Sazuna/UAT_keywords huggingface dataset:
In Situ Evidence of Ion Acceleration between Consecutive Reconnection Jet Fronts. Processes driven by unsteady reconnection can efficiently accelerate particles in many astrophysical plasmas. An example is the reconnection jet fronts in an outflow region. We present evidence of suprathermal ion acceleration between two consecutive reconnection jet fronts observed by the Magnetospheric Multiscale mission in the terrestrial magnetotail. An earthward propagating jet is approached by a second faster jet. Between the jets, the thermal ions are mostly perpendicular to magnetic field, are trapped, and are gradually accelerated in the parallel direction up to 150 keV. Observations suggest that ions are predominantly accelerated by a Fermi-like mechanism in the contracting magnetic bottle formed between the two jet fronts. The ion acceleration mechanism is presumably efficient in other environments where jet fronts produced by variable rates of reconnection are common and where the interaction of multiple jet fronts can also develop a turbulent environment, e.g., in stellar and solar eruptions.

Keywords: Space plasmas, Solar magnetic reconnection, Plasma jets
The Radio Luminosity-risetime Function of Core-collapse Supernovae. We assemble a large set of 2-10 GHz radio flux density measurements and upper limits of 294 different supernovae (SNe), from the literature and our own and archival data. Only 31% of SNe were detected. We characterize the SN radio lightcurves near the peak using a two-parameter model, with tpk being the time to rise to a peak and Lpk the spectral luminosity at that peak. Over all SNe in our sample at D &lt; 100 Mpc, we find that tpk = 101.7±0.9 days and that Lpk = 1025.5±1.6 erg s-1 Hz-1, and therefore that generally 50% of SNe will have Lpk &lt; 1025.5 erg s-1 Hz-1. These Lpk values are ∼30 times lower than those for only detected SNe. Types Ib/c and II (excluding IIn's) have similar mean values of Lpk but the former have a wider range, whereas Type IIn SNe have ∼10 times higher values with Lpk = 1026.5±1.1 erg s-1 Hz-1. As for tpk, Type Ib/c have tpk of only 101.1±0.5 days while Type II have tpk = 101.6±1.0 and Type IIn the longest timescales with tpk = 103.1±0.7 days. We also estimate the distribution of progenitor mass-loss rates, $\dot{M}$ , and find that the mean and standard deviation of ${\mathrm{log}}_{10}(\dot{M}/[{M}_{\odot }\,{\mathrm{yr}}^{-1}])$ are -5.4 ± 1.2 (assuming vwind = 1000 km s-1) for Type Ib/c SNe, and -6.9 ± 1.4 (assuming vwind = 10 km s-1) for Type II SNe excluding Type IIn.

Keywords: Core-collapse supernovae, Radio transient sources
Probing the Cold Deep Depths of the California Molecular Cloud: The Icy Relationship between CO and Dust. We study the relationship between molecular gas and dust in the California Molecular Cloud over an unprecedented dynamic range of cloud depth (AV = 3-60 mag). We compare deep Herschel-based measurements of dust extinction with observations of the 12CO, 13CO, and C18O J = 2 - 1 lines on sub-parsec scales across the cloud. We directly measure the ratio of CO integrated intensity to dust extinction to derive the CO X-factor at over 105 independent locations in the cloud. Confirming an earlier study, we find that no single 12CO X-factor can characterize the molecular gas in the cold (Tdust ≤ 20) regions of the cloud that account for most of its mass. We are able to derive a single-valued X-factor for all three CO isotopologues in the warm (Tdust &gt; 25 K) material that is spatially coincident with an H II region surrounding the star LkHα 101. We derive the LTE CO column densities for 13CO and C18O since we find both lines are relatively optically thin. In the warm cloud material, CO is completely in the gas phase and we are able to recover the total 13CO and C18O abundances. Using CO abundances and deep Herschel observations, we measure lower bounds to the freeze-out of CO onto dust across the whole cloud, finding some regions having CO depleted by a factor of &gt;20. We construct the first maps of depletion that span the extent of a giant molecular cloud. Using these maps we identify 75 depletion-defined cores and discuss their physical nature.

Keywords: Star forming regions, Chemical abundances, Galactic and extragalactic astronomy, Giant molecular clouds, Interstellar medium, H II regions
The Linkage between the Core Mass and the Magnetic Field of an Extrasolar Giant Planet from Future Radio Observations. Close-in gas giants are expected to have a strong magnetic field of ∼10-100 G. Magnetic fields in extrasolar giant planets are detectable by future radio observations in ≳10 MHz and the spectropolarimetry of atomic lines. In contrast, the elusive interiors of exoplanets remain largely unknown. Here we consider the possibility of inferring the existence of the innermost cores of extrasolar giant planets through the detection of planetary magnetic fields. We simulated the long-term thermal evolution of close-in giant planets with masses of 0.2-10 MJup to estimate their magnetic field strengths. A young, massive gas giant tends to have a strong magnetic field. The magnetic field strength of a hot Jupiter is insensitive to its core mass, whereas the core strongly affects the emergence of a planetary dynamo in a hot Saturn. No dynamo-driven magnetic field is generated in a hot Saturn with no core or a small one until ∼10-100 Myr if metallization of hydrogen occurs at ≳1-1.5 Mbar. The magnetic field strength of an evolved gas giant after ∼100 Myr is almost independent of the stellar incident flux. Detecting the magnetic field of a young, hot Saturn as a good indicator of its core may be challenging because of the weakness of radio signals and the shielding effect of plasma in Earth's ionosphere. Hot Jupiters with ≳0.4 MJup can be promising candidates for future ground-based radio observations.

Keywords: Magnetic fields, Planetary interior, Exoplanets
Gravitational Collider Physics via Pulsar-Black Hole Binaries. We propose to use pulsar-black hole binaries as a probe of gravitational collider physics. Induced by the gravitation of the pulsar, the atomic transitions of the boson cloud around the black hole backreact on the orbital motion. This leads to the deviation of the binary period decrease from that predicted by general relativity, which can be directly probed by the Rømer delay of pulsar times of arrival. The sensitivity and accuracy of this approach are estimated for two typical atomic transitions. It is shown that once the transitions happen within the observable window, the pulsar-timing accuracy is almost always sufficient to capture the resonance phenomenon.

Keywords: Black hole physics, Black holes, High energy astrophysics, Millisecond pulsars, Dark matter
The R-Process Alliance: Chemodynamically Tagged Groups of Halo r-process-enhanced Stars Reveal a Shared Chemical-evolution History. We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a 10-fold increase in size relative to that previously considered by Roederer et al. and, by design, covers a larger range of r-process-element enrichment levels. We test a number of clustering analysis methods on the derived orbital energies and other dynamical parameters for this sample, ultimately deciding on application of the HDBSCAN algorithm, which obtains 30 individual chemodynamically tagged groups (CDTGs); 21 contain between 3 and 5 stars, and 9 contain between 6 and 12 stars. Even though the clustering was performed solely on the basis of their dynamical properties, the stars in these CDTGs exhibit statistically significant similarities in their metallicity ([Fe/H]), carbonicity ([C/Fe]), and neutron-capture element ratios ([Sr/Fe], [Ba/Fe], and [Eu/Fe]). These results demonstrate that the RPE stars in these CDTGs have likely experienced common chemical-evolution histories, presumably in their parent satellite galaxies or globular clusters, prior to being disrupted into the Milky Way's halo. We also confirm the previous claim that the orbits of the RPE stars preferentially exhibit pericentric distances that are substantially lower than the present distances of surviving ultrafaint dwarf and canonical dwarf spheroidal galaxies, consistent with the disruption hypothesis. The derived dynamical parameters for several of our CDTGs indicate their association with previously known substructures, dynamically tagged groups, and RPE groups.

Keywords: Stellar populations, Stellar abundances, R-process, Dwarf galaxies, Stellar dynamics, Milky Way stellar halo
Optical Identification and Spectroscopy of Supernova Remnants in the Galaxy M51. Using a combination of ground-based and Hubble Space Telescope imaging, we have constructed a catalog of 179 supernova remnants (SNRs) and SNR candidates in the nearby spiral galaxy M51. Follow-up spectroscopy of 66 of the candidates confirms that 61 of these are SNRs and suggests that the vast majority of the unobserved objects are SNRs as well. A total of 55 of the candidates are coincident with (mostly soft) X-ray sources identified in deep Chandra observations of M51; searching the positions of other soft X-ray sources resulted in several additional possible optical candidates. There are 16 objects in the catalog coincident with known radio sources. None of the sources with spectra show the high velocities (≳500 km s-1) characteristic of young, ejecta-dominated SNRs like Cas A; instead, most if not all appear to be middle-aged SNRs. The general properties of the SNRs, size distribution and spectral characteristics, resemble those in other nearby spiral galaxies, notably M33, M83, and NGC 6946, where similar samples exist. However, the spectroscopically observed [N II]:Hα ratios appear to be significantly higher than in any of these other galaxies. Although we have explored various ideas to explain the high ratios in M51, none of the explanations appear to be satisfactory. * Based in part 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, Incorporated, under NASA contract NAS5-26555. Support for program Nos. 14638 and 15216 was provided through a grant from the STScI under NASA contract NAS5-26555.

Keywords: Supernova remnants, Spiral galaxies, Interstellar medium, Nebulae
Revisiting the Complex Kinematics of Ionized Gas at the Central Region of NGC 1068: Evidence of an Additional Active Galactic Nucleus?. We present a spatially resolved analysis of ionized gas at the nuclear region of the nearby galaxy NGC 1068. While NGC 1068 has been known to have gas outflows driven by its active galactic nucleus (AGN), more complex kinematical signatures were recently reported, which were inconsistent with rotation or simple biconical outflows. To account for the nature of gas kinematics, we performed a spatially resolved kinematical study, finding a morphologically symmetric pair of approaching and receding gas blobs in the northeast region. The midpoint of the two blobs is located at a distance of 180 pc from the nucleus in the projected plane. The ionized gas at the midpoint shows zero velocity and high velocity dispersion, which are characteristics of an outflow-launching position, as the two sides of a bicone, i.e., approaching and receding outflows are superposed on the line of sight, leading to no velocity shift but high velocity dispersion. We investigate the potential scenario of an additional AGN based on a multiwavelength data set. While there are other possibilities, i.e., X-ray binary or supernova shock, the results from optical spectropolarimetry analysis are consistent with the presence of an additional AGN, which likely originates from a minor merger.

Keywords: Active galactic nuclei, Spectroscopy
Modeling Nitrogen Fractionation in the Protoplanetary Disk around TW Hya: Model Constraints on Grain Population and Carbon-to-oxygen Elemental Abundance Ratio. Observations conducted using the Atacama Large Millimeter/submillimeter Array on the protoplanetary disk around TW Hya show the nitrogen fractionation of HCN molecules in HC14N/HC15N ∼ 120 at a radius of ∼20 au. In this study, we investigate the physical and chemical conditions that control this nitrogen fractionation process. To this end, a new disk model was developed, in which the isotope-selective photodissociation of N2 and isotope-exchange chemical reactions have been incorporated. Our model can successfully reproduce the observed HCN column density when the elemental abundances of gas-phase carbon and oxygen are depleted by two orders of magnitude relative to those in the interstellar medium and carbon is more abundant than oxygen ([C/O]elem &gt; 1). The isotope-selective photodissociation of N2 is the dominant nitrogen fractionation process in our models. The observed HC14N/HC15N ratio, which increases outwards, can also be reproduced by the model by assuming that the small dust grains in the atmosphere of the outer disk are depleted more than those in the inner disk. This is consistent with grain evolution models, according to which small dust grains are continuously replenished in the inner disk due to fragmentation of the large dust grains that radially drift from the outer disk.

Keywords: Protoplanetary disks, Astrochemistry
The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts. II. Waiting-Mode Bursts Simultaneously Detected by Swift/BAT. In the second part of The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts (the first part: Tsvetkova et al. 2017; T17), we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected simultaneously by the Konus-Wind (KW) experiment (in the waiting mode) and by the Swift/BAT (BAT) telescope during the period from 2005 January to the end of 2018. By taking advantage of the high sensitivity of BAT and the wide spectral band of KW, we were able to constrain the peak spectral energies, the broadband energy fluences, and the peak fluxes for the joint KW-BAT sample of 167 weak, relatively soft GRBs (including four short bursts). Based on the GRB redshifts, which span the range 0.04 ≤ z ≤ 9.4, we estimate the rest frame, isotropic-equivalent energy, and peak luminosity. For 14 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. This work extends the sample of KW GRBs with known redshifts to 338 GRBs, the largest set of cosmological GRBs studied to date over a broad energy band. With the full KW sample, accounting for the instrumental bias, we explore GRB rest-frame properties, including hardness-intensity correlations, GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which we find to be in general agreement with those reported in T17 and other previous studies.

Keywords: Gamma-ray bursts, Astronomy data analysis, Catalogs
Eppur è piatto? The Cosmic Chronometers Take on Spatial Curvature and Cosmic Concordance. The question of whether cosmic microwave background (CMB) temperature and polarization data from Planck favor a spatially closed universe with curvature parameter ΩK &lt; 0 has been the subject of recent intense discussions. Attempts to break the geometrical degeneracy combining Planck data with external data sets such as baryon acoustic oscillation (BAO) measurements all point toward a spatially flat universe at the cost of significant tensions with Planck, which makes the resulting data set combination problematic. Settling this issue requires identifying a data set that can break the geometrical degeneracy while avoiding these tensions. We argue that cosmic chronometers (CCs), measurements of the expansion rate H(z) from the relative ages of massive early-type passively evolving galaxies, are the data set we are after. Furthermore, CCs come with the additional advantage of being virtually free of cosmological model assumptions. Combining Planck 2018 CMB temperature and polarization data with the latest CCs, we break the geometrical degeneracy and find ΩK = -0.0054 ± 0.0055, consistent with a spatially flat universe and competitive with the Planck+BAO constraint. Our results are stable against minimal parameter space extensions and CC systematics, and we find no substantial tension between Planck and CC data within a nonflat universe, making the resulting combination reliable. Our results allow us to assert with confidence that the universe is spatially flat to the ${ \mathcal O }({10}^{-2})$ level, a finding that might possibly settle the ongoing spatial curvature debate and lends even more support to the already very successful inflationary paradigm.

Keywords: Cosmological parameters, Observational cosmology, Galaxy ages, Cosmic background radiation, Galaxies
Observational Evidence for Enhanced Black Hole Accretion in Giant Elliptical Galaxies. We present a study of the relationship between black hole accretion rate (BHAR) and star formation rate (SFR) in a sample of giant elliptical galaxies. These galaxies, which live at the centers of galaxy groups and clusters, have star formation and black hole activity that is primarily fueled by gas condensing out of the hot intracluster medium. For a sample of 46 galaxies spanning five orders of magnitude in BHAR and SFR, we find a mean ratio of ${\mathrm{log}}_{10}(\mathrm{BHAR}/\mathrm{SFR})=-1.45\pm 0.2$ , independent of the methodology used to constrain both SFR and BHAR. This ratio is significantly higher than most previously published values for field galaxies. We investigate whether these high BHAR/SFR ratios are driven by high BHAR, low SFR, or a different accretion efficiency in radio galaxies. The data suggest that the high BHAR/SFR ratios are primarily driven by boosted black hole accretion in spheroidal galaxies compared to their disk counterparts. We propose that the angular momentum of the cool gas is the primary driver in suppressing BHAR in lower-mass galaxies, with massive galaxies accreting gas that has condensed out of the hot phase on nearly radial trajectories. Additionally, we demonstrate that the relationship between specific BHAR and SFR (sBHAR and sSFR) has much less scatter over six orders of magnitude in both parameters, due to competing dependence on morphology between the MBH-M* and BHAR-SFR relations. In general, active galaxies selected by typical techniques have sBHAR/sSFR ∼ 10, while galactic nuclei with no clear AGN signatures have sBHAR/sSFR ∼ 1, consistent with a universal MBH-Mspheroid relation.

Keywords: Galaxy clusters, Black hole physics, Supermassive black holes, Giant elliptical galaxies, Active galactic nuclei, Galaxy groups, X-ray active galactic nuclei, Radio active galactic nuclei, Brightest cluster galaxies
Filament Rotation in the California L1482 Cloud. We analyze the gas mass distribution, the gas kinematics, and the young stellar objects of the California Molecular Cloud L1482 filament. The mean Gaia DR2 YSO distance is ${511}_{-16}^{+17}$ pc. In terms of the gas, the line-mass (M/L) profiles are symmetric scale-free power laws consistent with cylindrical geometry. We calculate the gravitational potential and field profiles based on these. Our IRAM 30 m multi-tracer position-velocity diagrams highlight twisting and turning structures. We measure the C18O velocity profile perpendicular to the southern filament ridgeline. The profile is regular, confined (projected r ≲ 0.4 pc), antisymmetric, and, to first order, linear, with a break at r ∼ 0.25 pc. We use a simple solid-body rotation toy model to interpret it. We show that the centripetal force, compared to gravity, increases toward the break; when the ratio of forces approaches unity, the profile turns over, just before the implied filament breakup. The timescales of the inner (outer) gradients are ∼0.7 (6.0) Myr. The timescales and relative roles of gravity to rotation indicate that the structure is stable, long lived (∼a few times 6 Myr), and undergoing outside-in evolution. This filament has practically no star formation, a perpendicular Planck plane-of-the-sky magnetic field morphology, and 2D "zig-zag" morphology, which together with the rotation profile lead to the suggestion that the 3D shape is a "corkscrew" filament. These results, together with results in other regions, suggest evolution toward higher densities as rotating filaments shed angular momentum. Thus, magnetic fields may be an essential feature of high-mass (M ∼ 105 M⊙) cloud filament evolution toward cluster formation.

Keywords: Interstellar filaments, Interstellar dynamics, Molecular clouds, Interstellar magnetic fields, Giant molecular clouds, Young stellar objects
The Red Supergiant Binary Fraction as a Function of Metallicity in M31 and M33. Recent work measuring the binary fraction of evolved red supergiants (RSGs) in the Magellanic Clouds points to a value between 15% and 30%, with the majority of the companions being unevolved B-type stars as dictated by stellar evolution. Here I extend this research to the Local Group galaxies M31 and M33 and investigate the RSG binary fraction as a function of metallicity. Recent near-IR photometric surveys of M31 and M33 have led to the identification of a complete sample of RSGs down to a limiting $\mathrm{log}L/{L}_{\odot }\geqslant 4.2$ . To determine the binary fraction of these M31 and M33 RSGs, I used a combination of newly obtained spectroscopy to identify single RSGs and RSG+OB binaries, as well as archival UV, visible, and near-IR photometry to probabilistically classify RSGs as either single or binary based on their colors. I then adjusted the observed RSG+OB binary fraction to account for observational biases. The resulting RSG binary fraction in M33 shows a strong dependence on galactocentric distance, with the inner regions having a much higher binary fraction ( ${41.2}_{-7.3}^{+12.0} \% $ ) than the outer regions ( ${15.9}_{-1.9}^{+12.4} \% $ ). Such a trend is not seen in M31; instead, the binary fraction in lightly reddened regions remains constant at ${33.5}_{-5.0}^{+8.6} \% $ . I conclude that the changing RSG binary fraction in M33 is due to a metallicity dependence, with higher-metallicity environments having higher RSG binary fractions. This dependence most likely stems not from changes in the physical properties of RSGs due to metallicity but from changes in the parent distribution of OB binaries.

Keywords: Metallicity, Binary stars, Red supergiant stars, Massive stars, OB stars, Triangulum Galaxy, Andromeda Galaxy
Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres. We investigate the temporal evolution of an axisymmetric magnetosphere around a rapidly rotating stellar-mass black hole by applying a two-dimensional particle-in-cell simulation scheme. Adopting homogeneous pair production and assuming that the mass accretion rate is much less than the Eddington limit, we find that the black hole's rotational energy is preferentially extracted from the middle latitudes and that this outward energy flux exhibits an enhancement that lasts approximately 160 dynamical timescales. It is demonstrated that the magnetohydrodynamic approximations cannot be justified in such a magnetically dominated magnetosphere because Ohm's law completely breaks down and the charge-separated electron-positron plasmas are highly nonneutral. An implication is given regarding the collimation of relativistic jets.

Keywords: General relativity, Stellar magnetic fields, Astronomical simulations, Kerr black holes