, this ratio depends on the fine structure constant of ~ α3. We use the quintessence model to provide the origin of α time variation. In order to give a robust test on α variation, two galaxy cluster samples, the 61 clusters provided by the Planck collaboration and the 58 clusters detected by the South Pole Telescope (SPT), are collected for analysis. Their X-ray observations are given by the XMM-Newton survey. Our results give $\zeta =-{0.203}_{-0.099}^{+0.101}$ for the Planck sample and $\zeta =-{0.043}_{-0.148}^{+0.165}$ for the SPT sample, indicating that α is constant with redshift within 3σ and 1σ for the two samples, respectively.

Keywords: Quintessence, Cosmological models, Galaxy clusters
Optical and Near-infrared Pulsation Properties of RR Lyrae and Population II Cepheid Variables in the Messier 15 Globular Cluster. Messier 15 (NGC 7078) is an old and metal-poor post core-collapse globular cluster that hosts a rich population of variable stars. We report new optical (gi) and near-infrared (NIR, JKs) multi-epoch observations for 129 RR Lyrae, 4 Population II Cepheids (3 BL Herculis, 1 W Virginis), and 1 anomalous Cepheid variable candidate in M15 obtained using the MegaCam and the WIRCam instruments on the 3.6 m Canada-France-Hawaii Telescope. Multi-band data are used to improve the periods and classification of variable stars, and determine accurate mean magnitudes and pulsational amplitudes from the light curves fitted with optical and NIR templates. We derive optical and NIR period-luminosity relations for RR Lyrae stars which are best constrained in the Ks band, ${m}_{{K}_{s}}=-2.333\,(0.054)\mathrm{log}P+13.948\,(0.015)$ with a scatter of only 0.037 mag. Theoretical and empirical calibrations of RR Lyrae period-luminosity-metallicity relations are used to derive a true distance modulus to M15: 15.196 ± 0.026 (statistical) ± 0.039 (systematic) mag. Our precise distance moduli based on RR Lyrae stars and Population II Cepheid variables are mutually consistent and agree with recent distance measurements in the literature based on Gaia parallaxes and other independent methods.

Keywords: Globular star clusters, Distance indicators, RR Lyrae variable stars, Stellar pulsations
Circumstellar Medium Constraints on the Environment of Two Nearby Type Ia Supernovae: SN 2017cbv and SN 2020nlb. We present deep Chandra X-ray observations of two nearby Type Ia supernovae, SN 2017cbv and SN 2020nlb, which reveal no X-ray emission down to a luminosity LX ≲ 5.3 × 1037 and ≲ 5.4 × 1037 erg s-1 (0.3-10 keV), respectively, at ~16-18 days after the explosion. With these limits, we constrain the pre-explosion mass-loss rate of the progenitor system to be $\dot{M}$ &lt; 7.2 × 10-9 and &lt; 9.7 × 10-9 M⊙ yr-1 for each (at a wind velocity vw = 100 km s-1 and a radius of R ≈ 1016 cm), assuming any X-ray emission would originate from inverse Compton emission from optical photons upscattered by the supernova shock. If the supernova environment was a constant-density medium, we would find a number density limit of nCSM &lt; 36 and &lt; 65 cm-3, respectively. These X-ray limits rule out all plausible symbiotic progenitor systems, as well as large swathes of parameter space associated with the single degenerate scenario, such as mass loss at the outer Lagrange point and accretion winds. We also present late-time optical spectroscopy of SN 2020nlb, and set strong limits on any swept up hydrogen (LHα &lt; 2.7 × 1037 erg s-1) and helium (LHe,λ6678 &lt; 2.7 × 1037 erg s-1) from a nondegenerate companion, corresponding to MH ≲ 0.7-2 × 10-3 M⊙ and MHe ≲ 4 × 10-3 M⊙. Radio observations of SN 2020nlb at 14.6 days after explosion also yield a non-detection, ruling out most plausible symbiotic progenitor systems. While we have doubled the sample of normal Type Ia supernovae with deep X-ray limits, more observations are needed to sample the full range of luminosities and subtypes of these explosions, and set statistical constraints on their circumbinary environments.

Keywords: Circumstellar matter, Type Ia supernovae
Late Afterglow Bump/Plateau around the Jet Break: Signature of a Free-to-shocked Wind Environment in Gamma-Ray Burst. A number of gamma-ray bursts (GRBs) exhibit the simultaneous bumps in their optical and X-ray afterglows around the jet break. These bumps are similar to the afterglows of GRB 170817A, except preceded by a long shallow decay. Its origin is unclear. We suggest that these late simultaneous bumps may sound a transition of circumburst environment from a free-wind medium to a constant density medium, e.g., the shocked-wind medium. In this paper, we study the emission of an external-forward shock propagating in a free-to-shocked wind environment at different viewing angles. The late simultaneous bumps/plateaux followed by a steep decay are found in the optical and X-ray afterglows for high-viewing-angle observers. In addition, these theoretical bumps are preceded by a long plateau or shallow decay, which is formed during the external-forward shock propagating in the free-wind environment. For low-viewing-angle observers, the above bumps also appear but only in the situation where the structured jet has a low characteristic angle and the deceleration radius of the in-core jet flow is at around or beyond the free-wind boundary. We search GRBs for afterglows with the late simultaneous optical and X-ray bumps followed by a steep decay. GRBs 120326A, 100901A, 100814A, and 120404A are obtained. We find that an off-core (in-core) observed external-forward shock in a free-to-shocked wind environment can well explain the optical and X-ray afterglows in GRBs 120326A, 100901A, and 100814A (GRB 120404A).

Keywords: Gamma-ray bursts, Interstellar medium wind, Interstellar medium
Halo-model Analysis of the Clustering of Photometric Luminous Red Galaxies at 0.10 ≤ z ≤1.05 from the Subaru Hyper Suprime-Cam Survey. We present the clustering analysis of photometric luminous red galaxies (LRGs) at a redshift range of 0.1 ≤ z ≤ 1.05 using 615,317 photometric LRGs selected from the Hyper Suprime-Cam Subaru Strategic Program, covering ~124 deg2. Our sample covers a broad range of stellar masses and photometric redshifts and enables a halo occupation distribution analysis to study the redshift and stellar-mass dependence of dark halo properties of LRGs. We find a tight correlation between the characteristic dark halo mass to host central LRGs, ${M}_{\min }$ , and the number density of LRGs, independently of redshifts, indicating that the formation of LRGs is associated with the global environment. The ${M}_{\min }$ of LRGs depends only weakly on the stellar mass M⋆ at M⋆ ≲ 1010.75h-2M⊙ at 0.3 &lt; z &lt; 1.05, in contrast to the case for all photometrically selected galaxies, for which ${M}_{\min }$ shows significant dependence on M⋆ even at low M⋆. The weak stellar-mass dependence is indicative of the dark halo mass being the key parameter for the formation of LRGs, rather than the stellar mass. Our result suggests that the halo mass of ~1012.5±0.2h-1M⊙ is the critical mass for an efficient halo quenching due to the halo environment. We compare our result with the result of the hydrodynamical simulation to find that low-mass LRGs at z ~ 1 will increase their stellar masses by an order of magnitude from z = 1 to 0 through mergers and satellite accretions, and that a large fraction of massive LRGs at z &lt; 0.9 consist of LRGs that recently migrated from massive green valley galaxies or those that evolved from less massive LRGs through mergers and satellite accretions.

Keywords: Galaxy dark matter halos, Galaxy formation, Large-scale structure of the universe, Observational cosmology, Clustering, Galaxy evolution
Detached Shell Carbon Stars: Tracing Thermal Pulses on the Asymptotic Giant Branch. We consider whether the subset of carbon-rich asymptotic giant branch (AGB) stars that exhibit detached, expanding circumstellar shells may reveal the past histories of these stars as having undergone helium shell flashes (thermal pulses) on the AGB. We exploit newly available Gaia parallaxes and photometry, along with archival infrared photometry, to obtain refined estimates of the luminosities of all (12) known detached shell carbon stars. We examine the relationship between these luminosities and the estimated dynamical ages (ejection times) of the detached shells associated with the 12 stars, which range from ~1000 to ~30,000 yr. When arranged according to detached shell dynamical age, the (implied) luminosity evolution of the known detached shell carbon stars closely follows the predicted "light curves" of individual thermal pulses obtained from models of AGB stars. The comparison between data and models suggests that detached shell carbon stars are descended from ~2.5 to 4.0 M⊙ progenitors. We conclude that detached shell carbon stars may serve as effective tracers of the luminosity evolution of AGB thermal pulses.

Keywords: Carbon stars, Late stellar evolution, Stellar mass loss
Galactic Extinction: How Many Novae Does It Hide and How Does It Affect the Galactic Nova Rate?. There is a long-standing discrepancy between the observed Galactic classical nova rate of ~10 yr-1 and the predicted rate from Galactic models of ~30-50 yr-1. One explanation for this discrepancy is that many novae are hidden by interstellar extinction, but the degree to which dust can obscure novae is poorly constrained. We use newly available all-sky three-dimensional dust maps to compare the brightness and spatial distribution of known novae to that predicted from relatively simple models in which novae trace Galactic stellar mass. We find that only half (53%) of the novae are expected to be easily detectable (g ≲ 15) with current all-sky optical surveys such as the All-Sky Automated Survey for Supernovae (ASAS-SN). This fraction is much lower than previously estimated, showing that dust does substantially affect nova detection in the optical. By comparing complementary survey results from the ASAS-SN, OGLE-IV, and Palomar Gattini IR surveys using our modeling, we find a tentative Galactic nova rate of ~30 yr-1, though this could be as high as ~40 yr-1, depending on the assumed distribution of novae within the Galaxy. These preliminary estimates will be improved in future work through more sophisticated modeling of nova detection in ASAS-SN and other surveys.

Keywords: White dwarf stars, Cataclysmic variable stars, Novae, Classical novae
Impact of Water-latent Heat on the Thermal Structure of Ultra-cool Objects: Brown Dwarfs and Free-floating Planets. Brown dwarfs are essential targets for understanding planetary and sub-stellar atmospheres across a wide range of thermal and chemical conditions. As surveys continue to probe ever deeper and as observing capabilities continue to improve, the number of known Y dwarfs-the coldest class of sub-stellar objects, with effective temperatures below about 600 K-is rapidly growing. Critically, this class of ultra-cool objects has atmospheric conditions that overlap with solar-system worlds and, as a result, tools and ideas developed from studying Earth, Jupiter, Saturn, and other nearby worlds are well suited for application to sub-stellar atmospheres. To that end, we developed a one-dimensional (vertical) atmospheric structure model for ultra-cool objects that includes moist adiabatic convection, as this is an important process for many solar-system planets. Application of this model across a range of effective temperatures (350, 300, 250, 200 K), metallicities ([M/H] of 0.0, 0.5, 0.7, 1.5), and gravities (log g of 4.0, 4.5, 4.7, 5.0) demonstrates strong impact of water-latent heat release on simulated temperature-pressure profiles. At the highest metallicities, water-vapor mixing ratios reach an Earth-like 3% with associated major alterations to the thermal structure in the atmospheric regions where water condenses. Spectroscopic and photometric signatures of metallicity and moist convection should be readily detectable at near- and mid-infrared wavelengths, especially with James Webb Space Telescope observations, and can help indicate the formation history of an object.

Keywords: Brown dwarfs, Planetary atmospheres, Y dwarfs, Exoplanet structure, Exoplanet atmospheres
The IGRINS YSO Survey II: Veiling Spectra of Pre-main-sequence Stars in Taurus-Auriga. We present measurements of the H- and K-band veiling for 141 young stellar objects (YSOs) in the Taurus-Auriga star-forming region using high-resolution spectra from the Immersion Grating Near-Infrared Spectrometer. In addition to providing measurements of rH and rK, we produce low-resolution spectra of the excess emission across the H and K bands. We fit temperatures to the excess spectra of 46 members of our sample and measure near-infrared excess temperatures ranging from 1200-2200 K, with an average of 1575 ± 225 K. We compare the luminosity of the excess continuum emission in Class II and Class III YSOs and find that a number of Class III sources display a significant amount of excess flux in the near-infrared. We conclude that the mid-infrared SED slope, and therefore young stellar object classification, is a poor predictor of the amount of near-infrared veiling. If the veiling arises in thermal emission from dust, its presence implies a significant amount of remaining inner-disk (&lt;1 au) material in these Class III sources. We also discuss the possibility that the veiling effects could result from massive photospheric spots, unresolved binary companions, or accretion emission. Six low-mass members of our sample contain a prominent feature in their H-band excess spectra that is consistent with veiling from cool photospheric spots.

Keywords: High resolution spectroscopy, Young stellar objects, Protoplanetary disks, Near infrared astronomy