Sazuna/UAT_keywords huggingface dataset:
Meso-scale Instability Triggered by Dust Feedback in Dusty Rings: Origin and Observational Implications. High spatial resolution observations of protoplanetary disks by ALMA have revealed many substructures that are providing interesting constraints on disk physics as well as dust dynamics, both of which are essential for understanding planet formation. We carry out high-resolution, 2D global hydrodynamic simulations, including the effects of dust feedback, to study the stability of dusty rings. When the ring edges are relatively sharp and the dust surface density becomes comparable to the gas surface density, we find that dust feedback enhances the radial gradients of both the azimuthal velocity profile and the potential vorticity profile at the ring edges. This eventually leads to instabilities on meso-scales (spatial scales of several disk scale heights), causing dusty rings to be populated with many compact regions with highly concentrated dust densities. We also produce synthetic dust emission images using our simulation results and discuss the comparison between simulations and observations.

Keywords: Hydrodynamical simulations, Hydrodynamics, Radiative transfer simulations, Protoplanetary disks, Submillimeter astronomy, Planet formation
An XMM-Newton X-Ray View of Supernova Remnant W49B: Revisiting Its Recombining Plasmas and Progenitor Type. We present a comprehensive X-ray spectroscopy and imaging study of supernova remnant W49B using archival XMM-Newton observations. The overionization state of the shocked ejecta in W49B is clearly indicated by the radiative recombination continua of Si XIV, S XV, and Fe XXV, combined with the Lyα lines of Ca and Fe. The line flux images of W49B indicate high emission measures of the central bar-like region for almost all of the emission lines, while the equivalent width maps reveal a stratified structure for the metal abundance distributions. The global spectrum of W49B is well reproduced by a model containing one collisional ionization equilibrium (CIE) plasma component and two recombining plasma (RP) components. The CIE plasma represents the shocked interstellar medium, which dominates the X-ray emitting volume in W49B with a mass ∼450 ${M}_{\odot }$ . The two RP components with a total mass ∼4.6 ${M}_{\odot }$ are both dominated by the ejecta material, but characterized by different electron temperatures (∼1.60 and ∼0.64 keV). The recombination ages of the RP components are estimated as ∼6000 yr and ∼3400 yr, respectively. We then reveal the possibility of a thermal conduction origin for the high-temperature RP in W49B by calculating the conduction timescale. The metal abundance ratios of the ejecta in W49B are roughly consistent with a core-collapse explosion model with a ≲15 ${M}_{\odot }$ progenitor, except for a rather high Mn/Fe. A Type Ia origin can explain the Mn abundance, while it predicts much higher ejecta masses than observed values for all of the metal species considered in our analysis.

Keywords: Supernova remnants, X-ray astronomy, Interstellar medium
Local Molecular Gas toward the Aquila Rift Region. We present the results of a ∼250 square degrees CO mapping (+26° ≲ l ≲ +50° and -5° ≲ b ≲ +5°) toward the Aquila Rift region at a spatial resolution of ∼50″ and a grid spacing of 30″. The high dynamic range CO maps with a spectral resolution of ∼0.2 km s-1 display highly structured molecular cloud (MC) morphologies with valuable velocity information, revealing complex spatial and dynamical features of the local molecular gas. In combination with the MWISP CO data and the Gaia DR2, distances of the main MC structures in the local ISM are well determined toward the Aquila Rift region. We find that the total MC mass within 1 kpc is about ≳4.1 × 105 ${M}_{\odot }$ in the whole region. In fact, the mass of the molecular gas is dominated by the W40 giant molecular cloud (GMC) at ∼474 pc (∼1.4 × 105 ${M}_{\odot }$ ) and the GMC complex G036.0+01.0 at ∼560-670 pc (∼2.0 × 105 ${M}_{\odot }$ ), while the MCs at ∼220-260 pc have gas masses of ∼102-103 ${M}_{\odot }$ . Interestingly, an ∼80 pc long filamentary MC G044.0-02.5 at a distance of ∼404 pc shows a systematic velocity gradient along and perpendicular to the major axis of the filament. The H I gas with enhanced emission has similar spatial morphologies and velocity features compared to the corresponding CO structure, indicating that large-scale converging H I flows are probably responsible for the formation of the MC. Meanwhile, the long filamentary MC consists of many sub-filaments with lengths ranging from ∼0.5 pc to several pc, as well as prevalent networks of filaments in other large-scale local MCs.

Keywords: Interstellar molecules, Stellar-interstellar interactions, Interstellar dynamics, Surveys, Molecular clouds, Star formation, Interstellar medium
Sandblasting the r-process: Spallation of Ejecta from Neutron Star Mergers. Neutron star mergers (NSMs) are rapid neutron-capture (r-process) nucleosynthesis sites that expel matter at high velocities, from 0.1c to as high as 0.6c. Nuclei ejected at these speeds are sufficiently energetic to initiate spallation nuclear reactions with interstellar medium (ISM) particles. We adopt a thick-target model for the propagation of high-speed heavy nuclei in the ISM, similar to the transport of cosmic rays. We find that spallation may create observable perturbations to NSM isotopic abundances, particularly around the low-mass edges of the r-process peaks where neighboring nuclei have very different abundances. The extent to which spallation modifies the final NSM isotopic yields depends on: (1) the ejected abundances, which are determined by the NSM astrophysical conditions and the properties of nuclei far from stability, (2) the ejecta velocity distribution and propagation in interstellar matter, and (3) the spallation cross sections. Observed solar and stellar r-process yields could thus constrain the velocity distribution of ejected neutron star matter, assuming NSMs are the dominant r-process source. We suggest avenues for future work, including measurement of relevant cross sections.

Keywords: Nucleosynthesis, Nuclear reaction cross sections, R-process, Nuclear abundances, Compact binary stars, Cosmic rays
Localized Magnetic-field Structures and Their Boundaries in the Near-Sun Solar Wind from Parker Solar Probe Measurements. One of the discoveries of the Parker Solar Probe during its first encounters with the Sun is ubiquitous presence of relatively small-scale structures standing out as sudden deflections of the magnetic field. They were named "switchbacks" since some of them show a full reversal of the radial component of the magnetic field and then return to "regular" conditions. We carried out an analysis of three typical switchback structures having different characteristics: I. Alfvénic structure, where the variations of the magnetic field components take place while conserving the magnitude of the magnetic field; II. Compressional structure, where the magnitude of the field varies together with changes of its components; and III. Structure manifesting full reversal of the magnetic field, presumably Alfvén, which is an extremal example of a switchback. We analyzed the properties of the magnetic fields of these structures and of their boundaries. Observations and analyses lead to the conclusion that they represent localized twisted magnetic tubes moving with respect to surrounding plasma. An important feature is the existence of a relatively narrow boundary layer at the surface of the tube that accommodates flowing currents. These currents are closed on the surface of the structure and typically have comparable azimuthal and tube-axis-aligned components. They are supported by the presence of an effective electric field due to strong gradients of the density and ion plasma pressure. The ion beta is typically larger inside the structure than outside. The surface of the structure may also accommodate electromagnetic waves that assist particles in carrying currents.

Keywords: Alfven waves
Dust Attenuation Curve for Local Subgalactic Star-forming Regions. We compile a sample of about 157,000 spaxels from the Mapping Nearby Galaxies at the Apache Point Observatory (MaNGA) survey to derive the average dust attenuation curve for subgalactic star-forming regions of local star-forming galaxies (SFGs) in the optical wavelength, following the method of Calzetti et al. We obtain a ${D}_{n}(4000)$ -independent average attenuation curve for spaxels with 1.1 ≤ Dn(4000) &lt; 1.3, which is similar to the one derived from either local starbursts or normal SFGs. We examine whether and how the shape of the average attenuation curve changes with several local and global physical properties. For spaxels with 1.2 ≤ Dn(4000) &lt; 1.3, we find no dependence on either local or global physical properties for the shape of the average attenuation curve. However, for spaxels with younger stellar population (1.1 ≤ Dn(4000) &lt; 1.2), shallower average attenuation curves are found for star-forming regions with smaller stellar mass surface density, smaller star formation rate surface density, or those residing in the outer region of galaxies. These results emphasize the risk of using one single attenuation curve to correct the dust reddening for all type of star-forming regions, especially for those with fairly young stellar population.

Keywords: Interstellar dust extinction, Galaxy evolution, Interstellar medium, H II regions, Galaxies
Spectroscopy of Broad Absorption Line Quasars at 3 ≲ Z ≲ 5. I. Evidence for Quasar Winds Shaping Broad/Narrow Emission Line Regions. We present an observational study of 22 broad absorption line quasars (BAL QSOs) at $3\lesssim z\lesssim 5$ based on optical/near-IR spectroscopy, aiming to investigate quasar winds and their effects. The near-IR spectroscopy covers the Hβ and/or Mg II broad emission lines (BELs) for these quasars, allowing us to estimate their central black hole (BH) masses in a robust way. We found that our BAL QSOs, on average, do not have a higher Eddington ratio than that from non-BAL QSOs matched in redshift and/or luminosity. In a subset consisting of seven strong BAL QSOs possessing subrelativistic BAL outflows, we see the prevalence of large C IV BEL blueshift (∼3100 km s-1) and weak [O III] emission (particularly the narrow [O III] λ5007 component), indicative of nuclear outflows affecting the narrow emission line (NEL) regions. In another subset consisting of 13 BAL QSOs having simultaneous observations of Mg II and Hβ, we found a strong correlation between 3000 and 5000 Å monochromatic luminosity, consistent with that from non-BAL QSOs matched in redshift and luminosity; however, there is no correlation between Mg II and Hβ in FWHM, likely due to nuclear outflows influencing the BEL regions. Our spectroscopic investigations offer strong evidence that the presence of nuclear outflows plays an important role in shaping the BEL/NEL regions of these quasars and, possibly, regulating the growth of central supermassive BHs. We propose that BEL blueshift and BALs could be different manifestations of the same outflow system viewed at different sight lines and/or phases.

Keywords: Supermassive black holes, Broad-absorption line quasar, Quasars
CHAOS IV: Gas-phase Abundance Trends from the First Four CHAOS Galaxies. The chemical abundances of spiral galaxies, as probed by H II regions across their disks, are key to understanding the evolution of galaxies over a wide range of environments. We present Large Binocular Telescope/Multi-Object Double Spectrographs spectra of 52 H II regions in NGC 3184 as part of the CHemical Abundances Of Spirals (CHAOS) project. We explore the direct-method gas-phase abundance trends for the first four CHAOS galaxies, using temperature measurements from one or more auroral-line detections in 190 individual H II regions. We find that the dispersion in ${T}_{e}-{T}_{e}$ relationships is dependent on ionization, as characterized by ${F}_{\lambda 5007}/{F}_{\lambda 3727}$ , and so we recommend ionization-based temperature priorities for abundance calculations. We confirm our previous results that [N II] and [S III] provide the most robust measures of electron temperature in low-ionization zones, while [O III] provides reliable electron temperatures in high-ionization nebula. We measure relative and absolute abundances for O, N, S, Ar, and Ne. The four CHAOS galaxies marginally conform with a universal O/H gradient, as found by empirical integral field unit studies when plotted relative to effective radius. However, after adjusting for vertical offsets, we find a tight universal N/O gradient of ${\alpha }_{{\rm{N}}/{\rm{O}}}=-0.33$ dex/Re with σtot. = 0.08 for Rg/Re &lt; 2.0, where N is dominated by secondary production. Despite this tight universal N/O gradient, the scatter in the N/O-O/H relationship is significant. Interestingly, the scatter is similar when N/O is plotted relative to O/H or S/H. The observable ionic states of S probe lower ionization and excitation energies than O, which might be more appropriate for characterizing abundances in metal-rich H II regions.

Keywords: Spiral galaxies, Galaxy chemical evolution, Interstellar abundances, Chemical abundances, Galaxy abundances, Galaxy evolution, Interstellar medium, Metallicity
Testing the Lamp-post and Wind Reverberation Models with XMM-Newton Observations of NGC 5506. The lamp-post geometry is often used to model X-ray data of accreting black holes. Despite its simple assumptions, it has proven to be powerful in inferring fundamental black hole properties such as the spin. Early results of X-ray reverberations showed support for such a simple picture, though wind reverberation models have also been shown to explain the observed delays. Here, we analyze new and old XMM-Newton observations of the variable Seyfert-1 galaxy NGC 5506 to test these models. The source shows an emission line feature around 6.7 keV that is delayed relative to harder and softer energy bands. The spectral feature can be modeled with either a weakly relativistic disk line or by scattering in distant material. By modeling both the spectral and timing signatures, we find that the reflection fraction needed to explain the lags is larger than that observed in the time-averaged spectrum, ruling out both static lamp-post and simple wind reverberation models.

Keywords: Supermassive black holes, High energy astrophysics, X-ray active galactic nuclei, Active galactic nuclei, Compact objects, Astrophysical black holes
An Ejecta Kinematics Study of Kepler's Supernova Remnant with High-resolution Chandra HETG Spectroscopy. We report our measurements of the bulk radial velocity from a sample of small, metal-rich ejecta knots in Kepler's supernova remnant (SNR). We measure the Doppler shift of the He-like Si Kα line-center energy in the spectra of these knots based on our Chandra High-Energy Transmission Grating Spectrometer observation to estimate their radial velocities. We estimate high radial velocities of up to ∼8000 km s-1 for some of these ejecta knots. We also measure proper motions for our sample based on the archival Chandra Advanced CCD Imaging Spectrometer data taken in 2000, 2006, and 2014. Our measured radial velocities and proper motions indicate that some of these ejecta knots are almost freely expanding after ∼400 yr since the explosion. The fastest moving knots show proper motions of up to ∼0"2 per year. Assuming that these high-velocity ejecta knots are traveling ahead of the forward shock of the SNR, we estimate the distance to Kepler's SNR d ∼ 4.4-7.5 kpc. We find that the ejecta knots in our sample have an average space velocity of Vs ∼ 4600 km s-1 (at a distance of 6 kpc). We note that 8 of the 15 ejecta knots from our sample show a statistically significant (at the 90% confidence level) redshifted spectrum, compared to only two with a blueshifted spectrum. This may suggest an asymmetry in the ejecta distribution in Kepler's SNR along the line of sight; however, a larger sample size is required to confirm this result.

Keywords: X-ray astronomy, Interstellar dynamics, Supernova remnants, Proper motions, Radial velocity
Three-dimensional Simulations of Magnetar-powered Superluminous Supernovae. A rapidly spinning magnetar in a young supernova (SN) can produce a superluminous transient by converting a fraction of its rotational energy into radiation. Here, we present the first three-dimensional hydrodynamical simulations ever performed of a magnetar-powered SN in the circumstellar medium formed by the ejection of the outer layers of the star prior to the blast. We find that hydrodynamical instabilities form on two scales in the ejecta, not just one as in ordinary core-collapse SNe: in the hot bubble energized by the magnetar and in the forward shock of the SN as it plows up ambient gas. Pressure from the bubble also makes the instabilities behind the forward shock more violent and causes more mixing in the explosion than in normal SNe, with important consequences for the light curves and spectra of the event that cannot be captured by one-dimensional models. We also find that the magnetar can accelerate Ca and Si to velocities of ∼12,000 $\mathrm{km}\,{{\rm{s}}}^{-1}$ and account for their broadened emission lines in observations. Our simulations also reveal that energy from even weak magnetars can accelerate iron-group elements deep in the ejecta to 5000-7000 $\mathrm{km}\,{{\rm{s}}}^{-1}$ and explain the high-velocity Fe observed at early times in some core-collapse SNe such as SN 1987A.

Keywords: Millisecond pulsars, Massive stars, Shocks, Supernova remnants, Magnetars, Astrophysical fluid dynamics, Supernovae
A Joint Fermi-GBM and LIGO/Virgo Analysis of Compact Binary Mergers from the First and Second Gravitational-wave Observing Runs. We present results from offline searches of Fermi Gamma-ray Burst Monitor (GBM) data for gamma-ray transients coincident with the compact binary coalescences observed by the gravitational-wave (GW) detectors Advanced LIGO and Advanced Virgo during their first and second observing runs. In particular, we perform follow-up for both confirmed events and low significance candidates reported in the LIGO/Virgo catalog GWTC-1. We search for temporal coincidences between these GW signals and GBM-triggered gamma-ray bursts (GRBs). We also use the GBM Untargeted and Targeted subthreshold searches to find coincident gamma-rays below the onboard triggering threshold. This work implements a refined statistical approach by incorporating GW astrophysical source probabilities and GBM visibilities of LIGO/Virgo sky localizations to search for cumulative signatures of coincident subthreshold gamma-rays. All search methods recover the short gamma-ray burst GRB 170817A occurring ∼1.7 s after the binary neutron-star merger GW170817. We also present results from a new search seeking GBM counterparts to LIGO single-interferometer triggers. This search finds a candidate joint event, but given the nature of the GBM signal and localization, as well as the high joint false alarm rate of 1.1 × 10-6 Hz, we do not consider it an astrophysical association. We find no additional coincidences.

Keywords: Gamma-ray bursts, Gravitational waves
An Unbiased ALMA Spectral Survey of the LkCa 15 and MWC 480 Protoplanetary Disks. The volatile contents of protoplanetary disks both set the potential for planetary chemistry and provide valuable probes of defining disk system characteristics such as stellar mass, gas mass, ionization, and temperature structure. Current disk molecular inventories are fragmented, however, giving an incomplete picture: unbiased spectral line surveys are needed to assess the volatile content. We present here an overview of such a survey of the protoplanetary disks around the Herbig Ae star MWC 480 and the T Tauri star LkCa 15 in ALMA Band 7, spanning ∼36 GHz from 275 to 317 GHz and representing an order of magnitude increase in sensitivity over previous single-dish surveys. We detect 14 molecular species (including isotopologues), with five species (C34S, 13CS, H2CS, DNC, and C2D) detected for the first time in protoplanetary disks. Significant differences are observed in the molecular inventories of MWC 480 and LkCa 15, and we discuss how these results may be interpreted in light of the different physical conditions of these two disk systems.

Keywords: Protoplanetary disks, Astrochemistry
A Search for Neutrino Point-source Populations in 7 yr of IceCube Data with Neutrino-count Statistics. The presence of a population of point sources in a data set modifies the underlying neutrino-count statistics from the Poisson distribution. This deviation can be exactly quantified using the non-Poissonian template fitting technique, and in this work we present the first application of this approach to the IceCube high-energy neutrino data set. Using this method, we search in 7 yr of IceCube data for point-source populations correlated with the disk of the Milky Way, the Fermi bubbles, the Schlegel, Finkbeiner, and Davis dust map, or with the isotropic extragalactic sky. No evidence for such a population is found in the data using this technique, and in the absence of a signal, we establish constraints on population models with source-count distribution functions that can be described by a power law with a single break. The derived limits can be interpreted in the context of many possible source classes. In order to enhance the flexibility of the results, we publish the full posterior from our analysis, which can be used to establish limits on specific population models that would contribute to the observed IceCube neutrino flux.

Keywords: Neutrino telescopes, Bayesian statistics, High energy astrophysics, Posterior distribution, Neutrino astronomy, Astrostatistics, Astrostatistics distributions
Accounting for Selection Bias Using Simulations: A General Method and an Application to Millimeter-wavelength Surveys. We have developed a new Bayesian method to correct the flux densities of astronomical sources. The hybrid method combines a simulated likelihood to model survey selection together with an analytic source-count-based prior. The simulated likelihood captures the effect of complicated selection methods, such as multi-frequency filtering or imposed restrictions on recovered sample properties (e.g., color cuts). Simulations are also able to capture unanticipated sources of uncertainty. In this way, the method enables a broader application of Bayesian techniques. Use of an analytic prior allows variation of assumed source count models without re-simulating the likelihood. We present the method along with a detailed description of an application to real survey data from the Atacama Cosmology Telescope.

Keywords: Astronomy data modeling, Radio source catalogs, Astronomical techniques, Submillimeter astronomy, Astronomical methods