Sazuna/UAT_keywords huggingface dataset:
ROME. III. The Arecibo Search for Star-Planet Interactions at 5 GHz. After nearly three decades of discovery, many exoplanetary systems have been studied and characterized in detail with one important exception: exoplanet magnetism. Although many surveys sought to detect magnetospheric radio emissions from exoplanets to directly measure their magnetic field strengths, they have yet to reveal an unambiguous detection. However, the indirect detection of exoplanet magnetic fields by measuring their influence on their host stars via magnetic star-planet interactions has recently gained prominence as an alternative method of discovery. This third paper of the Radio Observations of Magnetized Exoplanets series presents the results of a targeted radio survey of eight nearby exoplanet-hosting systems that may engage in star-planet interactions. This survey, conducted with the Arecibo radio telescope at ~5 GHz, has the greatest frequency coverage of any to date while providing millijansky-level sensitivity over &lt;1 s integration times. No exoplanet-induced stellar radio bursts were detected. The orbital phase coverage of candidate systems for magnetic star-planet interactions is described, and the survey results are examined within the context of the plasma flow-obstacle paradigm and searches for star-planet interactions at other wavelengths.

Keywords: Magnetospheric radio emissions, Exoplanets, Stellar activity, Non-thermal radiation sources, Star-planet interactions, Planetary magnetospheres
The Prevalence and Influence of Circumstellar Material around Hydrogen-rich Supernova Progenitors. Narrow transient emission lines (flash-ionization features) in early supernova (SN) spectra trace the presence of circumstellar material (CSM) around the massive progenitor stars of core-collapse SNe. The lines disappear within days after the SN explosion, suggesting that this material is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior to the explosion. We performed a systematic survey of H-rich (Type II) SNe discovered within less than 2 days from the explosion during the first phase of the Zwicky Transient Facility survey (2018-2020), finding 30 events for which a first spectrum was obtained within &lt;2 days from the explosion. The measured fraction of events showing flash-ionization features (&gt;36% at the 95% confidence level) confirms that elevated mass loss in massive stars prior to SN explosion is common. We find that SNe II showing flash-ionization features are not significantly brighter, nor bluer, nor more slowly rising than those without. This implies that CSM interaction does not contribute significantly to their early continuum emission, and that the CSM is likely optically thin. We measured the persistence duration of flash-ionization emission and find that most SNe show flash features for ≈5 days. Rarer events, with persistence timescales &gt;10 days, are brighter and rise longer, suggesting these may be intermediate between regular SNe II and strongly interacting SNe IIn.

Keywords: Core-collapse supernovae, Type II supernovae, Massive stars, Circumstellar matter, Supernovae
A NICER View on the 2020 Magnetar-like Outburst of PSR J1846-0258. We report on our monitoring of the strong-field magnetar-like pulsar PSR J1846-0258 with the Neutron Star Interior Composition Explorer (NICER) and the timing and spectral evolution during its outburst in 2020 August. Phase-coherent timing solutions were maintained from 2017 March through 2021 November, including a coherent solution throughout the outburst. We detected a large spin-up glitch of magnitude Δν/ν = 3 × 10-6 at the start of the outburst and observed an increase in pulsed flux that reached a factor of more than 10 times the quiescent level, a behavior similar to that of the 2006 outburst. Our monitoring observations in 2020 June and July indicate that the flux was rising prior to the Swift announcement of the outburst on 2020 August 1. We also observed several sharp rises in the pulsed flux following the outburst and the flux reached quiescent level by 2020 November. The pulse profile was observed to change shape during the outburst, returning to the preoutburst shape by 2021. Spectral analysis of the pulsed emission of NICER data shows that the flux increases result entirely from a new blackbody component that gradually fades away while the power law remains nearly constant at its quiescent level throughout the outburst. Joint spectral analysis of NICER and simultaneous NuSTAR data confirms this picture. We discuss the interpretation of the magnetar-like outburst and origin of the transient thermal component in the context of both a pulsar-like and a magnetar-like model.

Keywords: Neutron stars
Rapid Growth of Galactic Supermassive Black Holes through Accreting Giant Molecular Clouds during Major Mergers of Their Host Galaxies. Understanding the formation of the supermassive black holes (SMBHs) present in the centers of galaxies is a crucial topic in modern astrophysics. Observations have detected SMBHs with masses of 109 M ⊙ in the high-redshift galaxies with z ~ 7. However, how SMBHs grew to such huge masses within the first billion years after the Big Bang remains elusive. One possible explanation is that SMBHs grow quickly through the frequent mergers of galaxies, which provides sustainable gas to maintain rapid growth. This study presents the hydrodynamics simulations of the SMBHs' growth with their host galaxies using the GIZMO code. In contrast to previous simulations, we have developed a giant molecular cloud (GMC) model by separating molecular gas particles from atomic gas particles and then evolving them independently. During major mergers, we show that the more massive molecular gas particles' cloud bears stronger dynamical friction. Consequently, GMCs are substantially accreted onto the galactic centers that grow SMBHs from ~107 to ~109 M ⊙ within 300 Myr, which explains the rapid growth of SMBHs, and this accretion also triggers a violent starburst at the galactic center. Furthermore, we examine the impact of minor mergers on the bulge of a Milky Way-like galaxy and find that the size and mass of the bulge can increase from 0.92 to 1.9 kpc and from 4.7 × 1010 to 7 × 1010 M ⊙.

Keywords: Supermassive black holes, Starburst galaxies, Computational astronomy, Galactic bulge, Galaxy mergers, Galaxy evolution
Exploring the Impact of Galactic Interactions and Mergers on the Central Star Formation of APEX/EDGE-CALIFA Galaxies. Galactic interactions and subsequent mergers are a paramount channel for galaxy evolution. In this work, we use the data from 236 star-forming CALIFA galaxies with integrated molecular gas observations in their central region (approximately within an effective radius)-from the APEX millimeter telescope and the CARMA millimeter telescope array. This sample includes isolated (126 galaxies) and interacting galaxies in different merging stages (110 galaxies; from pairs, merging, and postmerger galaxies). We show that the impact of interactions and mergers in the center of galaxies is revealed as an increase in the fraction of molecular gas (compared to isolated galaxies). Furthermore, our results suggest that the change in star formation efficiency is the main driver for both an enhancement and/or suppression of the central star formation-except in merging galaxies where the enhanced star formation appears to be driven by an increase of molecular gas. We suggest that gravitational torques due to the interaction and subsequent merger transport cold molecular gas inwards, increasing the gas fraction without necessarily increasing star formation.

Keywords: Molecular gas, Galaxy interactions, Star formation
Continuous Gravitational Waves from Galactic Neutron Stars: Demography, Detectability, and Prospects. We study the prospects for the detection of continuous gravitational signals from normal Galactic neutron stars, i.e., nonrecycled stars. We use a synthetic population generated by evolving stellar remnants in time, according to several models. We consider the most recent constraints set by all-sky searches for continuous gravitational waves and use them for our detectability criteria. We discuss the detection prospects for the current and the next generation of gravitational-wave detectors. We find that neutron stars whose ellipticity is solely caused by magnetic deformations cannot produce any detectable signal, not even by third-generation detectors. The currently detectable sources all have B ≲ 1012 G and deformations that are not solely due to the magnetic field. For these, we find in fact that the larger the magnetic field, the higher the ellipticity required for the signal to be detectable, and this ellipticity is well above the value induced by the magnetic field. Third-generation detectors such as the Einstein Telescope and Cosmic Explorer will be able to detect up to ≈250 more sources than current detectors. We briefly treat the case of recycled neutron stars with a simplified model. We find that continuous gravitational waves from these objects will likely remain elusive to detection by current detectors, but should be detectable with the next generation of detectors.

Keywords: Neutron stars, Gravitational wave detectors, Stellar populations, Gravitational wave sources, Pulsars, Gravitational wave astronomy
Revealing the Gas Recycling in the Circumgalactic Medium (CGM) Utilizing a Luminous Lya Nebula around a Type II Quasar at z = 2.6 with the Keck Cosmic Web Imager (KCWI). How galaxies acquire material from the circumgalactic medium is a key question in galaxy evolution. Recent observations and simulations show that gas recycling could be an important avenue for star formation. This paper presents Keck Cosmic Web Imager integral field unit spectroscopic observations on a type II quasar, Q1517 + 0055 at z = 2.65, a pilot study of our Lyα nebulae sample at z ≈ 2. We revealed diffuse emission of the Lyα 1216, He II 1640, and C IV 1549 on the projected physical scale of 122, 45, and 79 kpc, respectively. The total Lyα luminosity is L Lyα  = 3.04 ± 0.02 × 1044 erg s-1. The line ratio diagnostics shows that He II/Lyα ≈ 0.08, and C IV/Lyα ≈ 0.28, consistent with the photoionization including recombination and photon pumping. We also identify the associated H I and C IV absorption from the spectra. By fitting the spectra, we derive both the column density and the velocity. We find that the velocity profile from both the absorption and the He II emission exhibit increasing trends. Moreover, both the line ratio diagnostic from the emission and the column density ratio from the absorption confirm that the cool gas metallicity is ≥Z ⊙. From detailed modeling and estimation, gas recycling might be a more plausible interpretation compared with the scenario of a powerful outflow.

Keywords: Quasars, High-redshift galaxies, Galaxy accretion, Circumgalactic medium
Main Sequence to Starburst Transitioning Galaxies: Gamma-Ray Burst Hosts at z   2. Star-forming galaxies populate a main sequence (MS), a well-defined relation between stellar mass (M *) and star formation rate (SFR). Starburst (SB) galaxies lie significantly above the relation, whereas quenched galaxies lie below the sequence. In order to study the evolution of galaxies on the SFR-M * plane and its connection to the gas content, we use the fact that recent episodes of star formation can be pinpointed by the existence of gamma-ray bursts (GRBs). Here we present sensitive [C I] nondetections of z ~ 2 ultraluminous infrared (ULIRG) GRB host galaxies. We find that our GRB hosts have similar molecular masses to those of other ULIRGs. However, unlike other ULIRGs, the GRB hosts are located at the MS or only a factor of a few above it. Hence, our GRB hosts are caught in the transition toward the SB phase. This is further supported by the estimated depletion times, which are similar to those of other transitioning galaxies. The GRB hosts are [C I]-dark galaxies, defined as having a [C I]/CO temperature brightness ratio of &lt;0.1. Such a low [C I]/CO ratio has been found in high-density environments (n H &gt; 104 cm-3) where CO is shielded from photodissociation, leading to underabundances of [C I]. This is consistent with the merger process that is indeed suggested for our GRB hosts by their morphologies.

Keywords: Starburst galaxies, Gamma-ray bursts, Quenched galaxies, Gamma-ray sources, Galaxies
Properties of Binary Systems in a One-dimensional Approximation. Evolutionary calculations for stars in close binary systems are in high demand to obtain better constraints on gravitational-wave source progenitors, understand transient events from stellar interactions, and more. Modern one-dimensional (1D) stellar codes make use of the Roche lobe radius R L concept in order to treat stars in binary systems. If the stellar companion is approaching its R L, mass transfer treatment is initiated. However, the effective acceleration also affects the evolution of a star in a close binary system. This is different from the gravity inside a single star, whether that single star is rotating or not. Here, we present numerically obtained tables of properties of stars in a binary system as a function of the effective potential: volume-equivalent radii of the equipotential surfaces, effective accelerations and the inverse effective accelerations averaged over the same equipotential surfaces, and the properties of the L 1-plane cross sections. The tables are obtained for binaries where the ratios of the primary star mass to the companion star mass are from 10-6 to 105 and include equipotential surfaces up to the star's outer Lagrangian point. We describe the numerical methods used to obtain these quantities and report how we verified the numerical results. We also describe and verify the method to obtain the effective acceleration for nonpoint mass distributions. We supply a sample code showing how to use our tables to get the average effective accelerations in 1D stellar codes.

Keywords: Roche lobe, Binary stars, Multiple star evolution, Lagrangian points, Stellar evolution
Very-high-energy Gamma-Ray Afterglows of GRB 201015A and GRB 201216C. Gamma-ray bursts (GRBs) 201015A and 201216C are valuable cases where very-high-energy (VHE) gamma-ray afterglows have been detected. By analyzing their prompt emission data, we find that GRB 201216C is an extremely energetic, long GRB with a hard gamma-ray spectrum, while GRB 201015A is a relative subenergetic, soft-spectrum GRB. Attributing their radio-optical-X-ray afterglows to the synchrotron radiation of the relativistic electrons accelerated in their jets, we fit their afterglow lightcurves with the standard external shock model and infer their VHE afterglows from the synchrotron self-Compton scattering process of the electrons. It is found that the jet of GRB 201015A is midrelativistic (Γ0 = 44), surrounded by a very dense medium (n = 1202 cm-3), and the jet of GRB 201216C is ultrarelativistic (Γ0 = 331), surrounded by a moderate dense medium (n = 5 cm-3). The inferred peak luminosity of the VHE gamma-ray afterglows of GRB 201216C is approximately 10-9 erg cm-2 s-1 at 57-600 s after the GRB trigger, making it detectable with the MAGIC telescopes at a high confidence level, even though the GRB is at a redshift of 1.1. Comparing their intrinsic VHE gamma-ray lightcurves and spectral energy distributions with GRBs 180720B, 190114C, and 190829A, we show that their intrinsic peak luminosity of VHE gamma-ray afterglows at 104 s after the GRB trigger is variable from 1045 to 5 × 1048 erg s-1, and their kinetic energy, initial Lorentz factor, and medium density are diverse among bursts.

Keywords: Gamma-ray bursts
Breakdown of the Newton-Einstein Standard Gravity at Low Acceleration in Internal Dynamics of Wide Binary Stars. A gravitational anomaly is found at weak gravitational acceleration g N ≲ 10-9 m s-2 from analyses of the dynamics of wide binary stars selected from the Gaia DR3 database that have accurate distances, proper motions, and reliably inferred stellar masses. Implicit high-order multiplicities are required and the multiplicity fraction is calibrated so that binary internal motions agree statistically with Newtonian dynamics at a high enough acceleration of ≈10-8 m s-2. The observed sky-projected motions and separation are deprojected to the 3D relative velocity v and separation r through a Monte Carlo method, and a statistical relation between the Newtonian acceleration g N ≡ GM/r 2 (where M is the total mass of the binary system) and a kinematic acceleration g ≡ v 2/r is compared with the corresponding relation predicted by Newtonian dynamics. The empirical acceleration relation at ≲10-9 m s-2 systematically deviates from the Newtonian expectation. A gravitational anomaly parameter δ obs-newt between the observed acceleration at g N and the Newtonian prediction is measured to be: δ obs-newt = 0.034 ± 0.007 and 0.109 ± 0.013 at g N ≈ 10-8.91 and 10-10.15 m s-2, from the main sample of 26,615 wide binaries within 200 pc. These two deviations in the same direction represent a 10σ significance. The deviation represents a direct evidence for the breakdown of standard gravity at weak acceleration. At g N = 10-10.15 m s-2, the observed to Newton-predicted acceleration ratio is ${g}_{\mathrm{obs}}/{g}_{\mathrm{pred}}={10}^{\sqrt{2}{\delta }_{\mathrm{obs}-\mathrm{newt}}}=1.43\pm 0.06$ . This systematic deviation agrees with the boost factor that the AQUAL theory predicts for kinematic accelerations in circular orbits under the Galactic external field.

Keywords: Gravitation, Non-standard theories of gravity, Binary stars, Modified Newtonian dynamics
Not So Fast, Not So Furious: Just Magnetic. WD 0810-353 is a white dwarf within the 20 pc volume around the Sun. Using Gaia astrometric distance and proper motions, and a radial velocity derived from Gaia spectroscopy, it has been predicted that this star will pass within 1 pc of the solar system in about 30 kyr. However, WD 0810-353 has been also shown to host a magnetic field with a strength of the order of 30 MG. Its spectrum is therefore not like those of normal DA stars of similar effective temperature. We have obtained and analyzed new polarized spectra of the star around Hα. Our analysis suggests that the visible surface of the star shows two regions of different field strength (~30 and ~45 MG, respectively), and opposite polarity. The spectra do not change over a 4 yr time span, meaning that either the stellar rotation period is no shorter than several decades, or that the field is symmetric about the rotation axis. Taking into account magnetic shift and splitting, we obtain an estimate of the radial velocity of the star (+83 ± 140 km s-1); we reject both the value and the claimed precision deduced from the Gaia DR3 spectroscopy (-373.7 ± 8.2 km s-1), and we conclude that there will probably be no close encounter between the solar system and WD 0810-353. We also reject the suggestion that the star is a hypervelocity runaway star, a survivor of a Type Ia supernova explosion. It is just a stellar remnant in the solar neighborhood with a very strong and complex magnetic field.

Keywords: Spectropolarimetry, White dwarf stars, Stellar magnetic fields, Solar neighborhood, Close encounters
FAST Reveals New Evidence for M94 as a Merger. We report the first high-sensitivity H I observation toward the spiral galaxy M94 with the Five-hundred-meter Aperture Spherical radio Telescope. From these observations, we discovered that M94 has a very extended H I disk, twice larger than that observed by THINGS, which is accompanied by a H I filament and seven high velocity clouds (HVCs) at different distances. The projected distances of these clouds and filaments are less than 50 kpc from the galactic center. We measured a total integrated flux (including all clouds/filament) of 127.3 ( ±1) Jy km s‑1, corresponding to a H I mass of (6.51 ± 0.06)×108 M ⊙ , which is 63.0% more than that observed by THINGS. By comparing numerical simulations with the H I maps and the optical morphology of M94, we suggest that M94 is likely a remnant of a major merger of two galaxies, and the HVCs and H I filament could be the tidal features that originated from the first collision of the merger, which happened about 5 Gyr ago. Furthermore, we found a seemingly isolated H I cloud at a projection distance of 109 kpc without any optical counterpart detected. We discuss the possibilities of the origin of this cloud, such as dark dwarf galaxy and RELHIC (REionization-Limited H I Cloud). Our results demonstrate that high-sensitivity and wide-field H I imaging is important in revealing diffuse cold gas structures and tidal debris, which is crucial to understand the dynamical evolution of galaxies.

Keywords: Galaxy dynamics, Galaxy interactions, Galaxy kinematics, Galaxy evolution, H I regions
Magnetic Activity Evolution of Solar-like Stars. I. S <SUB>ph</SUB>-Age Relation Derived from Kepler Observations. The ages of solar-like stars have been at the center of many studies such as exoplanet characterization or Galactic-archeology. While ages are usually computed from stellar evolution models, relations linking ages to other stellar properties, such as rotation and magnetic activity, have been investigated. With the large catalog of 55,232 rotation periods, P rot, and photometric magnetic activity index, S ph from Kepler data, we have the opportunity to look for such magneto-gyro-chronology relations. Stellar ages are obtained with two stellar evolution codes that include treatment of angular momentum evolution, hence using P rot as input in addition to classical atmospheric parameters. We explore two different ways of predicting stellar ages on three subsamples with spectroscopic observations: solar analogs, late-F and G dwarfs, and K dwarfs. We first perform a Bayesian analysis to derive relations between S ph and ages between 1 and 5 Gyr, and other stellar properties. For late-F and G dwarfs, and K dwarfs, the multivariate regression favors the model with P rot and S ph with median differences of 0.1% and 0.2%, respectively. We also apply Machine Learning techniques with a Random Forest algorithm to predict ages up to 14 Gyr with the same set of input parameters. For late-F, G and K dwarfs together, predicted ages are on average within 5.3% of the model ages and improve to 3.1% when including P rot. These are very promising results for a quick age estimation for solar-like stars with photometric observations, especially with current and future space missions.

Keywords: Stellar rotation, Asteroseismology, Stellar ages, Magnetic variable stars
On the Formation of Vinylamine (C<SUB>2</SUB>H<SUB>3</SUB>NH<SUB>2</SUB>) in Interstellar Ice Analogs. Amines-organic molecules carrying the -NH2 moiety-have been recognized as a vital intermediate in the formation of prebiotic molecules such as amino acids and nucleobases. Here we report the formation of vinylamine (C2H3NH2), which was recently detected toward G+0.693-0.027, in interstellar ice analogs composed of acetylene (C2H2) and ammonia (NH3) exposed to energetic electrons. Our experiments mimic cascades of secondary electrons in the tracks of galactic cosmic rays impinging on interstellar ice in molecular clouds. Tunable photoionization reflectron time-of-flight mass spectrometry (PI-Re-TOF-MS), along with isomer-specific assignments, reveals the production of vinylamine (C2H3NH2). Quantum chemical computations suggest that both a radical-radical recombination of the amino (NH2) with the vinyl (C2H3) radical and a one-step concerted route are feasible pathways to vinylamine (C2H3NH2). The results present the first documented route to form vinylamine in interstellar ice analogs. This unsaturated amine, which is isovalent to vinylalcohol (C2H3OH), could be a key precursor for the abiotic synthesis of prebiotic molecules such as amino acids and nucleobases, with implications for the origins-of-life theme.

Keywords: Interstellar medium, Laboratory astrophysics, Pre-biotic astrochemistry, Astrochemistry