Sazuna/UAT_keywords huggingface dataset:
System-level Fractionation of Carbon from Disk and Planetesimal Processing. Finding and characterizing extrasolar Earth analogs will rely on interpretation of the planetary system's environmental context. The total budget and fractionation between C-H-O species sensitively affect the climatic and geodynamic state of terrestrial worlds, but their main delivery channels are poorly constrained. We connect numerical models of volatile chemistry and pebble coagulation in the circumstellar disk with the internal compositional evolution of planetesimals during the primary accretion phase. Our simulations demonstrate that disk chemistry and degassing from planetesimals operate on comparable timescales and can fractionate the relative abundances of major water and carbon carriers by orders of magnitude. As a result, individual planetary systems with significant planetesimal processing display increased correlation in the volatile budget of planetary building blocks relative to no internal heating. Planetesimal processing in a subset of systems increases the variance of volatile contents across planetary systems. Our simulations thus suggest that exoplanetary atmospheric compositions may provide constraints on when a specific planet formed.

Keywords: Extrasolar rocky planets, Exoplanet atmospheres, Pre-biotic astrochemistry, Astrobiology, Planetesimals, Planet formation
Superadiabaticity in Jupiter and Giant Planet Interiors. Interior models of giant planets traditionally assume that at a given radius (i.e., pressure) the density should be larger than or equal to the one corresponding to a homogeneous, adiabatic stratification throughout the planet (referred to as the "outer adiabat"). The observations of Jupiter's gravity field by Juno combined with the constraints on its atmospheric composition appear to be incompatible with such a profile. In this Letter, we show that the above assumption stems from an incorrect understanding of the Schwarzschild-Ledoux criterion, which is only valid on a local scale. In order to fulfill the buoyancy stability condition, the density gradient with pressure in a nonadiabatic region must indeed rise more steeply than the local adiabatic density gradient. However, the density gradient can be smaller than the one corresponding to the outer adiabat at the same pressure because of the higher temperature in an inhomogeneously stratified medium. Deep enough, the density can therefore be lower than the one corresponding to the outer adiabat. We show that this is permitted only if the slope of the local adiabat becomes shallower than the slope of the outer adiabat at the same pressure, as found in recent Jupiter models due to the increase of both specific entropy and adiabatic index with depth. We examine the dynamical stability of this structure and show that it is stable against nonadiabatic perturbations. The possibility of such an unconventional density profile in Jupiter further complicates our understanding of the internal structure and evolution of (extrasolar) giant planets.

Keywords: Exoplanet structure, Planetary interior
An Empirical Proxy for the Second Integral of Motion in Rotating Barred or Tri-axial Potentials. We identify an effective proxy for the analytically unknown second integral of motion (I2) for rotating barred or tri-axial potentials. Planar orbits of a given energy follow a tight sequence in the space of the time-averaged angular momentum and its amplitude of fluctuation. The sequence monotonically traces the main orbital families in the Poincaré map, even in the presence of resonant and chaotic orbits. This behavior allows us to define the calibrated angular momentum, the average angular momentum ( $\overline{{L}_{z}}$ ) normalized by the amplitude of its fluctuation ( ${\sigma }_{{L}_{z}}$ ), as a numerical proxy for I2. It also implies that the amplitude of fluctuation in Lz, previously underappreciated, contains valuable information. This new proxy allows one to classify orbital families easily and accurately, even for real orbits in N-body simulations of barred galaxies. It is a good diagnostic tool of dynamical systems, and may facilitate the construction of equilibrium models.

Keywords: Orbits, Galaxy dynamics, Barred spiral galaxies
Poking Holes: Looking for Gaps in LIGO/Virgo's Black Hole Population. Stellar evolution models predict the existence of a gap in the black hole mass spectrum from ∼55 M⊙-120 M⊙ due to pair-instability supernovae (PISNe). We investigate the possible existence of such an "upper" mass gap in the second gravitational-wave transient catalog (GWTC-2) by hierarchically modeling the astrophysical distribution of black hole masses. We extend the TRUNCATED and POWERLAW+PEAK mass distribution families to allow for an explicit gap in the mass distribution, and apply the extended models to GWTC-2. We find that with the TRUNCATED model there is mild evidence favoring an upper mass gap with log Bayes Factor $\mathrm{ln}{ \mathcal B }=2.79$ , inferring the lower and upper bounds at ${56.12}_{-4.38}^{+7.54}\,{M}_{\odot }$ and ${103.74}_{-6.32}^{+17.01}\,{M}_{\odot }$ respectively. When using the POWERLAW+PEAK model, we find no preference for the gap. When imposing tighter priors on the gap bounds centered on the expected PISNe gap bounds, the log Bayes factors in favor of a gap mildly increase. These results are however contingent on the parameter inference for the most massive binary, GW190521, for which follow-up analyses showed the source may be an intermediate mass ratio merger that has component masses straddling the gap. Using the GW190521 posterior samples from the analysis in Nitz &amp; Capano (2021), we find an increase in Bayes factors in favor of the gap. However, the overall conclusions are unchanged: there is no preference for a gap when using the POWERLAW+PEAK model. This work paves the way for constraining the physics of pair-instability and pulsational pair-instability supernovae and high-mass black hole formation.

Keywords: Black holes, Stellar mass black holes, Gravitational wave sources, Gravitational wave astronomy, Supernova remnants, Gravitational waves, Astrophysical black holes
Giant Metrewave Radio Telescope Detection of HI 21 cm Emission from Star-forming Galaxies at z ≈ 1.3. We report a ≈400 hr Giant Metrewave Radio Telescope (GMRT) search for HI 21 cm emission from star-forming galaxies at z = 1.18-1.39 in seven fields of the DEEP2 Galaxy Survey. Including data from an earlier 60 hr GMRT observing run, we co-added the HI 21 cm emission signals from 2841 blue star-forming galaxies that lie within the FWHM of the GMRT primary beam. This yielded a 5.0σ detection of the average HI 21 cm signal from the 2841 galaxies at an average redshift &lt;z&gt; ≈ 1.3, only the second detection of HI 21 cm emission at z ≥ 1. We obtain an average HI mass of &lt;MHI&gt; = (3.09 ± 0.61) × 1010 M⊙ and an HI-to-stellar mass ratio of 2.6 ± 0.5, both significantly higher than values in galaxies with similar stellar masses in the local universe. We also stacked the 1.4 GHz continuum emission of the galaxies to obtain a median star formation rate (SFR) of 14.5 ± 1.1 M⊙yr-1. This implies an average HI depletion timescale of ≈2 Gyr for blue star-forming galaxies at z ≈ 1.3, a factor of ≈3.5 lower than that of similar local galaxies. Our results suggest that the HI content of galaxies toward the end of the epoch of peak cosmic SFR density is insufficient to sustain their high SFR for more than ≈2 Gyr. Insufficient gas accretion to replenish the HI could then explain the observed decline in the cosmic SFR density at z &lt; 1.

Keywords: Radio spectroscopy, Galaxy evolution, Neutral hydrogen clouds
Dwarf Satellites of High-z Lyman Break Galaxies: A Free Lunch for JWST. We show that the James Webb Space Telescope (JWST) will be able to detect dwarf satellites of high-z Lyman break galaxies (LBGs). To this end, we use cosmological simulations following the evolution of a typical M⋆ ≃ 1010 M⊙ LBG up to z ≃ 6, and analyze the observational properties of its five satellite dwarf galaxies (107 M⊙ &lt; M⋆ &lt; 109 M⊙). Modeling their stellar emission and dust attenuation, we reconstruct their rest-frame ultraviolet-optical spectra for 6 &lt; z &lt; 6.5. JWST/NIRCam synthetic images show that the satellites can be spatially resolved from their host, and their emission is detectable by planned deep surveys. Moreover, we build synthetic spectral energy distributions and color-magnitude diagrams for the satellites. We conclude that the color F200W-F356W is a powerful diagnostic tool for understanding their physical properties once they have been identified. For example, F200W-F356W ≲ -0.25 can be used to identify star-bursting (SFR ∼ 5 M⊙ yr-1), low-mass (M⋆ ≲ 5 × 108 M⊙) systems, with ∼80% of their stars being young and metal poor $[\mathrm{log}({Z}_{\star }/{Z}_{\odot })\lt -0.5$ ].

Keywords: Cosmology, Dwarf galaxies, High-redshift galaxies
The McDonald Accelerating Stars Survey (MASS): Discovery of a Long-period Substellar Companion Orbiting the Old Solar Analog HD 47127. Brown dwarfs with well-determined ages, luminosities, and masses provide rare but valuable tests of low-temperature atmospheric and evolutionary models. We present the discovery and dynamical mass measurement of a substellar companion to HD 47127, an old (≈7-10 Gyr) G5 main-sequence star with a mass similar to the Sun. Radial velocities of the host star with the Harlan J. Smith Telescope uncovered a low-amplitude acceleration of 1.93 ± 0.08 m s-1 yr-1 based on 20 years of monitoring. We subsequently recovered a faint (ΔH = 13.14 ± 0.15 mag) comoving companion at 1"95 (52 au) with follow-up Keck/NIRC2 adaptive optics imaging. The radial acceleration of HD 47127 together with its tangential acceleration from Hipparcos and Gaia EDR3 astrometry provide a direct measurement of the three-dimensional acceleration vector of the host star, enabling a dynamical mass constraint for HD 47127 B (67.5-177 MJup at 95% confidence) despite the small fractional orbital coverage of the observations. The absolute H-band magnitude of HD 47127 B is fainter than the benchmark T dwarfs HD 19467 B and Gl 229 B but brighter than Gl 758 B and HD 4113 C, suggesting a late-T spectral type. Altogether the mass limits for HD 47127 B from its dynamical mass and the substellar boundary imply a range of 67-78 MJup assuming it is single, although a preference for high masses of ≈100 MJup from dynamical constraints hints at the possibility that HD 47127 B could itself be a binary pair of brown dwarfs or that another massive companion resides closer in. Regardless, HD 47127 B will be an excellent target for more refined orbital and atmospheric characterization in the future.

Keywords: Brown dwarfs, Substellar companion stars, Companion stars, T dwarfs
Abundance Patterns of α and Neutron-capture Elements in the Helmi Stream. We identified eight additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and Gaia EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with parameters determined from high-resolution spectroscopy and spanning a considerably wider (by ∼0.5 dex) metallicity interval (- 2.5 ≲ [Fe/H] &lt; - 1.0) than previously reported. Our study focuses on α (Mg and Ca) and neutron-capture (Ba and Eu) elements. We find that the chemistry of HStr is typical of dwarf spheroidal (dSph) galaxies, in good agreement with previous N-body simulations of this merging event. Stars of HStr constitute a clear declining sequence in [α/Fe] for increasing metallicity up to [Fe/H] ∼ -1.0. Moreover, stars of HStr show a median value of +0.5 dex for [Eu/Fe] with a small dispersion (±0.1 dex). Every star analyzed with [Fe/H] &lt; -1.2 belongs to the r-process enhanced ([Eu/Fe] &gt; +0.3 and [Ba/Eu] &lt; 0.0) metal-poor category, providing remarkable evidence that, at such a low-metallicity regime, stars of HStr experienced enrichment in neutron-capture elements predominantly via r-process nucleosynthesis. Finally, the extended metallicity range also suggests an increase in [Ba/Eu] for higher [Fe/H], in conformity with other surviving dwarf satellite galaxies of the Milky Way.

Keywords: Milky Way formation, Stellar populations, R-process, Dwarf galaxies, Milky Way dynamics, Chemical abundances, Milky Way stellar halo, Population II stars, Milky Way evolution
Binary Black Hole Mergers from Young Massive and Open Clusters: Comparison to GWTC-2 Gravitational Wave Data. Several astrophysical scenarios have been proposed to explain the origin of the population of binary black hole (BBH) mergers detected in gravitational waves by the LIGO/Virgo Collaboration. Among them, BBH mergers assembled dynamically in young massive and open clusters have been shown to produce merger rate densities consistent with LIGO/Virgo estimated rates. We use the results of a suite of direct, high-precision N-body evolutionary models of young massive and open clusters and build the population of BBH mergers, by accounting for both a cosmologically motivated model for the formation of young massive and open clusters and the detection probability of LIGO/Virgo. We show that our models produce dynamically paired BBH mergers that are well consistent with the observed masses, mass ratios, effective spin parameters, and final spins of the second Gravitational Wave Transient Catalog (GWTC-2).

Keywords: Gravitational wave detectors, Black holes, Kerr black holes, Stellar mass black holes, Gravitational wave sources, Gravitational wave astronomy, Rotating black holes, Gravitational waves, Astrophysical black holes
Evidence for r-process Delay in Very Metal-poor Stars. The abundances of r-process elements of very metal-poor stars capture the history of the r-process enrichment in the early stage of star formation in a galaxy. Currently, various types of astrophysical sites including neutron star mergers (NSMs), magneto-rotational supernovae, and collapsars, are suggested as the origin of r-process elements. The time delay between the star formation and the production of r-process elements is the key to distinguish these scenarios, with the caveat that the diffusion of r-process elements in the interstellar medium may induce the delay in r-process enrichment because r-process events are rare. Here we study the observed Ba abundance data of very metal-poor stars as the tracer of the early enrichment history of r-process elements. We find that the gradual increase of [Ba/Mg] with [Fe/H], which is remarkably similar among the Milky Way and classical dwarfs, Requires a significant time delay (100 Myr-1 Gyr) of r-process events from star formation rather than the diffusion-induced delay. We stress that this conclusion is robust to the assumption regarding s-process contamination in the Ba abundances because the sources with no delay would overproduce Ba at very low metallicities, even without the contribution from the s-process. Therefore, we conclude that sources with a delay, possibly NSMs, are the origins of r-process elements.

Keywords: Stellar abundances, R-process, Chemical abundances, Galaxy abundances, Nuclear astrophysics
How Sublimation Delays the Onset of Dusty Debris Disk Formation around White Dwarf Stars. Although numerous white dwarf stars host dusty debris disks, the temperature distribution of these stars differs significantly from the white dwarf population as a whole. Dusty debris disks exist exclusively around white dwarfs cooler than 27,000 K. This is all the more enigmatic given that the formation processes of dusty debris disks should favor younger, hotter white dwarfs, which likely host more dynamically unstable planetary systems. Here we apply a sophisticated material sublimation model to white dwarf systems to show that these statistics are actually a natural result of the interplay of thermal and tidal forces and how they define the circumstellar regions where dusty debris disks can form. We demonstrate that these processes tend to prevent stability against both sublimative destruction and reaccretion into planetesimals for rocky materials until white dwarfs cool to below ∼25,000-32,000 K, in agreement with the observed limit of ∼27,000 K. For pure water ice, this critical temperature is less than 2700 K (requiring a cooling age older the universe); this precludes pure water ice-rich debris disks forming through the accepted two-step mechanism. The critical temperature is size-dependent; more massive white dwarfs could potentially host dusty debris disks at warmer temperatures. Our model suggests that the location of the disks within the PG 0010+280, GD 56, GD 362, and PG 1541+651 systems are consistent with a forsterite-dominated olivine composition. We also find that very cool white dwarfs may simultaneously host multiple, independently formed dusty debris disks, consistent with observations of the LSPM J0207+3331 system.

Keywords: Exoplanet dynamics, White dwarf stars, Exoplanet astronomy, Circumstellar grains, Circumstellar dust, Debris disks
Storms, Variability, and Multiple Equilibria on Hot Jupiters. Observations of hot-Jupiter atmospheres show large variations in the location of the "hot spot" and the amplitude of spectral features. Atmospheric flow simulations using the commonly employed forcing and initialization have generally produced a large, monolithic patch of nearly stationary hot area located eastward of the substellar point at high altitude. Here we perform high-resolution (T682) pseudospectral simulations that accurately capture small-scale eddies and waves inherent in hot-Jupiter atmospheres due to ageostrophy. The atmospheres contain a large number of intense storms over a wide range of scales, including the planetary scale. The latter sized storms dictate the large-scale spatial distribution and temporal variability of hot, as well as cold, regions over the planet. In addition, they exhibit quasi-periodic life cycles within multiple equilibrium states—all identifiable in the disk-integrated time series of the temperature flux.

Keywords: Hydrodynamical simulations, Internal waves, Exoplanets, Hot Jupiters, Exoplanet atmospheric variability, Planetary atmospheres, Planetary climates, Exoplanet detection methods, Lunar mountains, Exoplanet atmospheres
Investigating the Nature of MGRO J1908+06 with Multiwavelength Observations. The unidentified TeV source MGRO J1908+06, with emission extending from hundreds of GeV to beyond 100 TeV, is one of the most intriguing sources in the Galactic plane. MGRO J1908+06 spatially associates with an IceCube hotspot of neutrino emission. Although the hotspot is not significant yet, this suggests a possible hadronic origin of the observed gamma-ray radiation. Here we describe a multiwavelength analysis on MGRO J1908+06 to determine its nature. We identify, for the first time, an extended GeV source as the counterpart of MGRO J1908 + 06, discovering possibly associated molecular clouds (MCs). The GeV spectrum shows two well-differentiated components: a soft spectral component below ∼10 GeV, and a hard one (Γ ∼ 1.6) above these energies. The lower-energy part is likely associated with the dense MCs surrounding the supernova remnant (SNR) G40.5-0.5, whereas the higher-energy component, which connects smoothly with the spectrum observed in TeV range, resembles the inverse Compton emission observed in relic pulsar wind nebulae. This simple scenario seems to describe the data satisfactorily, but raises questions about the interpretation of the emission at hundreds of TeV. In this scenario, no detectable neutrino flux would be expected.

Keywords: Rotation powered pulsars, Gamma-ray sources, Molecular clouds, Supernova remnants, Gamma-ray astronomy
Discovery of a Highly Neutronized Ejecta Clump in the Type Ia Supernova Remnant 3C 397. The supernova remnant (SNR) 3C 397 is thought to originate from a Type Ia supernova (SN Ia) explosion of a near-Chandrasekhar-mass (MCh) progenitor, based on the enhanced abundances of Mn and Ni revealed by previous X-ray study with Suzaku. Here we report follow-up XMM-Newton observations of this SNR, conducted with the aim of investigating the detailed spatial distribution of the Fe-peak elements. We have discovered an ejecta clump with extremely high abundances of Ti and Cr, in addition to Mn, Fe, and Ni, in the southern part of the SNR. The Fe mass of this ejecta clump is estimated to be ∼0.06 M☉, under the assumption of a typical Fe yield for SNe Ia (i.e., ∼0.8 M☉). The observed mass ratios among the Fe-peak elements and Ti require substantial neutronization that is achieved only in the innermost regions of a near-MCh SN Ia with a central density of ρc ∼ 5 × 109 g cm-3, significantly higher than typically assumed for standard near-MCh SNe Ia (ρc ∼ 2 × 109 g cm-3). The overproduction of the neutron-rich isotopes (e.g., 50Ti and 54Cr) is significant in such high-ρc SNe Ia, with respect to the solar composition. Therefore, if 3C 397 is a typical high-ρc near-MCh SN Ia remnant, the solar abundances of these isotopes could be reproduced by the mixture of the high- and low-ρc near-MCh and sub-MCh Type Ia events, with ≲20% being high-ρc near-MCh.

Keywords: Supernova remnants
A Radio Quasi-periodic Oscillation of 176 days in the Radio-loud Narrow-line Seyfert 1 Galaxy J0849+5108. We analyze the 11 yr long-term light curve of the Radio-loud Narrow-line Seyfert 1 galaxy J0849+5108 and the nearly simultaneous γ-ray data of the source. The data were obtained with the Owens Valley Radio Observatory 40 m telescope at 15 GHz and with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope, respectively. A quasi-periodic oscillation (QPO) signal at a significance of &gt;5σ is found in the radio light curve, but no similar modulation is seen in the γ-ray light curve. The QPO signal was present for 21 cycles, the longest among the reported radio QPOs, and likely disappeared after 2019 January 16. Different mechanisms proposed to explain the observed QPOs in active galactic nuclei (AGNs) are discussed for this QPO case. Either a secular instability in the inner accretion disk or a helical structure in the jet of J0849+5108 may explain the radio QPO, while for the latter scenario the jet has to be collimated up to ~200 pc, similar to that seen in the nearby AGN M87. It will be of interest to keep monitoring the source at radio frequencies, seeing whether similar QPO signals appear again.

Keywords: Active galactic nuclei, Radio jets, Periodic orbit
The Compact UV Size of Green Pea Galaxies As Local Analogs of High-redshift Lyα-Emitters. We study the dependence of Lyα escape from galaxies on UV continuum size and luminosity using a sample of 40 Green Pea (GP) galaxies, which are the best local analogs of high-redshift Lyα emitters (LAEs). We use the Cosmic Origins Spectrograph near-ultraviolet images from the Hubble Space Telescope to measure the UV size and luminosity with 0"047 spatial resolution. Like most galaxies the GPs show a log-normal size distribution. They also show a positive correlation between size and UV-continuum luminosity. The slope of the size-continuum luminosity relation for GPs is consistent with those of continuum-selected star-forming galaxies (SFGs) at low and high redshifts. A distinctive feature of GPs is a very compact typical radius of 0.33 kpc with a population spread (1σ) of 0.19 kpc. The peak of the size distribution and the intercept of the size-luminosity relation of GPs are noticeably smaller than those of continuum-selected SFGs at similar redshifts. There are statistically significant anticorrelations found between the circularized half-light radius (rcir,50), the Lyα equivalent width (EW(Lyα)), and the Lyα escape faction ( ${f}_{{esc}}^{{Ly}\alpha }$ ), suggesting that small UV-continuum radii are crucial for Lyα emission. GPs and high-redshift LAEs have similar sizes, once spatial resolution effects are properly considered. Our results show that a compact small size is crucial for escape of Lyα photons, and that Lyα emitters show constant characteristic size independent of their redshift.

Keywords: Starburst galaxies, Galaxy formation, Compact galaxies, Galaxy structure, Emission line galaxies, Star formation, Galaxy evolution, Lyman-alpha galaxies, Reionization