Sazuna/UAT_keywords huggingface dataset:
Spin Doctors: How to Diagnose a Hierarchical Merger Origin. Gravitational-wave observations provide the unique opportunity of studying black hole formation channels and histories—but only if we can identify their origin. One such formation mechanism is the dynamical synthesis of black hole binaries in dense stellar systems. Given the expected isotropic distribution of component spins of binary black holes in gas-free dynamical environments, the presence of antialigned or in-plane spins with respect to the orbital angular momentum is considered a tell-tale sign of a merger's dynamical origin. Even in the scenario where birth spins of black holes are low, hierarchical mergers attain large component spins due to the orbital angular momentum of the prior merger. However, measuring such spin configurations is difficult. Here, we quantify the efficacy of the spin parameters encoding aligned-spin (χ eff) and in-plane spin (χ  p ) at classifying such hierarchical systems. Using Monte Carlo cluster simulations to generate a realistic distribution of hierarchical merger parameters from globular clusters, we can infer mergers' χ eff and χ  p . The cluster populations are simulated using Advanced LIGO-Virgo sensitivity during the detector network's third observing period and projections for design sensitivity. Using a "likelihood-ratio"-based statistic, we find that ∼2% of the recovered population by the current gravitational-wave detector network has a statistically significant χ  p  measurement, whereas no χ eff measurement was capable of confidently determining a system to be antialigned with the orbital angular momentum at current detector sensitivities. These results indicate that measuring spin-precession through χ  p  is a more detectable signature of hierarchical mergers and dynamical formation than antialigned spins.

Keywords: Gravitational waves, Bayesian statistics, Stellar mass black holes, Star clusters
Exploring the Impact of the Aging Effect on Inferred Properties of Solar Coronal Mass Ejections. In situ measurements of coronal mass ejections (CMEs) when they pass over an interplanetary probe are one of the main ways we directly measure their properties. However, such in situ profiles are subject to several observational constraints that are still poorly understood. This work aims at quantifying one of them, namely, the aging effect, using a CME simulated with a three-dimensional magnetohydrodynamical code. The synthetic in situ profile and the instantaneous profile of the magnetic field strength differ more from each other when taken close to the Sun than far from it. Moreover, out of three properties we compute in this study (i.e., size, distortion parameter, and expansion speed), only the expansion speed shows a dependence of the aging as a function of distance. It is also the property that is the most impacted by the aging effect as it can amount to more than 100 km s‑1 for CMEs observed closer than 0.15 au. This work calls for caution when deducing the expansion speed from CME profiles when they still are that close to the Sun since the aging effect can significantly impact the derived properties.

Keywords: Solar coronal mass ejections, Heliosphere, Magnetohydrodynamical simulations
Cosmology with Galaxy Photometry Alone. We present the first cosmological constraints using only the observed photometry of galaxies. Villaescusa-Navarro et al. recently demonstrated that the internal physical properties of a single simulated galaxy contain a significant amount of cosmological information. These physical properties, however, cannot be directly measured from observations. In this work, we present how we can go beyond theoretical demonstrations to infer cosmological constraints from actual galaxy observables (e.g., optical photometry) using neural density estimation and the CAMELS suite of hydrodynamical simulations. We find that the cosmological information in the photometry of a single galaxy is limited. However, we combine the constraining power of photometry from many galaxies using hierarchical population inference and place significant cosmological constraints. With the observed photometry of ∼20,000 NASA-Sloan Atlas galaxies, we constrain   ${{\rm{\Omega }}}_{m}={0.323}_{-0.095}^{+0.075}$   and   ${\sigma }_{8}={0.799}_{-0.085}^{+0.088}$  .

Keywords: Galaxy formation, Neural networks, Cosmological parameters, Astrostatistics, Magnetohydrodynamical simulations
Energetic Neutral Atoms Detected in the 2022 February 15 Solar Energetic Particle Event. Energetic neutral atoms (ENAs) are expected to be produced near the Sun during large solar energetic particle (SEP) events. However, their detection by SEP instruments near 1 au has been limited. The clearest reported measurement has been from the Solar Terrestrial Relations Observatory (STEREO) during the 2006 December 5 SEP event. Additional evidence of ENAs has been found through reanalysis of observations by the Solar Anomalous and Magnetospheric Particle Explorer obtained near the equator in low Earth orbit and associated with several large X-ray flares and fast coronal mass ejections (CMEs). Here we describe another detection of ENAs from the STEREO Low Energy Telescope associated with the large 2022 February 15 SEP event. Given the timing and spectrum of the ENAs and the location of the source region (behind the east limb from STEREO's viewpoint), these ENAs are most likely a result of acceleration by a CME-driven shock when the CME was at approximately 2–3 R S. The possibility of a postflare loop origin is considered unlikely.

Keywords: Solar energetic particles, Solar activity, Solar coronal mass ejections
The Disappearance of the Blue and Luminous Progenitor of the Type IIn SN 2010jl. Type IIn supernovae (SNe) exhibit narrow hydrogen lines that arise from the strong interaction between ejecta and circumstellar material. It remains poorly understood, however, what progenitor stars give rise to these explosions. In this work, we perform a detailed analysis of the progenitor and environment of the nearby Type IIn SN 2010jl. With newer images taken by the Hubble Space Telescope, we confirm that the previously reported progenitor candidate is a blend of the progenitor itself and a field star cluster in its close vicinity. SN 2010jl has now become much fainter than the progenitor. The progenitor is very blue and luminous with an effective temperature of log T eff/K = 4.26  ${}_{-0.09}^{+0.11}$   and a luminosity of log L/L ⊙ = 6.52  ${}_{-0.16}^{+0.20}$  . It is located in a very young star-forming region, but its luminosity is much higher than that expected from the environmental stellar populations. We suggest that the progenitor was in outburst when observed. Its nature and evolutionary history remain to be investigated.

Keywords: Luminous blue variable stars, Massive stars, Core-collapse supernovae, Stellar mass loss
Mid-infrared Spectrum of the Disk around the Forming Companion GQ Lup B Revealed by JWST/MIRI. GQ Lup B is a forming brown dwarf companion (M ∼ 10─30 M J) showing evidence for an infrared excess associated with a disk surrounding the companion itself. Here we present mid-infrared (MIR) observations of GQ Lup B with the Medium Resolution Spectrometer (MRS) on JWST, spanning 4.8─11.7 μm. We remove the stellar contamination using reference differential imaging based on principal component analysis, demonstrating that the MRS can perform high-contrast science. Our observations provide a sensitive probe of the disk surrounding GQ Lup B. We find no sign of a silicate feature, similar to other disks surrounding very low-mass objects, which likely implies significant grain growth (  ${a}_{\min }\gtrsim 5$   μm) and potentially dust settling. Additionally, we find that if the emission is dominated by an inner wall, the disk around the companion might have an inner cavity larger than the one set by sublimation. Conversely, if our data probe the emission from a thin flat disk, we find the disk to be very compact. More observations are required to confirm this findings and assess the vertical structure of the disk. This approach paves the path to the future study of circumplanetary disks and their physical properties. Our results demonstrate that MIR spectroscopic observations can reveal the physical characteristics of disks around forming companions, providing unique insights into the formation of giant planets, brown dwarfs, and their satellites.

Keywords: High contrast spectroscopy, Planet formation
JWST/MIRI Detection of Suprathermal OH Rotational Emissions: Probing the Dissociation of the Water by Lyα Photons near the Protostar HOPS 370. Using the MIRI medium-resolution spectrometer on JWST, we have detected pure rotational, suprathermal OH emissions from the vicinity of the intermediate-mass protostar HOPS 370 (OMC2/FIR3). These emissions are observed from shocked knots in a jet/outflow and originate in states of rotational quantum number as high as 46 that possess excitation energies as large as E  U /k = 4.65 × 104 K. The relative strengths of the observed OH lines provide a powerful diagnostic of the ultraviolet radiation field in a heavily extinguished region (A  V  ∼ 10–20) where direct UV observations are impossible. To high precision, the OH line strengths are consistent with a picture in which the suprathermal OH states are populated following the photodissociation of water in its   $\tilde{B}-X$   band by ultraviolet radiation produced by fast (∼80 km s‑1) shocks along the jet. The observed dominance of emission from symmetric (  $A^{\prime} $  ) OH states over that from antisymmetric (A″) states provides a distinctive signature of this particular population mechanism. Moreover, the variation of intensity with rotational quantum number suggests specifically that Lyα radiation is responsible for the photodissociation of water, an alternative model with photodissociation by a 104 K blackbody being disfavored at a high level of significance. Using measurements of the Brα flux to estimate the Lyα production rate, we find that ∼4% of the Lyα photons are absorbed by water. Combined with direct measurements of water emissions in the ν 2 = 1 ‑ 0 band, the OH observations promise to provide key constraints on future models for the diffusion of Lyα photons in the vicinity of a shock front.

Keywords: Infrared astronomy, Protostars, Molecular gas
Chandra HETG X-Ray Spectra and Variability of π Aqr, a γ Cas-type Be Star. High-resolution X-ray spectra of π Aqr, a γ Cas-type star, obtained with the Chandra/HETG spectrometer, revealed emission lines of H-like ions of Mg, Si, S, and Fe; a strong, hard continuum; and a lack of He-like ions, indicating the presence of very hot thermal plasma. The X-ray light curve showed significant fluctuations, with coherent variability at a period of about 3400 s in one observation. The hardness ratio was relatively constant except for one observation in which the spectrum was much harder and more absorbed. We interpret the X-ray emission as arising from accretion onto the secondary, which is likely a magnetic white dwarf, an intermediate polar system.

Keywords: X-ray astronomy, High resolution spectroscopy, Gamma Cassiopeiae stars, White dwarf stars, Early-type emission stars, Be stars
Biogenic Sulfur Gases as Biosignatures on Temperate Sub-Neptune Waterworlds. Theoretical predictions and observational data indicate a class of sub-Neptune exoplanets may have water-rich interiors covered by hydrogen-dominated atmospheres. Provided suitable climate conditions, such planets could host surface liquid oceans. Motivated by recent JWST observations of K2-18 b, we self-consistently model the photochemistry and potential detectability of biogenic sulfur gases in the atmospheres of temperate sub-Neptune waterworlds for the first time. On Earth today, organic sulfur compounds produced by marine biota are rapidly destroyed by photochemical processes before they can accumulate to significant levels. Domagal-Goldman et al. suggest that detectable biogenic sulfur signatures could emerge in Archean-like atmospheres with higher biological production or low UV flux. In this study, we explore biogenic sulfur across a wide range of biological fluxes and stellar UV environments. Critically, the main photochemical sinks are absent on the nightside of tidally locked planets. To address this, we further perform experiments with a 3D general circulation model and a 2D photochemical model (VULCAN 2D) to simulate the global distribution of biogenic gases to investigate their terminator concentrations as seen via transmission spectroscopy. Our models indicate that biogenic sulfur gases can rise to potentially detectable levels on hydrogen-rich water worlds, but only for enhanced global biosulfur flux (≳20 times modern Earth's flux). We find that it is challenging to identify DMS at 3.4 μm where it strongly overlaps with CH4, whereas it is more plausible to detect DMS and companion byproducts, ethylene (C2H4) and ethane (C2H6), in the mid-infrared between 9 and 13 μm.

Keywords: Exoplanet atmospheric composition , Biosignatures, Exoplanet atmospheres
Cascade Radiations of e <SUP>±</SUP> from γγ-annihilation Process as an Extra Component of the Early Optical/X-Ray Afterglows of Gamma-Ray Bursts. Chromatic break and/or plateau observed in the early optical and X-ray afterglow lightcurves challenge the conventional external shock models of gamma-ray bursts (GRBs). Detection of TeV gamma-ray afterglows indicates strong gamma-ray production within the afterglow jets. We investigate the cascade radiations of the e ± production via the γ γ interaction in the jets. Our numerical calculations show that the cascade synchrotron emission can make a significant contribution to the early optical/X-ray afterglows. The combination of the primary and cascade emission fluxes can shape a chromatic break and/or plateau in the early optical/X-ray lightcurves, depending on the jet properties. Applying our model to GRBs 050801 and 080310, we found that their optical plateaus and the late X-ray/optical lightcurves can be explained with our model in reasonable parameter values. We suggest that such a chromatic optical plateau could be a signature of strong e ± production in GRB afterglow jets. The TeV gamma-ray flux of such GRBs should be significantly reduced and hence tends to be detectable for those GRBs that have a single power-law decaying optical afterglow lightcurve.

Keywords: Gamma-ray bursts, Non-thermal radiation sources, High energy astrophysics
Annual and Seasonal Occurrence Pattern of Auroral Kilometric Radiation Associated with the Interplanetary Magnetic Field. Auroral kilometric radiation (AKR) is a widely existing strong radio emission from the Earth's magnetosphere and is generated by suprathermal (1–10 keV) electrons in the polar cavity. Previous works have demonstrated that AKR can contribute to the coupling of the magnetosphere–ionosphere–atmosphere, but its relation to the interplanetary magnetic field (IMF) has not been studied so far. Here, we examine the data of Van Allen Probes and identify a total of 5000 AKR events from 2012 October to 2019 July. Most AKR events (4282) correspond to the dominant parallel component ${B}_{\parallel }(=\sqrt{{({B}_{x})}^{2}+{({B}_{y})}^{2}})$ of IMF. There are the most (1391) events in 2018 (the solar minimum year) and the least (258) events in 2014 (the solar maximum year), corresponding to more (less) occurrences for the longer duration (&gt; 30 minutes) of southward IMF (B  z  &lt; 0) in 2018 (2014). In the Earth's Northern Hemisphere, there are the most (865) events in the autumn (August–October), corresponding to dominant B  x  &lt; 0. In the Earth's Southern Hemisphere, there are the most (830) events in the autumn (February–April), corresponding to dominant B  x  &gt; 0. The probable reason for the above results is that the longer duration of B  z  &lt; 0 can yield the longer magnetic reconnection, and the dominant B  x  &lt; 0 (B  x  &gt; 0) is favorable for the single-lobe magnetic reconnection in the northern (southern) hemisphere, allowing more suprathermal electrons into the polar source cavity and generating more AKRs. These current results suggest that IMF is very important for the occurrence of AKR and can be widely applied to similar auroral radio emissions in other magnetized planets of the solar system. *Released on March 1st, 2024.

Keywords: Space plasmas, Interplanetary magnetic fields, Magnetospheric radio emissions
The Kinematic and Chemical Properties of the Close-in Planet Host Star 8 UMi. A recent study by Hon et al. reported that a close-in planet around the red clump star, 8 UMi, should have been engulfed during the expansion phase of its parent star's evolution. They explained the survival of this exoplanet through a binary-merger channel for 8 UMi. The key to testing this formation scenario is to derive the true age of this star: is it an old "imposter" resulting from a binary merger, or a genuinely young red clump giant? To accomplish this, we derive kinematic and chemical properties for 8 UMi using astrometric data from Gaia DR3 and the element-abundance pattern measured from a high-resolution (R ∼ 75,000) spectrum taken by SOPHIE. Our analysis shows that 8 UMi is a normal thin-disk star with orbital rotation speed of V  ϕ  = 244.96 km s‑1, and possesses a solar metallicity ([Fe/H] = ‑0.05 ± 0.07) and α-element-abundance ratio ([α/Fe] = +0.01 ± 0.03). By adopting well-established relationships between age and space velocities/elemental abundances, we estimate a kinematic age of   ${3.50}_{-2.00}^{+3.00}$   Gyr, and a chemical age of   ${3.25}_{-1.50}^{+2.50}$   Gyr from [C/N] and 3.47 ± 1.96 Gyr from [Y/Mg] for 8 UMi, respectively. These estimates are consistent with the isochrone-fitting age (  ${1.90}_{-0.30}^{+1.15}$   Gyr) of 8 UMi, but are all much younger than the timescale required in a binary-merger scenario. This result challenges the binary-merger model; the existence of such a closely orbiting exoplanet around a giant star remains a mystery yet to be resolved.

Keywords: Galaxy kinematics, Stellar evolution, Chemical abundances, Planet hosting stars
Calcium Chemistry in Carbon-rich Circumstellar Environments: The Laboratory and Astronomical Discovery of Calcium Dicarbide, CaC<SUB>2</SUB>. Calcium dicarbide, CaC2, has been characterized at high resolution in the laboratory, and its main isotopologue, 40CaC2, has been assigned to 14 rotational emission lines between 14 and 115 GHz, including 12 previously unassigned lines, in the expanding molecular envelope of the evolved carbon star IRC+10216. Aided by high-level quantum calculations and measurements of multiple isotopologues, CaC2 is determined to be a T-shaped molecule with a highly ionic bond linking the metal atom to the C2 unit, very similar in structure to isovalent magnesium dicarbide (MgC2). The excitation of CaC2 is characterized by a very low rotational temperature of 5.8 ± 0.6 K and a kinetic temperature of 36 ± 16 K, similar to values derived for MgC2. On the assumption that the emission originates from a 30″ shell in IRC+10216, the column density of CaC2 is (5.6 ± 1.7) × 1011 cm‑2. CaC2 is only the second Ca-bearing molecule besides CaNC and only the second metal dicarbide besides MgC2 identified in space. Owing to the similarity between the predicted ion–molecule chemistry of Ca and Mg, a comparison of the CaC2 abundance with that of MgC2 and related species permits empirical inferences about the radiative association–dissociative recombination processes postulated to yield metal-bearing molecules in IRC+10216 and similar objects. * This work is based on observations done using the 100 m Green Bank Telescope (GBT), the Yebes 40 m telescope (projects 19A010, 20A017, 20B014, and 21A019), and the IRAM 30 m telescope. The 100 m GBT is an instrument of the Green Bank Observatory, which is a major research facility funded by the National Science Foundation and operated by Associated Universities, Inc. The Yebes 40 m radio telescope at Yebes Observatory is operated by the Spanish National Geographic Institute (Instituto Geográfico Nacional, IGN). IRAM is supported by INSU/CNRS (France), Max-Planck-Gesellschaft (MPG; Germany), and IGN (Spain).

Keywords: Circumstellar envelopes, Carbon stars, Laboratory astrophysics, Metal-containing molecules
Evidence for Plasmoid-mediated Magnetic Reconnection during a Small-scale Flare in the Partially Ionized Low Solar Atmosphere. Magnetic reconnection plays a crucial role in the energy release process for different kinds of solar eruptions and activities. The rapid solar eruption requires a fast reconnection model. Plasmoid instability in the reconnecting current sheets is one of the most acceptable fast reconnection mechanisms for explaining the explosive events in the magnetohydrodynamics (MHD) scale, which is also a potential bridge between the macroscopic MHD reconnection process and microscale dissipations. Plenty of high-resolution observations indicate that the plasmoid-like structures exist in the high-temperature solar corona, but such evidences are very rare in the lower solar atmosphere with partially ionized plasmas. Utilizing joint observations from the Goode Solar Telescope and the Solar Dynamics Observatory, we discovered a small-scale eruptive phenomenon in NOAA Active Region 13085, characterized by clear reconnection cusp structures, supported by nonlinear force-free field extrapolation results. The plasmoid-like structures with a size of about 150 km were observed to be ejected downward from the current sheet at a maximum velocity of 24 km s‑1 in the Hα line wing images, followed by enhanced emissions at around the postflare loop region in multiple wavelengths. Our 2.5D high-resolution MHD simulations further reproduced such a phenomenon and revealed reconnection fine structures. These results provide comprehensive evidences for the plasmoid-mediated reconnection in partially ionized plasmas, and suggest a unified reconnection model for solar flares with different length scales from the lower chromosphere to the corona.

Keywords: Solar activity, Solar chromospheric heating, Solar magnetic reconnection
Overmassive Black Holes at Cosmic Noon: Linking the Local and the High-redshift Universe. We report for the first time a sample of 12 supermassive black holes (SMBHs) hosted by low-mass galaxies at cosmic noon, i.e., in a redshift range consistent with the peak of star formation history: z ∼ 1─3. These black holes are 2 orders of magnitude too massive for the stellar content of their hosts when compared with the local relation for active galaxies. These overmassive systems at cosmic noon share similar properties with the high-z sources found ubiquitously in recent James Webb Space Telescope (JWST) surveys (same range of black-hole-to-stellar-mass ratio, bolometric luminosity, and Eddington ratio). We argue that black hole feedback processes, for which there is possible evidence in five of the sources, and the differing environments in galactic nuclei at these respective epochs play a key role in these overmassive systems. These findings contribute to our understanding of the growth and coevolution of SMBHs and their host galaxies across cosmic time, offering a link between the early Universe (z &gt; 4) observed by JWST and observations of the present-day Universe (z ≲ 1).

Keywords: Active galaxies