Sazuna/UAT_keywords huggingface dataset:
Minutes-delayed Jets from a Neutron Star Companion in Core-collapse Supernovae. This paper presents cases in which a neutron star (NS; or a black hole) companion to a type-Ib or type-Ic (stripped-envelope) core-collapse supernova (CCSN) accretes mass from the explosion ejecta and launches jets minutes to hours after explosion. The NS orbits at a pre-explosion radius of a ≃ 1-5 R⊙. When the ejecta velocity drops to ${v}_{\mathrm{ej}}\lesssim 1000\mbox{--}1500\,\mathrm{km}\,{{\rm{s}}}^{-1}$ , the ejecta gas that the NS accretes possesses sufficient specific angular momentum to form an accretion disk around the NS. The NS accretes a fraction of $({M}_{\mathrm{acc},{\rm{d}}}/{M}_{\mathrm{ej}})\approx 3\times {10}^{-5}\mbox{--}3\times {10}^{-4}$ of the ejecta mass through an accretion disk over a time period of ${t}_{{\rm{jets}}}\approx $ 10 minutes-few hr. If the jets carry about 10% of the accretion energy, then their total energy is a fraction of about 0.003-0.03 of the kinetic energy of the ejecta. The implications of these jets from an NS (or a black hole) companion to a CCSN are the shaping of the inner ejecta to have a bipolar morphology, energizing the light curve of the CCSN, and in some cases the possible enrichment of the inner ejecta with r-process elements.

Keywords: Neutron stars, Type Ib supernovae, Stellar jets, Compact binary stars, High mass x-ray binary stars, Supernovae, Common envelope binary stars
Exploring the Possibility of Identifying Hydride and Hydroxyl Cations of Noble Gas Species in the Crab Nebula Filament. The first identification of the argonium ion ( ${\mathrm{ArH}}^{+}$ ) toward the Crab Nebula supernova remnant was proclaimed by Herschel in the submillimeter and far-infrared domains. Very recently, the discovery of the hydro-helium cation ( ${\mathrm{HeH}}^{+}$ ) in the planetary nebula (NGC 7027) by SOFIA has been reported. The elemental abundance of neon is much higher than that of argon. However, the presence of neonium ions ( ${\mathrm{NeH}}^{+}$ ) is yet to be confirmed in space. Though the hydroxyl radicals (-OH) are very abundant in both neutral and cationic forms, hydroxyl cations of such noble gases (i.e., ArOH+, NeOH+, and HeOH+) are yet to be identified in space. Here, we employ a spectral synthesis code to examine the chemical evolution of the hydride and hydroxyl cations of the various isotopes of Ar, Ne, and He in the Crab Nebula filament and calculate their line emissivity and intrinsic line surface brightness. We successfully explain the observed surface brightness of two transitions of ArH+ (617 and 1234 GHz), one transition of OH+ (971 GHz), and one transition of H2 (2.12 μm). We also explain the observed surface brightness ratios between various molecular and atomic transitions. We find that our model reproduces the overall observed features when a hydrogen number density of ∼(104-106) cm-3 and a cosmic-ray ionization rate per H2 of ∼(10-11-10-10) s-1 are chosen. We discuss the possibility of detecting some hydride and hydroxyl cations in the Crab and diffuse cloud environment. Some transitions of these molecules are highlighted for future astronomical detection.

Keywords: Chemical abundances, Supernova remnants, Interstellar medium, Radiative transfer simulations, Diffuse interstellar clouds
On the Nature of the T Tauri Triple System. We present a multiwavelength analysis to reveal the nature of the enigmatic T Tauri triple star system. New optical and infrared measurements are coupled with archival X-ray, UV, and millimeter data sets to show the morphologies of disk material and outflow kinematics. A dark lane of obscuring material is seen in silhouette in several emission lines and in model-subtracted ALMA millimeter continuum dust residuals near the position of T Tau Sa+Sb, revealing the attenuating circumbinary ring around T Tau S. The flux variability of T Tau S is linked in part to the binary orbit; T Tau Sb brightens near orbital apastron as it emerges from behind circumbinary material. Outflow diagnostics confirm that T Tau N powers the blueshifted western outflow, and the T Tau S binary drives the northwest-southeastern flow. Analysis of the southern outflow shows periodic arcs ejected from the T Tau system. Correlation of these arc locations and tangential kinematics with the orbit timing suggests that launch of the last four southern outflow ejections is contemporaneous with, and perhaps triggered by, the T Tau Sa+Sb binary periastron passage. We present a geometry of the T Tau triple that has the southern components foreground to T Tau N, obscured by a circumbinary ring, with misaligned disks and interacting outflows. Particularly, a wind from T Tauri Sa that is perpendicular to its circumstellar disk might interact with the circumbinary material, which may explain conflicting high-contrast measurements of the system outflows in the literature. T Tauri is an important laboratory for understanding early dynamical processes in young multiple systems. We discuss the historical and future characteristics of the system in this context.

Keywords: Circumstellar disks, Stellar jets, Classical T Tauri stars
On the Detection Potential of Blazar Flares for Current Neutrino Telescopes. Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual high-energy neutrinos with blazar flares could be achieved via spatially and temporally coincident detections. In 2017, the track-like, extremely high-energy neutrino event IC 170922A was found to coincide with increased γ-ray emission from the blazar TXS 0506+056, leading to the identification of the most promising neutrino point-source candidate so far. We calculate the expected number of neutrino events that can be detected with IceCube, based on a broadband parameterization of bright short-term blazar flares that were observed in the first 6.5 yr of Fermi/Large Area Telescope observations. We find that the integrated keV-to-GeV fluence of most individual blazar flares is far too small to yield a substantial Poisson probability for the detection of one or more neutrinos with IceCube. We show that the sample of potentially detectable high-energy neutrinos from individual blazar flares is rather small. We further show that the blazars 3C 279 and PKS 1510-089 dominate the all-sky neutrino prediction from bright and short-term blazar flares. In the end, we discuss strategies to search for more significant associations in future data unblindings of IceCube and KM3NeT.

Keywords: Blazars, Neutrino astronomy, Gamma-ray astronomy, Active galactic nuclei
Solar Wind Turbulence Around Mars: Relation between the Energy Cascade Rate and the Proton Cyclotron Waves Activity. The first estimation of the incompressible energy cascade rate at magnetohydrodynamic (MHD) scales in the plasma upstream of the Martian bow shock is obtained, making use of magnetic field and plasma observations provided by Mars Atmosphere and Volatile EvolutioN (MAVEN) over 600 orbits. In particular, the energy cascade rate is computed for events with and without proton cyclotron wave (PCW) activity, for time intervals when MAVEN was in the solar wind with no magnetic connection to the bow shock. It is shown that the nonlinear cascade of energy at the MHD scales is slightly amplified when PCWs are present in the plasma, around the Martian perihelion. In addition, the analysis of the normalized cross helicity and residual energy for the turbulent fluctuations shows the presence of Alfvénic and non-Alfvénic fluctuations in a magnetic dominant regime for the majority of the cases.

Keywords: Interplanetary turbulence, Solar wind, Plasma physics
The Dynamics, Destruction, and Survival of Supernova-formed Dust Grains. Observations have demonstrated that supernovae efficiently produce dust. This is consistent with the hypothesis that supernovae and asymptotic giant branch stars are the primary producers of dust in the universe. However, there has been a longstanding question of how much of the dust detected in the interiors of young supernova remnants can escape into the interstellar medium. We present new hydrodynamical calculations of the evolution of dust grains that were formed in dense ejecta clumps within a Cas A-like remnant. We follow the dynamics of the grains as they decouple from the gas after their clump is hit by the reverse shock. They are subsequently subject to destruction by thermal and kinetic sputtering as they traverse the remnant. Grains that are large enough (∼0.25 μm for silicates and ∼0.1 μm for carbonaceous grains) escape into the interstellar medium while smaller grains get trapped and destroyed. However, grains that reach the interstellar medium still have high velocities, and are subject to further destruction as they are slowed down. We find that for initial grain size distributions that include large (∼0.25-0.5 μm) grains, 10%-20% of silicate grains can survive, while 30-50% of carbonaceous grains survive even when the initial size distribution cuts off at smaller (0.25 μm) sizes. For a 19 M⊙ star similar to the progenitor of Cas A, up to 0.1 M⊙ of dust can survive if the dust grains formed are large. Thus we show that supernovae under the right conditions can be significant sources of interstellar dust.

Keywords: Interstellar dust, Supernova remnants, Core-collapse supernovae, Interstellar dust processes
The Submillimeter Active Region Excess Brightness Temperature during Solar Cycles 23 and 24. We report the temporal evolution of the excess brightness temperature ΔTb above solar active regions (ARs) observed with the Solar Submillimeter Telescope (SST) at 212 (λ = 1.4 mm) and 405 GHz (λ = 0.7 mm) during Cycles 23 and 24. Comparison with the sunspot number (SSN) yields a Pearson's correlation coefficient R = 0.88 and 0.74 for 212 and 405 GHz, respectively. Moreover, when only Cycle 24 is taken into account the correlation coefficients go to 0.93 and 0.81 for each frequency. We derive the spectral index α between SST frequencies and find a slight anticorrelation with the SSN (R = -0.25); however, since the amplitude of the variation is lower than the standard deviation we cannot draw a definite conclusion. Indeed, α remains almost constant within the uncertainties with a median value of ≈0 characteristic of an optically thick thermal source. Since the origin of the AR submillimeter radiation is thermal continuum produced at chromospheric heights, the strong correlation between ΔTb and the magnetic cycle evolution could be related to the available free magnetic energy to be released in reconnection events.

Keywords: Active solar chromosphere
A Spectroscopic Survey of Lyα Emitters at z ≈ 3.1 over ∼1.2 Deg<SUP>2</SUP>. We present a spectroscopic survey of Lyα emitters (LAEs) at z ≈ 3.1 in the Subaru XMM-Newton Deep Survey Field. This field has deep imaging data in a series of broad and narrow bands, including two adjacent narrow bands NB497 and NB503 that have allowed us to efficiently select LAE candidates at z ≈ 3.1. Using spectroscopic observations on MMT Hectospec and Magellan M2FS, we obtained a sample of 166 LAEs at z ≈ 3.1 over an effective area of ∼1.2 deg2, including 16 previously known LAEs. This is so far the largest (spectroscopically confirmed) sample of LAEs at this redshift. We make use of the secure redshifts and multiband data to measure spectral properties such as Lyα luminosity and rest-frame UV slope. We derive a robust Lyα luminosity function (LF) that spans a luminosity range from ∼1042.0 to &gt;1043.5 erg s-1. Significant overdense and underdense regions are detected in our sample, but the area coverage is wide enough to largely suppress the effect from such cosmic variance. Our Lyα LF is generally consistent with those from previous studies at z ∼ 3.1. At the brightest end of the LF, there is a tentative detection of a density excess that is not well described by the Schechter function. The comparison with the LFs at other redshifts suggests that the Lyα LF does not show significant evolution at 2 &lt; z &lt; 5. Finally, we build the composite spectra of the LAEs and detect the N V λ1239 and C IV λλ1548,1551 doublet emission lines at significance of ∼4σ, suggesting very hard radiation fields in (some of) these LAEs.

Keywords: Lyman-alpha galaxies, High-redshift galaxies, Galaxy properties
Mitigating Shear-dependent Object Detection Biases with Metacalibration. METACALIBRATION is a new technique for measuring weak gravitational lensing shear that is unbiased for isolated galaxy images. In this work we test METACALIBRATION with overlapping, or "blended" galaxy images. Using standard METACALIBRATION, we find a few percent shear measurement bias for galaxy densities relevant for current surveys, and that this bias increases with increasing galaxy number density. We show that this bias is not due to blending itself, but rather to shear-dependent object detection. If object detection is shear-independent, no deblending of images is needed, in principle. We demonstrate that detection biases are accurately removed when including object detection in the METACALIBRATION process, a technique we call METADETECTION. This process involves applying an artificial shear to images of small regions of sky and performing detection on the sheared images, as well as measurements that are used to calculate a shear response. We demonstrate that the method can accurately recover weak shear signals even in highly blended scenes. In the METACALIBRATION process, the space between objects is sheared coherently, which does not perfectly match the real universe in which some, but not all, galaxy images are sheared coherently. We find that even for the worst case scenario, in which the space between objects is completely unsheared, the resulting shear bias is at most a few tenths of a percent for future surveys. We discuss additional technical challenges that must be met in order to implement METADETECTION for real surveys.

Keywords: Weak gravitational lensing
Direct Evidence of Two-component Ejecta in Supernova 2016gkg from Nebular Spectroscopy. Spectral observations of the type-IIb supernova (SN) 2016gkg at 300-800 days are reported. The spectra show nebular characteristics, revealing emission from the progenitor star's metal-rich core and providing clues to the kinematics and physical conditions of the explosion. The nebular spectra are dominated by emission lines of [O I] λλ6300, 6364 and [Ca II] λλ7292, 7324. Other notable, albeit weaker, emission lines include Mg I] λ4571, [Fe II] λ7155, O I λ7774, Ca II triplet, and a broad, boxy feature at the location of Hα. Unlike in other stripped-envelope SNe, the [O I] doublet is clearly resolved due to the presence of strong narrow components. The doublet shows an unprecedented emission line profile consisting of at least three components for each [O I]λ6300, 6364 line: a broad component (width ∼2000 km s-1), and a pair of narrow blue and red components (width ∼300 km s-1) mirrored against the rest velocity. The narrow component appears also in other lines, and is conspicuous in [O I]. This indicates the presence of multiple distinct kinematic components of material at low and high velocities. The low-velocity components are likely to be produced by a dense, slow-moving emitting region near the center, while the broad components are emitted over a larger volume. These observations suggest an asymmetric explosion, supporting the idea of two-component ejecta that influence the resulting late-time spectra and light curves. SN 2016gkg thus presents striking evidence for significant asymmetry in a standard-energy SN explosion. The presence of material at low velocity, which is not predicted in 1D simulations, emphasizes the importance of multidimensional explosion modeling of SNe. * Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 0100.D-0341; the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea), programs GS-2017B-Q-65, GS-2018B-FT-107 (Fast Turnaround); and the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, program S17B-162S.

Keywords: Core-collapse supernovae
ALMA Observations of HCO<SUP>+</SUP> and HCN Emission in the Massive Star-forming Region N55 of the Large Magellanic Cloud. We present the results of high spatial resolution HCO+(1-0) and HCN(1-0) observations of the N55 south region (N55-S) in the Large Magellanic Cloud (LMC), obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). N55-S is a relatively less extreme star-forming region of the LMC characterized by a low radiation field. We carried out a detailed analysis of the molecular emission to investigate the relation between dense molecular clumps and star formation in the quiescent environment of N55-S. We detect 10 molecular clumps with significant HCO+(1-0) emission and 8 with significant HCN(1-0) emission, and estimate the molecular clump masses by virial and local thermodynamic equilibrium analysis. All identified young stellar objects (YSOs) in N55-S are found to be near the HCO+ and HCN emission peaks showing the association of these clumps with recent star formation. The molecular clumps that have associated YSOs show relatively larger line widths and masses than those without YSOs. We compare the clump properties of N55-S with those of other giant molecular clouds (GMCs) in the LMC and find that N55-S clumps possess similar size but relatively lower line width and larger HCN/HCO+(1-0) flux ratio. These results can be attributed to the low radiation field in N55-S resulted by relatively low star formation activity compared to other active star-forming regions like 30 Doradus-10 and N159. The dense gas fraction of N55-S is ∼0.025, lower compared to other GMCs of the LMC supporting the low star formation efficiency of this region.

Keywords: Interstellar molecules, Large Magellanic Cloud, Giant molecular clouds, Young stellar objects, Star formation
The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. III. Substructures in Protostellar Disks. The prevalence of substructures in ∼1-10 Myr old protoplanetary disks, which are often linked to planet formation, has raised the question of how early such features form and, as a corollary, how early planet formation begins. Here we present observations of seven protostellar disks (aged ∼ 0.1-1 Myr) from the Very Large Array/Atacama Large Millimeter/Submillimeter Array Nascent Disk and Multiplicity Survey of Orion Protostars (VANDAM: Orion) that show clear substructures, thereby demonstrating that these features can form early in the lifetimes of disks. We use simple analytic models as well as detailed radiative transfer modeling to characterize their structure. In particular we show that at least four of the sources have relatively massive envelopes, indicating that they are particularly young, likely the youngest disks with substructures known to date. Several of these disks also have emission from an inner disk that is offset from the center of the ring structure. Given the size of the cleared-out regions of the disk, it is unclear, however, whether these features are related to planet formation, or rather if they are signposts of close-separation binary formation at early times.

Keywords: Protostars, Star formation, Protoplanetary disks
Oblique Tearing Mode Instability: Guide Field and Hall Effect. The tearing mode instability is one important mechanism that may explain the triggering of fast magnetic reconnection in astrophysical plasmas, such as the solar corona and the Earth's magnetosphere. In this paper, the linear stability analysis of the tearing mode is carried out for a current sheet in the presence of a guide field, including the Hall effect. We show that the presence of a strong guide field does not modify the most unstable mode in the 2D wavevector space orthogonal to the current gradient direction, which remains the fastest-growing parallel mode. With the Hall effect, the inclusion of a guide field turns the nondispersive propagation along the guide field direction to a dispersive one. The oblique modes have a wavelike structure along the normal direction of the current sheet and a strong guide field suppresses this structure while making the eigenfunctions asymmetric.

Keywords: Magnetohydrodynamics, Solar magnetic reconnection, Plasma physics
Empirical Test for Relativistic Kinetic Theories Based on the Sunyaev-Zel'dovich Effect. We propose a new method to determine the electron velocity (EV) distribution function in the intracluster gas (ICG) in clusters of galaxies based on the frequency dependence of the Sunyaev-Zel'dovich (SZ) effect. It is generally accepted that the relativistic equilibrium EV distribution is the one suggested by Jüttner. However, there is an ongoing debate on the foundation of relativistic kinetic theory, and other distributions have also been proposed. The mildly relativistic ICG provides a unique laboratory to test relativistic kinetic theories. We carried out Monte Carlo simulations to generate SZ signal from a single-temperature gas assuming the Jüttner EV distribution assuming a few percent errors. We fitted SZ models based on nonrelativistic Maxwellian, and its two relativistic generalizations, the Jüttner and modified Jüttner distributions. We found that a 1% error in the SZ signal is sufficient to distinguish between these distributions with high significance based on their different best-fit temperatures. However, in any line of sight (LOS) in a cluster, the ICG contains a range of temperatures. Using our N-body/hydrodynamical simulation of a merging galaxy cluster and assuming a 1% error in the SZ measurements in an LOS through a bow shock, we find that it is possible to distinguish between Jüttner and modified Jüttner distributions with high significance. Our results suggest that deriving ICG temperatures from fitting to SZ data assuming different EV distribution functions and comparing them to the temperature in the same cluster obtained using other observations would enable us to distinguish between the different distributions.

Keywords: Galaxy clusters, Sunyaev-Zeldovich effect
The Massive and Distant Clusters of WISE Survey. X. Initial Results from a Sunyaev-Zeldovich Effect Study of Massive Galaxy Clusters at z &gt; 1 Using MUSTANG2 on the GBT. The properties of galaxy clusters as a function of redshift can be utilized as an important cosmological tool. We present initial results from a program of follow-up observations of the Sunyaev-Zeldovich effect (SZE) in high-redshift galaxy clusters detected by the Massive and Distant Clusters of WISE Survey (MaDCoWS) which uses infrared data from the Wide-field Infrared Survey (WISE) instrument. Using typical on-source integration times of 3-4 hr per cluster, MUSTANG2 on the Green Bank Telescope was able to measure strong detections of SZE decrements and statistically significant masses on 14 out of 16 targets. On the remaining two, weaker (3.7σ) detections of the SZE signal and strong upper limits on the masses were obtained. In this paper we present masses and pressure profiles of each target and outline the data analysis used to recover these quantities. Of the clusters with strong detections, three show significantly flatter pressure profiles while, from the MUSTANG2 data, five others show signs of disruption at their cores. However, outside of the cores of the clusters, we were unable to detect significant amounts of asymmetry. Finally, there are indications that the relationship between optical richness used by MaDCoWS and SZE-inferred mass may be significantly flatter than indicated in previous studies.

Keywords: Sunyaev-Zeldovich effect, High-redshift galaxy clusters