Sazuna/UAT_keywords huggingface dataset:
Back to Quiescence: Postoutburst Evolution of the Pulsar J1119-6127 and Its Wind Nebula. We report on the analysis of a deep Chandra observation of the high-magnetic-field pulsar (PSR) J1119-6127 and its compact pulsar wind nebula (PWN) taken in 2019 October, three years after the source went into outburst. The 0.5-7 keV postoutburst (2019) spectrum of the pulsar is best described by a two-component blackbody plus power-law model with a temperature of 0.2 ± 0.1 keV, photon index Γ = 1.8 ± 0.4, and X-ray luminosity of ${1.9}_{-0.3}^{+0.3}\times $ 1033 erg s-1, consistent with its preburst quiescent phase. We find that the pulsar has gone back to quiescence. The compact nebula shows a jet-like morphology elongated in the north-south direction, similar to the preburst phase. The postoutburst PWN spectrum is best fit by an absorbed power law with a photon index Γ = 2.3 ± 0.5 and a flux of ${3.2}_{-0.2}^{+0.3}$ ×10-14 erg cm-2 s-1 (0.5-7 keV). The PWN spectrum shows evidence of spectral softening in the postoutburst phase, with the preburst photon index Γ = 1.2 ± 0.4 changing to Γ = 2.3 ± 0.5 and the preburst luminosity of ${1.5}_{-0.2}^{+0.3}$ × 1032 erg s-1 changing to ${2.7}_{-0.2}^{+0.3}$ × 1032 erg s-1 in the 0.5-7 keV band, suggesting magnetar outbursts can impact PWNe. The observed timescale for returning to quiescence, of just a few years, implies a rather fast cooling process and favors a scenario where J1119 is temporarily powered by magnetic energy following the magnetar outburst, in addition to its spin-down energy.

Keywords: Magnetars, Radio pulsars
Probing Polarization and the Role of Magnetic Fields in Cloud Destruction in the Keyhole Nebula. We present polarimetric observations of the Keyhole Nebula in the Carina Nebula Complex carried out using the Stratospheric Observatory for Infrared Astronomy. The Keyhole Nebula, located to the west of η Carinae, is believed to be disturbed by the stellar winds from the massive star. We observed the Keyhole Nebula at 89 μm wavelength with the HAWC+ instrument. The observations cover the entire Keyhole Nebula spanning 8' by 5' with central position R.A. = 10:44:43 and decl. = -59:38:04. The typical uncertainty of polarization measurement is less than 0.5% in the region with intensity above 5500 MJy sr-1. The polarization fraction has a mean value of 2.4% with a standard deviation of 1.6% in the region above this intensity, similar to values in other high-mass star-forming regions. The magnetic field orientation in the bar-shaped structure is similar to the large-scale magnetic field orientation. On the other hand, the magnetic field direction in the loop is not aligned with the large-scale magnetic fields but is tightly aligned with the loop itself. Analysis of the magnetic field angles and the gas turbulence suggests that the field strength is ~70 μG in the loop. A simple comparison of the magnetic field tension to the ram pressure of η Carinae's stellar wind suggests that the magnetic fields in the Keyhole Nebula are not strong enough to maintain the current structure against the impact of the stellar wind and that the role of the magnetic field in resisting stellar feedback in this region is limited.

Keywords: Polarimetry, Molecular clouds, Photodissociation regions, Far infrared astronomy
Future Constraints on the Reionization History and the Ionizing Sources from Gamma-Ray Burst Afterglows. We forecast the reionization history constraints, inferred from Lyα damping wing absorption features, for a future sample of ~20 z ≥ 6 gamma-ray burst (GRB) afterglows. We describe each afterglow spectrum by a three-parameter model. First, L characterizes the size of the ionized region (the "bubble size") around a GRB host halo. Second, ⟨xH I⟩ is the volume-averaged neutral fraction outside of the ionized bubble around the GRB, which is approximated as spatially uniform. Finally, NH I denotes the column density of a local damped Lyα absorber (DLA) associated with the GRB host galaxy. The size distribution of ionized regions is extracted from a numerical simulation of reionization and evolves strongly across the epoch of reionization (EoR). The model DLA column densities follow the empirical distribution determined from current GRB afterglow spectra. We use a Fisher matrix formalism to forecast the ⟨xH I(z)⟩ constraints that can be obtained from follow-up spectroscopy of afterglows with S/N = 20 per R = 3000 resolution element at the continuum. We find that the neutral fraction may be determined to better than 10%-15% (1σ) accuracy from this data across multiple independent redshift bins at z ~ 6-10, spanning much of the EoR, although the precision degrades somewhat near the end of reionization. A more futuristic survey with 80 GRB afterglows at z ≥ 6 can improve the precision here by a factor of 2 and extend measurements out to z ~ 14. We further discuss how these constraints may be combined with estimates of the escape fraction of ionizing photons derived from the DLA column density distribution toward GRBs extracted at slightly lower redshift, z ~ 5. This combination will help in testing whether we have an accurate census of the sources that reionized the universe.

Keywords: Early universe, Reionization
Iron and Nickel Isotopes in IID and IVB Iron Meteorites: Evidence for Admixture of an SN II Component and Implications for the Initial Abundance of <SUP>60</SUP>Fe. We measured Fe and Ni isotopes in 13 iron meteorites from magmatic groups IID and IVB. Resolvable deficits (≈-0.14) are observed in ε60Ni in both groups. Small deficits (≈-0.08) are also evident in ε56Fe but not in the most neutron-rich isotope of Fe (58Fe). Relative to terrestrial material, the observed εiFe values are consistent with the presence of a small excesses of material in the parent bodies of IID and IVB irons that was produced in a type II supernova. The ε60Ni and ε56Fe values are uncorrelated in both groups. This is consistent with a nucleosynthetic origin of the ε56Fe deficits, whereas the ε60Ni deficits are best explained as radiogenic in nature due to the former presence of live 60Fe (t1/2 = 2.62 Ma) in the early solar system. The 60Ni deficits correspond to 60Fe/56Fe ratios of ≈3 × 10-7 at the time of core formation on the IID and IVB parent bodies. These data, in conjunction with previously published 182Hf-182W core formation ages, are used to estimate a solar system initial 60Fe/56Fe = (6.4 ± 2.0) × 10-7 for the formation region of carbonaceous chondrites.

Keywords: Iron meteorites, Astrochemistry, Protoplanetary disks, Stellar nucleosynthesis, N-body simulations
Evolution of High-redshift Quasar Hosts and Promotion of Massive Black Hole Seed Formation. High-redshift luminous quasars powered by accreting supermassive black holes (SMBHs) with mass ≳109 M⊙ constrain their formation pathways. We investigate the formation of heavy seeds of SMBHs through gas collapse in the quasar host progenitors, using merger trees to trace the halo growth in highly biased, overdense regions of the universe. The progenitor halos are likely irradiated by intense H2-photodissociating radiation from nearby star-forming galaxies and heat the interior gas by successive mergers. The kinetic energy of the gas originating from mergers, as well as the baryonic streaming motion, prevents gas collapse and delays prior star formation. With a streaming velocity higher than the rms value, gas clouds in nearly all 104 realizations of merger trees enter the atomic-cooling stage and begin to collapse isothermally with T ≃ 8000 K via Lyα cooling. The fraction of trees that host isothermal gas collapse is 14% and increases with streaming velocity, while the rest form H2-cooled cores after short isothermal phases. If the collapsing gas is enriched to Zcrit ~ 2 × 10-3 Z⊙, requiring efficient metal mixing, this fraction could be reduced by additional cooling via metal fine-structure lines. In the massive collapsing gas, the accretion rate onto a newly born protostar ranges between 3 × 10-3 M⊙ yr-1 and 5 M⊙ yr-1, among which a large fraction exceeds the critical rate suppressing stellar radiative feedback. As a result, we expect a distribution of stellar mass (presumably BH mass) ranging from several hundred to above 105 M⊙, potentially forming massive BH binary mergers and yielding gravitational-wave events.

Keywords: Supermassive black holes, High-redshift galaxies, Quasars
Origin of Spectral Hardening of Secondary Cosmic-Ray Nuclei. We discuss the acceleration and escape of secondary cosmic-ray (CR) nuclei, such as lithium, beryllium, and boron, produced by spallation of primary CR nuclei like carbon, nitrogen, and oxygen accelerated at the shock in supernova remnants (SNRs) surrounded by the interstellar medium (ISM) or a circumstellar medium (CSM). We take into account the energy-dependent escape of CR particles from the SNR shocks, which is supported by gamma-ray observations of SNRs, to calculate the spectra of primary and secondary CR nuclei running away into the ambient medium. We find that if the SNR is surrounded by a CSM with a wind-like density distribution (i.e., nCSM ∝ r-2), the spectra of the escaping secondary nuclei are harder than those of the escaping primary nuclei, while if the SNR is surrounded by a uniform ISM, the spectra of the escaping secondaries are always softer than those of the escaping primaries. Using this result, we show that if there was a past supernova surrounded by a dense wind-like CSM (~2.5 × 10-3 M⊙ yr-1), which happened ~1.6 × 105 yr ago at a distance of ~1.6 kpc, we can simultaneously reproduce the spectral hardening of primary and secondary CRs above ~200 GV that have recently been reported by AMS-02.

Keywords: Cosmic ray astronomy, Cosmic ray sources, Cosmic rays
Characterization of HD 206893 B from Near- to Thermal-infrared. HD 206893 B is a brown-dwarf companion orbiting inside the debris disk of its host star. We detect the brown dwarf in the Ms band using the Keck/NIRC2 instrument and vortex coronagraph. We measure its magnitude to be ${Ms}={12.97}_{-0.11}^{0.10}$ . It is at an angular separation of 0"22 ± 0"03, and a position angle of 39.6° ± 5.4° east of north. Using this Ms-band measurement and the system age, we use three evolutionary models to estimate the mass to be 12-78 MJup. We analyze the atmospheric properties from 1-5 μm using a grid of simulated atmospheric models. We find that a sedimentation flux fsed value ~0.2 provides the best fit to the data, suggesting high vertically extended clouds. This may be indicative of high-altitude grains or a circumplanetary disk. Our model radii and luminosities for the companion find the best fits are ages of &lt;100 Myr and masses &lt;20 MJup, consistent with our mass estimate from the evolutionary models using the Ms-band data alone. We detect orbital motion of the brown dwarf around the host star in comparison to the discovery image and derive orbital parameters. Finally we analyze how the companion brown dwarf interacts with the debris disk by estimating the location of the chaotic zone around the brown dwarf using values derived from this study's estimated mass and orbital constraints. We find that the collisions within the debris belt are likely driven by secular perturbations from the brown dwarf, rather than self-stirring.

Keywords: Brown dwarfs, Coronagraphic imaging, Direct imaging, Astrometry, Debris disks, Exoplanet atmospheres
The Blue Supergiant Progenitor of the Supernova Imposter AT 2019krl. Extensive archival Hubble Space Telescope, Spitzer Space Telescope, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT 2019krl in M74, reveal a bright optical and mid-infrared progenitor star. While the optical peak of the event was missed, a peak was detected in the infrared with an absolute magnitude of M4.5 μm = -18.4 mag, leading us to infer a visual-wavelength peak absolute magnitude of -13.5 to -14.5. The pre-discovery light curve indicated no outbursts over the previous 16 yr. The colors, magnitudes, and inferred temperatures of the progenitor best match a 13-14 M☉ yellow or blue supergiant (BSG) if only foreground extinction is taken into account, or a hotter and more massive star if any additional local extinction is included. A pre-eruption spectrum of the star reveals strong Hα and [N II] emission with wings extending to ±2000 km s-1. The post-eruption spectrum is fairly flat and featureless with only Hα, Na I D, [Ca II], and the Ca II triplet in emission. As in many previous intermediate-luminosity transients, AT 2019krl shows remarkable observational similarities to luminous blue variable (LBV) giant eruptions, SN 2008S-like events, and massive-star mergers. However, the information about the pre-eruption star favors either a relatively unobscured BSG or a more extinguished LBV with M &gt; 20 M☉ likely viewed pole-on.

Keywords: Eruptive variable stars, Evolved stars, Massive stars, Luminous blue variable stars, Supergiant stars
The AGORA High-resolution Galaxy Simulations Comparison Project. III. Cosmological Zoom-in Simulation of a Milky Way-mass Halo. We present a suite of high-resolution cosmological zoom-in simulations to z = 4 of a 1012 M☉ halo at z = 0, obtained using seven contemporary astrophysical simulation codes (ART-I, ENZO, RAMSES, CHANGA, GADGET-3, GEAR, and GIZMO) widely used in the numerical galaxy formation community. The physics prescriptions for gas cooling and heating and star formation are the same as the ones used in our previous Assembling Galaxies of Resolved Anatomy (AGORA) disk comparison but now account for the effects of cosmological processes such as the expansion of the universe, intergalactic gas inflow, and the cosmic ultraviolet background radiation emitted by massive stars and quasars. In this work, we introduce the most careful comparison yet of galaxy formation simulations run by different code groups, together with a series of four calibration steps each of which is designed to reduce the number of tunable simulation parameters adopted in the final run. In the first two steps, we methodically calibrate the gas physics, such as cooling and heating, in simulations without star formation. In the third step, we seek agreement on the total stellar mass produced with the common star formation prescription used in the AGORA disk comparison, in stellar-feedback-free simulations. In the last calibration step, we activate stellar feedback, where each code group is asked to set the feedback prescription to as close to the most widely used one in its code community as possible, while aiming for convergence in the stellar mass at z = 4 to the values predicted by semiempirical models. After all the participating code groups successfully complete the calibration steps, we achieve a suite of cosmological simulations with similar mass assembly histories down to z = 4. With numerical accuracy that resolves the internal structure of a target halo (≲100 physical pc at z = 4), we find that the codes overall agree well with one another, e.g., in gas and stellar properties, but also show differences, e.g., in circumgalactic medium (CGM) properties. We argue that, if adequately tested in accordance with our proposed calibration steps and common parameters, high-resolution cosmological zoom-in simulations can have robust and reproducible results. New code groups are invited to join and enrich this comparison by generating equivalent models or to test the code's compatibility on their own, by adopting the common initial conditions, the common easy-to-implement physics package, and the proposed calibration steps. Further analyses of the zoom-in simulations presented here will be presented in forthcoming reports from the AGORA Collaboration, including studies of the CGM, simulations by additional codes, and results at lower redshift.

Keywords: Hydrodynamical simulations, Galaxy formation, Stellar feedback, Astronomical simulations
A New Broadening Technique of the Numerically Unresolved Solar Transition Region and Its Effect on the Spectroscopic Synthesis Using Coronal Approximation. The transition region is a thin layer of the solar atmosphere that controls the energy loss from the solar corona. Large numbers of grid points are required to resolve this thin transition region fully in numerical modeling. In this study, we propose a new numerical treatment, called LTRAC, which can be easily extended to the multidimensional domains. We have tested the proposed method using a one-dimensional hydrodynamic model of a coronal loop in an active region. The LTRAC method enables modeling of the transition region with a numerical grid size of 50-100 km, which is about 1000 times larger than the physically required value. We used the velocity differential emission measure to evaluate the possible effects on the optically thin emission. Lower-temperature emissions were better reproduced by the LTRAC method than by previous methods. Doppler shift and nonthermal width of the synthesized line emission agree with those from a high-resolution reference simulation within an error of several kilometers per second above the formation temperature of 105 K.

Keywords: Hydrodynamical simulations, Solar corona, Solar transition region
An Improved and Physically Motivated Scheme for Matching Galaxies with Dark Matter Halos. The simplest scheme for predicting real galaxy properties after performing a dark matter simulation is to rank order the real systems by stellar mass and the simulated systems by halo mass and then simply assume monotonicity-that the more massive halos host the more massive galaxies. This has had some success, but we study here if a better motivated and more accurate matching scheme is easily constructed by looking carefully at how well one could predict the simulated IllustrisTNG galaxy sample from its dark matter computations. We find that using the dark matter rotation curve peak velocity, vmax, for normal galaxies reduces the error of the prediction by 30% (18% for central galaxies and 60% for satellite systems)-following expectations from the physics of monolithic collapse. For massive systems with halo mass &gt;1012.5 M⊙ hierarchical merger driven formation is the better model and dark matter halo mass remains the best single metric. Using a new single variable that combines these effects, φ = vmax/ ${v}_{\max ,12.7}$ + Mpeak/(1012.7 M⊙) allows further improvement and reduces the error, as compared to ranking by dark matter mass at z = 0 by another 6% from vmax ranking. Two parameter fits-including environmental effects produce only minimal further impact.

Keywords: Galaxy dark matter halos, Galaxies
Radio Detection of PSR J1813-1749 in HESS J1813-178: The Most Scattered Pulsar Known. The 44.7 ms X-ray pulsar in the supernova remnant G12.82-0.02/HESS J1813-178 has the second highest spin-down luminosity of known pulsars in the Galaxy, with $\dot{E}=5.6\times {10}^{37}$ erg s-1. Using the Green Bank Telescope, we have detected radio pulsations from PSR J1813-1749 at 4.4-10.2 GHz. The pulse is highly scattered, with an exponential decay timescale τ longer than that of any other pulsar at these frequencies. A point source detected at this position by Dzib et al. in several observations with the Jansky Very Large Array can be attributed to the pulsed emission. The steep dependence of τ on observing frequency explains why all previous pulsation searches at lower frequencies failed (τ ≈ 0.25 s at 2 GHz). The large dispersion measure, DM = 1087 pc cm-3, indicates a distance of either 6.2 or 12 kpc according to two widely used models of the electron density distribution in the Galaxy. These disfavor a previously suggested association with a young stellar cluster at the closer distance of 4.8 kpc. The high X-ray measured column density of ≈1023 cm-2 also supports a large distance. If d ≈ 12 kpc, HESS J1813-178 would be one of the most luminous TeV sources in the Galaxy.

Keywords: Rotation powered pulsars, Galactic radio sources, Gamma-ray sources, Supernova remnants, Interstellar scattering, Radio pulsars
Anharmonic Vibrational Spectrum and Experimental Matrix Isolation Study of Thioformic Acid Conformers-Potential Candidates for Molecular Cloud and Solar System Observations?. Thioformic acid (TFA) is the sulfur analog of formic acid, the simplest organic acid. It has three analogs, HCOSH, HCSOH, and HCSSH, each of them having two rotational isomeric (rotameric) forms: trans and cis where the trans form is energetically more stable. In this article, we study computational energetics and anharmonic vibrational spectrum of TFA, including overtone and combination vibrations. We also studied experimental photoisomerization and photodecomposition channels of HCOSH molecules with different wavelengths. We suggest that TFA is a potential sulfur-containing candidate molecule for interstellar and planetary observations and discuss these in light of different radiation environments in space. More generally, we discuss that infrared radiation-driven photoisomerization reactions may be a common phenomenon in such environments and can affect the chemical reaction pathways of organic and other interstellar molecules.

Keywords: Molecular spectroscopy, Molecular clouds, Astrochemistry
Multiwavelength Evidence for a New Flare-mode Transitional Millisecond Pulsar. We report the discovery of a new low-mass X-ray binary near the center of the unassociated Fermi GeV γ-ray source 4FGL J0540.0-7552. The source shows the persistent presence of an optical accretion disk and exhibits extreme X-ray and optical variability. It also has an X-ray spectrum well-fit by a hard power law with Γ = 1.8 and a high ratio of X-ray to γ-ray flux. Together, these properties are consistent with the classification of the binary as a transitional millisecond pulsar (tMSP) in the subluminous disk state. Uniquely among the candidate tMSPs, 4FGL J0540.0-7552 shows consistent optical, X-ray, and γ-ray evidence for having undergone a state change, becoming substantially brighter in the optical and X-rays and fainter in GeV γ-rays sometime in mid-2013. In its current subluminous disk state, and like one other candidate tMSP in the Galactic field, 4FGL J0540.0-7552 appears to always be in an X-ray "flare mode," indicating that this could be common phenomenology for tMSPs.

Keywords: Millisecond pulsars
A Test of the Hadronic Origin of γ-Rays from Blazars with Follow-up up to a Month Later of IceCube Alerts with Imaging Air Cherenkov Telescopes. The sources of IceCube neutrinos are as yet unknown. The multimessenger observation of their emission in γ-rays can be a guide to their identification, as exemplified by the case of TXS 0506+056. We suggest a new method of searching for γ-rays with Imaging Air Cherenkov Telescopes from sources coinciding with possible astrophysical neutrinos. We propose that searches of γ-rays be extended from the current practice of only a few days to up to one month from a neutrino alert. We test this strategy on simulated sources modeled after the blazar TXS 0506+056, emitting neutrinos and γ-rays via photohadronic interactions: the γ-rays are subsequently reprocessed in the VHE range. Using MAGIC as a benchmark example, we show that current Cherenkov Telescopes should be able to detect γ-ray counterparts to neutrino alerts with a rate of approximately one per year. It has been proposed that the high-energy diffuse neutrino flux can be explained by ~5% of all blazars flaring in neutrinos once every 10 yr, with a neutrino luminosity similar to that of TXS 0506+056 during the 2014-2015 neutrino flare. The implementation of our strategy could lead, over a timescale of one or a few years, either to the detection of this subclass of blazars contributing to the diffuse neutrino flux or to a constraint on this model.

Keywords: Neutrino telescopes, Blazars, Neutrino astronomy, Gamma-ray telescopes, Gamma-ray astronomy, Gamma-ray transient sources