Sazuna/UAT_keywords huggingface dataset:
Entrapment of Hypervolatiles in Interstellar and Cometary H<SUB>2</SUB>O and CO<SUB>2</SUB> Ice Analogs. Planets and planetesimals acquire their volatiles through ice and gas accretion in protoplanetary disks. In these disks, the division of volatile molecules between the condensed and gaseous phases determines the quantity of volatiles accreted by planets in different regions of the disk. This division can be strongly affected by entrapment of volatiles into less volatile ice matrices, resulting in different radial profiles of common volatiles and elemental ratios than would otherwise be expected. In this study we use laboratory experiments to explore the ability of abundant interstellar and cometary ice matrices, i.e., H2O and CO2, to trap the hypervolatiles 13CO, 12CH4, 15N2, and Ar. We measure entrapment efficiencies through temperature programmed desorption for two ice thicknesses (10 and 50 monolayers) and two mixing ratios (3:1 and 10:1) for each matrix:volatile combination. We find that ice entrapment efficiencies increase with ice thickness and ice mixing ratio to a maximum of ~65% for all hypervolatiles. Entrapment efficiencies are comparable for all hypervolatiles, and for the two ice matrices. We further find that the entrapment efficiency is relatively insensitive to the ice deposition temperature between 10 and 30 K with the possible exception of CH4 in CO2 ice. Together these results suggest that hypervolatile entrapment at low temperatures (&lt;30 K) is a remarkably robust and species-independent process.

Keywords: Chemical abundances, Astrochemistry, Planetary system formation, Protoplanetary disks, Planet formation
The EB Correlation in Resolved Polarized Images: Connections to the Astrophysics of Black Holes. We present an in-depth analysis of the newly proposed correlation function in visibility space, between the E and B modes of linear polarization, hereafter the EB correlation, for a set of time-averaged general relativistic magnetohydrodynamical simulations compared with the phase map from different semianalytic models and the Event Horizon Telescope (EHT) 2017 data for M87*. We demonstrate that the phase map of time-averaged EB correlation contains novel information that might be linked to black hole (BH) spin, accretion state, and electron temperature. A detailed comparison with a semianalytic approach with different azimuthal expansion modes shows that to recover the morphology of real/imaginary part of the correlation function and its phase, we require higher orders of azimuthal modes. To extract the phase features, we use Zernike polynomial reconstruction developing an empirical metric to break degeneracies between models with different BH spins that are qualitatively similar. We use a set of geometrical ring models with various magnetic and velocity field morphologies, showing that both the image space and visibility-based EB-correlation morphologies in magnetically arrested disk simulations can be explained with simple fluid and magnetic field geometries as used in ring models. Standard and normal evolutions by contrast are harder to model, demonstrating that the simple fluid and magnetic field geometries of ring models are not sufficient to describe them owing to higher Faraday rotation depths. A qualitative comparison with the EHT data demonstrates that some of the features in the phase of EB correlation might be well explained by the current models for BH spins and electron temperatures, while others require larger theoretical surveys.

Keywords: Black hole physics, Supermassive black holes, Event horizons
Jet-powered Turbulence in Common Envelope Evolution. We conduct a three-dimensional hydrodynamical simulation of common envelope evolution (CEE) where a neutron star (NS) spirals in inside the envelope of a red supergiant star in a predetermined orbit. We find that the jets shed pairs of vortices in an expanding spiral pattern, inflate two expanding spirally shaped low-density bubbles, one above and one below the equatorial plane, and deposit angular momentum to the envelope. In the simulation we do not include the gravity of the NS such that all effects we find are solely due to the jets that the spiraling-in NS launches. The angular momentum that the jets deposit into the envelope is of the same order of magnitude as the orbital angular momentum and has the same direction. The turbulence that the jets induce in the common envelope might play a role in transporting energy and angular momentum. The jet-deposited energy that is radiated away (a process not studied here) leads to a transient event that is termed a common envelope jets supernova (CEJSN) and might mimic an energetic core collapse supernova. The turbulence and the spiral pattern that we explore here might lead to bumps in the late light curve of the CEJSN when different segments of the ejected envelope collide with each other. This study emphasizes the roles that jets can play in CEE (including jets launched by black hole companions) and adds to the rich variety of processes in CEJSN events.

Keywords: Stellar jets, Common envelope evolution
Chance Coincidences between Black Hole Low-mass X-Ray Binaries and Supernova Remnants. I argue that black hole low-mass X-ray binaries (BH LMXBs) are very unlikely to be physically associated with supernova remnants (SNRs). The timescales of BH LMXBs are so much longer than those of SNRs, that there is only a 0.2% chance of any BH LMXB being identified within its natal SNR. However, the probability of a BH LMXB being projected within an SNR is significant; I estimate that two BH LMXBs should be projected within SNRs from our perspective. I look more closely at the suggestion by Balakrishnan and collaborators of an association between the BH X-ray binary Swift J1728.9-3613 and the SNR G351.9-0.9, and show that this is most likely a chance coincidence.

Keywords: Supernova remnants, Low-mass x-ray binary stars, Astrophysical black holes, Stellar evolution
Polarization Signature of Companion-fed Supernovae Arising from BH-NS/BH Progenitor Systems. The formation of black hole-neutron star (BH-NS) or BH-BH systems may be accompanied by special supernova (SN) signals, due to the accretion feedback from the companion BH. The additional heating, which is mainly attributed to the Blandford-Payne mechanism, would disrupt the isotropic nature of the luminosity distribution on the surface of the SN ejecta, leading to the appearance of polarization. Here we develop a three-dimensional Monte Carlo polarization simulation code to conduct simulations for these special SNe. We find that the maximum polarization level of ~2% occurs at the peak time of SN emission in the "close-binary" scenario, while in the "faraway-binary" case maximum polarization (i.e., ~0.7%) is observed at a considerably later time than the peak of the SN. The magnitude of polarization is dependent on the degree of unevenness in the luminosity distribution and the angle between the line of sight and the equatorial direction. When considering the geometric distortion of SN ejecta at the same time, the magnitude of polarization may either increase (for a oblate ellipsoidal shape) or decrease (for a prolate ellipsoidal shape). The polarization signatures represent a promising auxiliary instrument to facilitate the identification of the companion-fed SNe. Moreover, comparing the event rate of these special SNe with the event rate density of LIGO-Virgo-detected BH-NS/BH systems could further help to distinguish the BH-NS/BH formation channel.

Keywords: Gravitational waves, Polarimetry, Supernovae, Black holes
Unusually Powerful Flare Phenomenon of the Water Maser in W51 and the Possibility of Detecting Gravitational Radiation from It. Because of detailed monitoring of the 22.2 GHz water maser, carried out from 2021 October to 2023 May, a very powerful flare phenomenon was detected in the galactic object W51 near the radial velocity of 60 km s-1 with the amplitude of 140 kJy. A phenomenon of this magnitude was unprecedented in the entire history of observations of the source. Eleven short flares were recorded. The exponential increase and decrease in the flare flux density while reducing in their spectral line widths indicated that water masers were in an unsaturated state during the flares. All flares were located at the top of the less powerful Flare 0 with the amplitude of 13.5 kJy and the spectral line half-width of 3.0 km s-1. Such a wide line of the water maser, as well as the amplitude, of the flare phenomenon are so far unique discoveries. The water maser of Flare 0 may have been saturated and created a significant input flux density for other flares of this phenomenon. The extremely high density of maser spots in a cluster led to their partial overlap on the observer's line of sight. This also confirmed the hypothesis about the need for a significant length of the path along which the generation of maser radiation occurs. New parameters of water masers and the most important physical conclusions have been obtained. The possibility of detecting gravitational waves from massive binary stars at the stage of evolution close to merging is considered for the case of W51 Main.

Keywords: Water masers, Astrophysical masers, Star forming regions
Walkaway Star Candidates in IC 348 and Their Possible Birthplaces. Observations and theories reveal that star-forming regions eject their members during the early evolution of the cluster. We present an initial search for stars ejected from the young cluster IC 348 based on an analysis of Gaia EDR3 astrometry of previously identified members. We identify six candidate walkaway stars with projected velocities of 5-8 km s-1. The candidate with properties most consistent with a walkaway star, V701 Per, was likely ejected from a small group to the west of IC 348. Three candidates are currently located or have proper motions that trace back to the center of IC 348, though their classification as walkaway stars may also be affected by large astrometric errors. Two other candidate walkaway stars were likely born in other subgroups around IC 348 within the Perseus star-forming region. Since our search criteria are restricted to previously identified members of IC 348, we did not identify any stars that were ejected at high velocities and traveled far from the cluster. Our study suggests that ejections have potentially occurred in both the central region of IC 348 and other subgroups in Perseus. Extending the search range will lead to more candidate ejections and constrain the dynamic properties and evolution of IC 348 by comparing with simulations.

Keywords: Pre-main sequence stars, Stellar dynamics, Proper motions
UV Signatures of Magnetar Formation and Their Crucial Role for GW Detection. The emission from shock breakouts (SBOs) represents the earliest electromagnetic (EM) signal emitted by cataclysmic events involving the formation or the merger of neutron stars (NSs). As such, SBOs carry unique information on the structure of their progenitors and on the explosion energy. The characteristic SBO emission is expected in the UV range, and its detection is one of the key targets of the ULTRASAT satellite. Among SBO sources, we focus on a specific class involving the formation of fast-spinning magnetars in the core-collapse of massive stars. Fast-spinning magnetars are expected to produce a specific signature in the early UV supernova light curve, powered by the extra spin energy quickly released by the NS. Moreover, they are considered as optimal candidates for the emission of long-transient gravitational wave (GW) signals, the detection of which requires early EM triggers to boost the sensitivity of dedicated GW search pipelines. We calculate early supernova UV light curves in the presence of a magnetar central engine, as a function of the explosion energy, ejecta mass, and magnetar parameters. We then estimate the ULTRASAT detection horizon (z &lt; 0.15) as a function of the same physical parameters, and the overall expected detection rate, finding that magnetar-powered SBOs may represent up to 1/5 of the total events detected by ULTRASAT. Moreover, at the expected sensitivity of the LIGO/Virgo/Kagra O5 science run, one such event occurring within 5 Mpc will provide an ideal trigger for a GW long-transient search. Future GW detectors like the Einstein Telescope will push the horizon for joint EM-GW detections to 35-40 Mpc.

Keywords: Magnetars, Core-collapse supernovae, Near ultraviolet astronomy
High-redshift Galaxy Candidates at z = 9-10 as Revealed by JWST Observations of WHL0137-08. We report the discovery of four galaxy candidates observed 450-600 Myr after the Big Bang with photometric redshifts between z ~ 8.3 and 10.2 measured using James Webb Space Telescope (JWST) NIRCam imaging of the galaxy cluster WHL0137-08 observed in eight filters spanning 0.8-5.0 μm, plus nine Hubble Space Telescope filters spanning 0.4-1.7 μm. One candidate is gravitationally lensed with a magnification of μ ~ 8, while the other three are located in a nearby NIRCam module with expected magnifications of μ ≲ 1.1. Using SED fitting, we estimate the stellar masses of these galaxies are typically in the range $\mathrm{log}{M}_{\star }/{M}_{\odot }$ = 8.3-8.7. All appear young, with mass-weighted ages &lt;240 Myr, low dust content A  V  &lt; 0.15 mag, and specific star formation rates sSFR ~0.25-10 Gyr-1 for most. One z ~ 9 candidate is consistent with an age &lt;5 Myr and an sSFR ~10 Gyr-1, as inferred from a strong F444W excess, implying [O III ]+H β rest-frame equivalent width ~2000 Å, although an older z ~ 10 object is also allowed. Another z ~ 9 candidate is lensed into an arc 2.″4 long with a magnification of μ ~ 8. This arc is the most spatially resolved galaxy at z ~ 9 known to date, revealing structures ~30 pc across. Follow-up spectroscopy of WHL0137-08 with JWST/NIRSpec will be useful to spectroscopically confirm these high-redshift galaxy candidates and to study their physical properties in more detail.

Keywords: Galaxy clusters, Strong gravitational lensing, High-redshift galaxies
Properties of Electron-scale Magnetic Reconnection at a Quasi-perpendicular Shock. Recent spacecraft observations have shown that magnetic reconnection occurs commonly in turbulent environments at shocks. At quasi-perpendicular shocks, magnetic field lines are bent by the back-streaming reflected ions, which form a current sheet in the foot region, and then electron-scale reconnection occurs when the current sheet is fragmented at the shock front. Here we study magnetic reconnection at a quasi-perpendicular shock by using a two-dimensional particle-in-cell simulation. Collective properties of the reconnection sites from the shock transition to the downstream region are analyzed by adopting a statistical approach to the simulation data. Reconnecting current sheets are found to be densely distributed near the shock front, with a reconnection electric field larger than those in the downstream region. By tracing a reconnection site from its formation until it is convected downstream, we show the reconnection proceeds intermittently after an active stage near the shock front. Our tracing further shows that, in addition to being originated from the shock front, reconnection in the downstream region can also occur locally, driven by turbulent flows therein. The results help us better understand the evolution of electron-scale reconnection at a perpendicular shock.

Keywords: Space plasmas, Planetary bow shocks, Solar magnetic reconnection, Plasma physics
Searching for the Role of Mergers in Fast and Early SMBH Growth: Morphological Decomposition of Quasars and Their Hosts at z   4.8. We present rest-frame ultraviolet images of six luminous quasars at z ~ 4.8 obtained with the Hubble Space Telescope (HST). These quasars exhibit a wide range of star formation rates (SFRs) and lie in a wide range of environments. We carefully model and subtract the point-like quasar emission and investigate the morphology of the underlying host galaxies at kpc scales. The residual images allowed identification of potential companion sources, which enabled us to explore the role of galaxy merger scenarios in the coevolution of the quasars and their hosts. We also search for the mechanism driving extreme SFRs in three of the six quasars. We find that the rate of detection of potential companions to the host galaxies does not follow trends between high- and low-SFR sources; i.e., the HST imaging suggests that both high- and low-SFR sources are found in both dense and sparse galactic environments. The suggested role of major mergers driving extreme SFRs cannot be supported by the multiwavelength data in hand. Three of four companion sources, previously revealed by submillimeter observations, are not detected in the HST images of three of our quasars. An adapted high-resolution imaging strategy focused on high-SFR sources and extended to a larger quasar sample is required in order to determine the role of mergers in the processes of star formation and supermassive black hole growth at high redshift.

Keywords: AGN host galaxies, Supermassive black holes, Quasars, Star formation, Galaxy mergers
A Wideband Polarization Observation of Hydra A with the Jansky Very Large Array. We present the results of a wideband high-resolution polarization study of Hydra A, one of the most luminous FR I radio galaxies known and among the most well studied. The radio emission from this source displays extremely large Faraday rotation measures (RMs), ranging from -12,300 rad m-2 to 5000 rad m-2, the majority of which are believed to originate from magnetized thermal gas external to the radio tails. The radio emission from both tails strongly depolarizes with decreasing frequency. Depolarization, as a function of wavelength, is commonly nonmonotonic, often showing oscillatory behavior, with strongly nonlinear rotation of the polarization position angle with λ 2. A simple model, based on the RM screen derived from the high-frequency, high-resolution data, predicts the lower frequency depolarization remarkably well. The success of this model indicates the majority of the depolarization can be attributed to fluctuations in the magnetic field on scales &lt;1500 pc, suggesting the presence of turbulent magnetic field/electron density structures on subkiloparsec scales within a Faraday rotating medium.

Keywords: Galaxy clusters, Extragalactic radio sources, Radio galaxies, Extragalactic astronomy, Intracluster medium, Magnetic fields, Extragalactic magnetic fields
GHOST Commissioning Science Results: Identifying a New Chemically Peculiar Star in Reticulum II. The Gemini High-resolution Optical SpecTrograph (GHOST) is the newest high-resolution spectrograph to be developed for a large-aperture telescope, recently deployed and commissioned at the Gemini-South telescope. In this paper, we present the first science results from the GHOST spectrograph taking during its commissioning runs. We have observed the bright metal-poor benchmark star HD 122563, along with two stars in the ultrafaint dwarf galaxy Reticulum II (Ret II), one of which was previously identified as a candidate member, but did not have a previous detailed chemical abundance analysis. We find that this candidate (GDR3 0928) to be a bona fide member of Ret II, and from a spectral synthesis analysis it is also revealed to be a CEMP-r star, with significant enhancements in several light elements (C, N, O, Na, Mg, and Si), in addition to featuring an r-process enhancement like many other Ret II stars. The light-element enhancements in this star resemble the abundance patterns seen in the CEMP-no stars of other ultrafaint dwarf galaxies, and are thought to have been produced by an independent source from the r-process. These unusual abundance patterns are thought to be produced by faint supernovae, which may be produced by some of the earliest generations of stars.

Keywords: High resolution spectroscopy, Observational astronomy, Dwarf galaxies, Chemical abundances, Chemically peculiar stars
TESS Photometric Variability of Young Brown Dwarfs in the Taurus Star-forming Region. We present a comprehensive analysis of TESS high-quality light curves from sectors 43 and 44 of a few samples of young (~2-3 Myr) brown dwarfs in the Taurus molecular cloud. They are well characterized and bona fide members of Taurus. We aim to search for the fast rotations of brown dwarfs and to picturize their dynamic atmosphere and surface features. Out of 11 young BDs, we found that 72% are periodic, in the period range of 1-7 days; among them, three BDs have periods &lt;1.5 day and the period of one object is estimated for the first time. The sinusoidal periodic variations are related to a large spot or group of small spots corotating with the objects. Interestingly, we have detected four flare events in three young BDs, with one object, MHO 4, showing two flares in two different sectors. From the flared light curves, we have estimated the total bolometric flared energy in a range of 1035-1036 erg, which is close to the superflare energy range (≥1034 erg). To produce such kinds of superflare events, we have calculated the required magnetic field strength, which comes out at the order of a few kilogauss. Such superflares have a strong effect on the habitability of planets around M dwarfs.

Keywords: M dwarf stars, Starspots, Stellar activity, Pre-main sequence stars, Stellar flares, Variable stars, Stellar rotation
Detection Possibility of Continuous Gravitational Waves from Rotating Magnetized Neutron Stars. In recent decades, several neutron stars (NSs), particularly pulsars, with masses of M &gt; 2 M ⊙ have been observed. On the other hand, the existence of massive white dwarfs, even violating the Chandrasekhar mass limit, was inferred from the peak luminosities of Type Ia supernovae. Hence, there is a generic question of the origin of massive compact objects. Here we explore the existence of massive, magnetized, rotating NSs with the soft and steep equations of state by solving axisymmetric stationary stellar equilibria in general relativity. For our purposes, we consider the Einstein equation solver for stellar structure XNS code. Such rotating NSs with magnetic fields and rotation axes misaligned, and hence a nonzero obliquity angle, can emit continuous gravitational waves (GWs), which can be detected by upcoming detectors, e.g., the Einstein Telescope, etc. We discuss the decay of the magnetic field, angular velocity, and obliquity angle with time due to angular momentum extraction by GWs and dipole radiation, which determine the timescales related to the GW emission. Further, in the Alfvén timescale, a differentially rotating, massive proto-NS rapidly settles into a uniformly rotating, less massive NS due to magnetic braking and viscosity. These explorations suggest that detecting massive NSs is challenging and sets a timescale for detection. We calculate the signal-to-noise ratio of GW emission, which confirms that any detector cannot detect them immediately, but that they are detectable by the Einstein Telescope and Cosmic Explorer over months of integration time, leading to direct detection of NSs.

Keywords: Neutron stars, Magnetic stars, Gravitation, Stellar magnetic fields, Gravitational wave sources, Pulsars, Gravitational waves, Astronomical radiation sources