Sazuna/UAT_keywords huggingface dataset:
Distinct Thermal Emission from GRB 190109A. The gamma-ray bursts (GRBs) with distinct thermal components are rarely detected, especially in cases with thermal components throughout the prompt phase. Recently, Fermi/GBM, Swift/BAT, and Swift/XRT detected the special long-duration GRB 190109A, which has four pulses in the prompt gamma-ray emission, i.e, Pulse I (-4 to 20 s), Pulse II (20-50 s), Pulse III (50-90 s), and Pulse IV (90-120 s). GRB 190109A exhibits a very hard low-energy index (α ~ 1) in the Band function relative to the typical GRBs (α ~ - 1). In the whole burst prompt emission, we find distinct thermal emissions in the time-resolved spectra throughout four pulses. The blackbody (BB) temperature kT varies from 24.7 to 8.2 keV for Pulse I to Pulse IV. We also obtain the relation of F ∝ kT -0.40 for the early phase (Pulse I) and F ∝ kT 3.33±0.76 for the late phase (Pulses II-IV), respectively. The significant deviation of the kT - F relation in the early epochs from that in the late epochs likely suggests that the BB spectra origin of the early phase (Pulse I) may have disparate physical processes from those of the late phase (Pulses II-IV). For instance, it may be the transition from cocoon surroundings by a jet to the photosphere of the matter-dominated jet. A jet break is found in the late X-ray afterglow, which is in keeping with the standard external shock afterglow model in the interstellar medium circumburst.

Keywords: Gamma-ray bursts
On the Effect of the Large Magellanic Cloud on the Orbital Poles of Milky Way Satellite Galaxies. The reflex motion and distortion of the Milky Way (MW) halo caused by the infall of a massive Large Magellanic Cloud (LMC) has been demonstrated to result in an excess of orbital poles of dark matter halo particles toward the LMC orbital pole. This was suggested to help explain the observed preference of MW satellite galaxies to coorbit along the Vast Polar Structure (VPOS). We test this idea by correcting the positions and velocities of the MW satellites for the Galactocentric-distance-dependent shifts inferred from a LMC-infall simulation. While this should substantially reduce the observed clustering of orbital poles if it were mainly caused by the LMC, we instead find that the strong clustering remains preserved. We confirm the initial study's main result with our simulation of an MW-LMC-like interaction, and use it to identify two reasons why this scenario is unable to explain the VPOS: (1) the orbital pole density enhancement in our simulation is very mild (~10% within 50-250 kpc) compared to the observed enhancement (~220%-300%), and (2) it is very sensitive to the specific angular momenta (AM) of the simulation particles, with the higher-AM particles being affected the least. Particles in simulated dark matter halos tend to follow more radial orbits (lower AM), so their orbital poles are more easily affected by small offsets in position and velocity caused by a LMC infall than objects with more tangential velocity (higher AM), such as the observed dwarf galaxies surrounding the MW. The origin of the VPOS thus remains unexplained.

Keywords: Milky Way dark matter halo, Orbits, Dwarf galaxies, Milky Way dynamics, Dark matter
Connecting Primordial Star-forming Regions and Second-generation Star Formation in the Phoenix Simulations. We introduce the Phoenix Simulations, a suite of highly resolved cosmological simulations featuring hydrodynamics, primordial gas chemistry, primordial and enriched star formation and feedback, UV radiative transfer, and saved outputs with Δt = 200 kyr. We observe 73,523 individual primordial stars within 3313 distinct regions forming 2110 second-generation enriched star clusters by z ≥ 12 within a combined 177.25 Mpc3 volume across three simulations. The regions that lead to enriched star formation can contain ≳150 primordial stars, with 80% of regions having experienced combinations of primordial Type II, hypernovae, and/or pair-instability supernovae. Primordial supernovae enriched 0.8% of the volume, with 2% of enriched gas enriched by later-generation stars. We determine the extent of a primordial stellar region by its metal-rich or ionized hydrogen surrounding cloud; the metal-rich and ionized regions have time-dependent average radii r ≲ 3 kpc. 7 and 17% of regions have r &gt; 7 kpc for metal-rich and ionized radii, respectively. We find that the metallicity distribution function of second-generation stars overlaps that of subsequent Population II star formation, spanning metal-deficient (~7.94 × 10-8 Z ⊙) to supersolar (~3.71 Z ⊙), and that 30.5% of second-generation stars have Z &gt; 10-2 Z ⊙. We find that the metallicity of second-generation stars depends on progenitor configuration, with metals from pair-instability supernovae contributing to the most metal-rich clusters; these clusters form promptly after the supernova event. Finally, we create an interpretable regression model to predict the radius of the metal-rich influence of Population III star systems within the first 7-18 Myr after the first Population III stars form in the region.

Keywords: Population II stars, Star forming regions, Population III stars, Primordial galaxies
Unraveling the Innermost Jet Structure of OJ 287 with the First GMVA + ALMA Observations. We present the first very long baseline interferometric (VLBI) observations of the blazar OJ 287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on 2017 April 2. The participation of phased ALMA has not only improved the GMVA north-south resolution by a factor of ~3, but has also enabled fringe detections with signal-to-noise ratios up to 300 at baselines longer than 2 Gλ. The high sensitivity has motivated us to image the data with newly developed regularized maximum likelihood imaging methods, revealing the innermost jet structure with unprecedentedly high angular resolution. Our images reveal a compact and twisted jet extending along the northwest direction, with two bends within the inner 200 μas, resembling a precessing jet in projection. The component at the southeastern end shows a compact morphology and high brightness temperature, and is identified as the VLBI core. An extended jet feature that lies at ~200 μas northwest of the core shows a conical shape, in both total and linearly polarized intensity, and a bimodal distribution of the linear polarization electric vector position angle. We discuss the nature of this feature by comparing our observations with models and simulations of oblique and recollimation shocks with various magnetic field configurations. Our high-fidelity images also enabled us to search for possible jet features from the secondary supermassive black hole (SMBH) and test the SMBH binary hypothesis proposed for this source.

Keywords: AGN host galaxies, Supermassive black holes, Jets, Radio jets, Very long baseline interferometry, Radio continuum emission
The Effect of the Fluctuating Interplanetary Magnetic Field on the Cosmic Ray Intensity Profile of the Ground-level Enhancement (GLE) Events. We numerically integrate the equations of motion of a large number of GeV protons, released impulsively near the Sun, in order to study their time-intensity behavior at the location of an observer at 1 au. This is relevant to the interpretation of Ground Level Enhancements (GLEs) detected by neutron monitors on Earth. Generally, the observed time-intensity profiles reveal a single sharp rise, followed by slow decay. However, in the 1989 October 22 GLE event, there was an initial sharp spike followed by a secondary smaller spike in the particle intensity. We consider whether the propagation of the high-energy protons in a large-scale turbulent interplanetary magnetic field (IMF) can lead to this unusual time-intensity profile. The IMF model includes large-scale magnetic turbulence and a heliospheric current sheet. Ad-hoc scattering is used to mimic the effect of smaller-scale fluctuations resulting in pitch-angle scattering. Proton fluxes as a function of time and location for an observer are determined for various turbulence parameters, IMF polarities, and the size of the particle source near the Sun. We find that the fluctuating IMF leads to considerable variation in the arrival location of the particles crossing 1 au, and the time-intensity profile depends significantly on the observer's location and can have multiple peaks. An alternate explanation for the unusual structure in the 1989 October 22 GLE event is provided. Our findings show that the large-scale turbulent IMF enhances the access of the high-energy protons to the HCS at the early time of the event, which leads to efficient cross-field transport.

Keywords: Solar flares, Solar energetic particles, Interplanetary turbulence, Solar coronal mass ejection shocks, Interplanetary magnetic fields, Solar coronal mass ejections
PSP/WISPR Observations of Dust Density Depletion near the Sun. II. New Insights from within the Depletion Zone. Visible light observations from the Wide-field Imager for Solar PRobe (WISPR) aboard the Parker Solar Probe (PSP) mission offer a unique opportunity to study the dust environment near the Sun. The existence of a dust-free zone (DFZ) around stars was postulated almost a century ago. Despite numerous attempts to detect it from as close as 0.3 au, observational evidence of a circumsolar DFZ has remained elusive. Analysis of WISPR images obtained from heliocentric distances between 13.3-53.7 R ⊙ over multiple PSP orbits shows a gradually decreasing brightness gradient along the symmetry axis of the F-corona for coronal heights between 19 and 9 R ⊙. Below 9 R ⊙, the gradient reverses its trend, approaching the radial dependence exhibited at heights above 19 R ⊙. After taking into account the effects of both the electron corona background and the nonresolved starlight, the WISPR observations down to 4 R ⊙ are consistent with forward-modeling simulations of the F-corona brightness within [-6, 5]% if a circumsolar region of depleted dust density between 19 and 5 R ⊙ enclosing a DFZ is considered. In addition, we show, for the first time, that the F-corona brightness inward of about 15 R ⊙ depends on the observer's location for observing distances below 35 R ⊙.

Keywords: Circumstellar dust, Solar F corona
Long Dark Gaps in the Lyβ Forest at z &lt; 6: Evidence of Ultra-late Reionization from XQR-30 Spectra. We present a new investigation of the intergalactic medium near reionization using dark gaps in the Lyβ forest. With its lower optical depth, Lyβ offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Lyα line. We identify dark gaps in the Lyβ forest using spectra of 42 QSOs at z em &gt; 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10 h −1 Mpc at z ≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Lyα forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at z &lt; 6 due to a late end to reionization. Of particular interest is a very long (L = 28 h −1 Mpc) and dark (τ eff ≳ 6) gap persisting down to z ≃ 5.5 in the Lyβ forest of the z = 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of &lt;x H I&gt; ≳ 5% by z = 5.6. Finally, we infer constraints on &lt;x H I&gt; over 5.5 ≲ z ≲ 6.0 based on the observed Lyβ dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find &lt;x H I&gt; ≤ 0.05, 0.17, and 0.29 at z ≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later than z = 6.

Keywords: Reionization, High-redshift galaxies, Quasar absorption line spectroscopy, Intergalactic medium
ALMA Lensing Cluster Survey: ALMA-Herschel Joint Study of Lensed Dusty Star-forming Galaxies across z ≃ 0.5 - 6. We present an ALMA-Herschel joint analysis of sources detected by the ALMA Lensing Cluster Survey (ALCS) at 1.15 mm. Herschel/PACS and SPIRE data at 100-500 μm are deblended for 180 ALMA sources in 33 lensing cluster fields that are detected either securely (141 sources; in our main sample) or tentatively at S/N ≥ 4 with cross-matched HST/Spitzer counterparts, down to a delensed 1.15 mm flux density of ~0.02 mJy. We performed far-infrared spectral energy distribution modeling and derived the physical properties of dusty star formation for 125 sources (109 independently) that are detected at &gt;2σ in at least one Herschel band. A total of 27 secure ALCS sources are not detected in any Herschel bands, including 17 optical/near-IR-dark sources that likely reside at z = 4.2 ± 1.2. The 16th, 50th, and 84th percentiles of the redshift distribution are 1.15, 2.08, and 3.59, respectively, for ALCS sources in the main sample, suggesting an increasing fraction of z ≃ 1 - 2 galaxies among fainter millimeter sources (f 1150 ~ 0.1 mJy). With a median lensing magnification factor of $\mu ={2.6}_{-0.8}^{+2.6}$ , ALCS sources in the main sample exhibit a median intrinsic star formation rate of ${94}_{-54}^{+84}$ M ⊙ yr-1, lower than that of conventional submillimeter galaxies at similar redshifts by a factor of ~3. Our study suggests weak or no redshift evolution of dust temperature with L IR &lt; 1012 L ⊙ galaxies within our sample at z ≃ 0 - 2. At L IR &gt; 1012 L ⊙, the dust temperatures show no evolution across z ≃ 1-4 while being lower than those in the local universe. For the highest-redshift source in our sample (z = 6.07), we can rule out an extreme dust temperature (&gt;80 K) that was reported for MACS0416 Y1 at z = 8.31.

Keywords: Gravitational lensing, Galaxy evolution, Ultraluminous infrared galaxies, High-redshift galaxies, Luminous infrared galaxies
Hiding Planets Near and Far: The Parameter Space of Hidden Companions for Known Planetary Systems. Recent ground- and space-based observations show that stars with multiple planets are common in the Galaxy. Most of these observational methods are biased toward detecting large planets near to their host stars. Because of these observational biases, these systems can hide small, close-in planets or far-orbiting (big or small) companions. These planets can still exert dynamical influence on known planets and have such influence exerted on them in turn. In certain configurations, this influence can destabilize the system; in others, the star's gravitational influence can instead further stabilize the system. For example, in systems with planets close to the host star, effects arising from general relativity can help to stabilize the configuration. We derive criteria for hidden planets orbiting both beyond and within known planets that quantify how strongly general relativistic effects can stabilize systems that would otherwise be unstable. As a proof of concept, we investigate the several planets in a system based on Kepler-56 and show that the outermost planet will not disrupt the system even at high eccentricities, and we show that an Earth-radius planet could be stable within this system if it orbits below 0.08 au. Furthermore, we provide specific predictions to known observed systems by constraining the parameter space of possible hidden planets.

Keywords: Exoplanet dynamics, General relativity, Star-planet interactions, Planetary dynamics, Dynamical evolution
A Gap at 1 au in the Disk of DI Cha A Revealed by Infrared Interferometry. DI Cha A is K0-type pre-main-sequence star, the brightest component of a quadruple stellar system. Here we report on a detailed study of this star based on archival VLTI/MIDI and VLTI/PIONIER infrared interferometric observations, as well as optical-infrared photometric monitoring from ground-based and space-born instruments. We determined the structure of the circumstellar disk by fitting simultaneously the interferometric visibilities and the spectral energy distribution, using both analytical models and the radiative transfer code RADMC-3D. The modeling revealed that the radial density distribution of the disk appears to have a gap between 0.21 and 3.0 au. The inner ring, whose inner size coincides with the sublimation radius, is devoid of small, submicrometer-sized dust grains. The inner edge of the outer disk features a puffed-up rim, typically seen in intermediate-mass stars. Grain growth, although less progressed, was also detected in the outer disk. The inner ring is variable at mid-infrared wavelengths on both daily and annual timescales, while the star stays remarkably constant in the optical, pointing to geometrical or accretion changes in the disk as possible explanations for the flux variations. *Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 077.C-0662, 079.C-0101, and 081.C-0020

Keywords: Astronomy data modeling, T Tauri stars, Pre-main sequence stars, Protoplanetary disks, Interferometry
GeV Signatures of Short Gamma-Ray Bursts in Active Galactic Nuclei. The joint detection of gravitational waves and the gamma-ray counterpart of a binary neutron star merger event, GW170817, unambiguously validates the connection between short gamma-ray bursts and compact binary object (CBO) mergers. We focus on a special scenario where short gamma-ray bursts produced by CBO mergers are embedded in disks of active galactic nuclei (AGNs), and we investigate the γ-ray emission produced in the internal dissipation region via synchrotron, synchrotron self-Compton, and external inverse Compton (EIC) processes. In this scenario, isotropic thermal photons from the AGN disks contribute to the EIC component. We show that a low-density cavity can be formed in the migration traps, leading to the embedded mergers producing successful GRB jets. We find that the EIC component would dominate the GeV emission for typical CBO mergers with an isotropic-equivalent luminosity of L  j,iso = 1048.5 erg s-1 that are located close to the central supermassive black hole. Considering a long-lasting jet of duration T dur ~ 102-103 s, we find that the future Cherenkov Telescope Array (CTA) will be able to detect its 25-100 GeV emission out to a redshift z = 1.0. In the optimistic case, it is possible to detect the on-axis extended emission simultaneously with GWs within one decade using MAGIC, H.E.S.S., VERITAS, CTA, and LHAASO-WCDA. Early diagnosis of prompt emissions with Fermi-GBM and HAWC can provide valuable directional information for the follow-up observations.

Keywords: Non-thermal radiation sources, Gamma-ray bursts, Active galactic nuclei, Compact binary stars
Searching for Broadband Pulsed Beacons from 1883 Stars Using Neural Networks. The search for extraterrestrial intelligence at radio frequencies has largely been focused on continuous-wave narrowband signals. We demonstrate that broadband pulsed beacons are energetically efficient compared to narrowband beacons over longer operational timescales. Here, we report the first extensive survey searching for such broadband pulsed beacons toward 1883 stars as a part of the Breakthrough Listen's search for advanced intelligent life. We conducted 233 hr of deep observations across 4-8 GHz using the Robert C. Byrd Green Bank Telescope and searched for three different classes of signals with artificial (or negative) dispersion. We report a detailed search-leveraging a convolutional neural network classifier on high-performance GPUs-deployed for the very first time in a large-scale search for signals from extraterrestrial intelligence. Due to the absence of any signal-of-interest from our survey, we place a constraint on the existence of broadband pulsed beacons in our solar neighborhood: ≲1 in 1000 stars have transmitter power densities ≳105 W Hz-1 repeating ≤500 s at these frequencies.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Radio transient sources
Depletion of Moderately Volatile Elements by Open-system Loss in the Early Solar Nebula. Rocky bodies of the inner solar system display a systematic depletion of "moderately volatile elements" (MVEs) that correlates with the expected condensation temperature of their likely host materials under protoplanetary nebula conditions. In this paper, we present and test a new hypothesis in which open-system loss processes irreversibly remove vaporized MVEs from high nebula altitudes, leaving behind the more refractory solids residing much closer to the midplane. The MVEs irreversibly lost from the nebula through these open-system loss processes are then simply unavailable for condensation onto planetesimals forming even much later, after the nebula has cooled, overcoming a critical difficulty encountered by previous models of this type. We model open-system loss processes operating at high nebula altitudes, such as resulting from disk winds flowing out of the system entirely, or layered accretion directly onto the young Sun. We find that mass-loss rates higher than those found in typical T-Tauri disk winds, lasting short periods of time, are most satisfactory, pointing to multiple intense early outburst stages. Using our global nebula model, incorporating realistic particle growth and inward drift for solids, we constrain how much the MVE-depletion signature in the inner region is diluted by the drift of undepleted material from the outer nebula. We also find that a significant irreversible loss of the common rock-forming elements (Fe, Mg, Si) can occur, leading to a new explanation of another long-standing puzzle of the apparent "enhancement" in the relative abundance of highly refractory elements in chondrites.

Keywords: Solar system formation, Chondrites, Meteorite composition, Planetesimals, Meteorites
The Cooling of the Central Compact Object in Cas A from 2006 to 2020. We report on the study of six Chandra observations (four epochs) of the Central Compact Object (CCO) in the Cassiopeia A supernova remnant with the ACIS instrument in the subarray mode. This mode minimizes spectrum-distorting instrumental effects such as pileup. The data were taken over a time span of ~14 yr. If a non-magnetic carbon atmosphere is assumed for this youngest known CCO, then the temperature change is constrained to be $\dot{T}=-2900\pm 600$ K yr-1 or $\dot{T}=-4500\pm 800$ K yr-1 (1σ uncertainties) for constant or varying absorbing hydrogen column density. These values correspond to cooling rates of -1.5% ± 0.3% per 10 yr and -2.3% ± 0.4% per 10 yr, respectively. We discuss an apparent increase in the cooling rate in the last five years and the variations of the inferred absorbing hydrogen column densities between epochs. Considered together, these changes could indicate systematic effects such as caused by, e.g., an imperfect calibration of the increasing contamination of the ACIS filter.

Keywords: Neutron stars