Sazuna/UAT_keywords huggingface dataset:
Star‑Disk Collisions: Implications for Quasi-periodic Eruptions and Other Transients near Supermassive Black Holes. We use Athena++ to study the hydrodynamics of repeated star‑accretion disk collisions close to supermassive black holes, and we discuss their implications for the origin of quasi-periodic eruptions (QPEs) and other repeating nuclear transients. We quantify the impact of the collisions on the stellar structure, the amount of stripped stellar debris, and the orbital properties of the debris. We provide simple fitting functions for the stellar mass loss per collision; the mass loss is much larger after repeated collisions, due to the dilute stellar atmosphere shock-heated in earlier collisions. The lifetime of the QPE-emitting phase set by stellar mass loss in star‑disk collision models for QPEs is thus at most ∼1000 yr; it is shortest for eRO-QPE2, of order a few decades. The mass of the stripped stellar debris per collision and its orbital properties imply that currently observed QPEs are not powered by direct star‑disk collisions but rather by collisions between the stellar debris liberated in previous collisions and the accretion disk ("circularization shocks"). We discuss how the hydrodynamics of this interaction can explain the diverse timing properties of QPEs, including the regular timing of GSN 069 and eRO-QPE2 and the large flare-to-flare timing variations observed in eRO-QPE1. QPEs with recurrence times of many days, if observed, may have more regular timing.

Keywords: X-ray transient sources, Supermassive black holes, Tidal disruption, Stellar dynamics
UNCOVER: Candidate Red Active Galactic Nuclei at 3 &lt; z &lt; 7 with JWST and ALMA. The James Webb Space Telescope (JWST) is revolutionizing our knowledge of z &gt; 5 galaxies and their actively accreting black holes. Using the JWST Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) in the lensing field A2744, we report the identification of a sample of little red dots at 3 &lt; z phot &lt; 7 that likely contain highly reddened accreting supermassive black holes. Using a NIRCam-only selection to F444W &lt; 27.7 mag, we find 26 sources over the ∼45 arcmin2 field that are blue in F115W ‑ F200W ∼ 0 (or β UV ∼ –2.0 for f  λ  ∝ λ  β ), red in F200W ‑ F444W = 1‑4 (β opt ∼ +2.0), and are dominated by a point-source-like central component. Of the 20 sources with deep Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm coverage, none are detected individually or in a stack. For the majority of the sample, spectral energy distribution fits to the JWST+ALMA observations prefer models with hot dust rather than obscured star formation to reproduce the red NIRCam colors and ALMA 1.2 mm nondetections. While compact dusty star formation cannot be ruled out, the combination of extremely small sizes (&lt;r  e &gt; ≈ 50 pc after correction for magnification), red rest-frame optical slopes, and hot dust can be explained by reddened broad-line active galactic nuclei (AGNs). Our targets have faint M 1450 ≈ ‑14 to ‑18 mag but inferred bolometric luminosities of L bol = 1043–1046 erg s‑1, reflecting their obscured nature. If the candidates are confirmed as AGNs with upcoming UNCOVER spectroscopy, then we have found an abundant population of reddened luminous AGNs that are at least ten times more numerous than UV-luminous AGNs at the same intrinsic bolometric luminosity.

Keywords: AGN host galaxies, Galaxies
The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615. We use Hubble Space Telescope imaging to study the globular cluster system of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. We select globular cluster candidates through a combination of size and color, while simultaneously rejecting contamination from background galaxies that would be unresolved in ground-based imaging. Our sample of globular cluster candidates is essentially complete down to a limiting magnitude of F814W = 24.0, ≈90% down the globular cluster luminosity function (GCLF). We estimate a total globular cluster population for VCC 615 of  , resulting in a specific frequency of  , quite high compared to normal galaxies of similar luminosity, but consistent with the large specific frequencies found in some other UDGs. The abundant cluster population suggests the galaxy is enshrouded by a massive dark halo, consistent with previous dynamical mass estimates using globular cluster kinematics. While the peak of the GCLF appears slightly brighter than expected (by ≈0.3–0.5 mag), this difference is comparable to the 0.3 mag uncertainty in the measurement, and we see no sign of an extremely luminous population of clusters similar to those detected in the UDGs NGC1054-DF2 and -DF4. However, we do find a relatively high fraction ( %) of large clusters with half-light radii Rh &gt; 9 pc. The galaxy's offset nucleus appears photometrically distinct from the globular clusters, and is more akin to ultracompact dwarfs (UCDs) in Virgo. Over time, VCC615's already diffuse stellar body may be further stripped by cluster tides, leaving the nucleus intact to form a new Virgo UCD.

Keywords: Galaxy clusters, Globular star clusters, Dwarf galaxies, Galaxy evolution, Low surface brightness galaxies
Conditions for Solar Prominence Formation Triggered by Single Localized Heating. We performed numerical simulations to study mechanisms of solar prominence formation triggered by a single heating event. In the widely accepted "chromospheric-evaporation condensation" model, localized heating at footpoints of a coronal loop drives plasma evaporation and eventually triggers condensation. The occurrence of condensation is strongly influenced by the characteristics of the heating. Various theoretical studies have been conducted along one-dimensional field lines with quasi-steady localized heating. The quasi-steady heating is regarded as the collection of multiple heating events among multiple strands constituting a coronal loop. However, it is reasonable to consider a single heating event along a single field line as an elemental unit. We investigated the condensation phenomenon triggered by a single heating event using 1.5-dimensional magnetohydrodynamic simulations. By varying the magnitude of the localized heating rate, we explored the conditions necessary for condensation. We found that, when a heating rate approximately ~104 times greater than that of steady heating was applied, condensation occurred. Condensation was observed when the thermal conduction efficiency in the loop became lower than the cooling efficiency, with the cooling rate significantly exceeding the heating rate. Using the loop length L and the Field length λF, the condition for condensation is expressed as λF ≲ L/2 under conditions where cooling exceeds heating. We extended the analytically derived condition for thermal nonequilibrium to a formulation based on heating amount.

Keywords: Magnetohydrodynamics, Solar prominences, Solar corona
Marginal Role of the Electrostatic Instability in the GeV-scale Cascade Flux from 1ES 0229+200. Relativistic pair beams produced in the intergalactic medium by TeV gamma rays from blazars are expected to generate a detectable GeV-scale electromagnetic cascade, yet this cascade is absent in the observed spectra of hard-spectrum TeV emitting blazars. This suppression is often attributed to weak intergalactic magnetic fields (IGMF) deflecting electron-positron pairs out of the line of sight. Alternatively, it has been proposed that beam-plasma instabilities could drain the energy of the beam before they produce the secondary cascades. Recent studies suggest that the modification of beam distribution due to these instabilities is primarily driven by particle scattering, rather than energy loss. In this paper, we quantitatively assess, for the blazar 1ES 0229+200, the arrival time of secondary gamma rays at Earth from the beam scattering by the electrostatic instability. We first computed the production rates of electron-positron pairs at various distances using the Monte Carlo simulation CRPropa. We then simulated the feedback of the plasma instability on the beam, incorporating production rates and inverse Compton cooling, to determine the steady-state distribution function. Our findings reveal that the time delay of the GeV secondary cascade arrival due to instability broadening is on the order of a few months. This delay is insufficient to account for the missing cascade emission in blazar spectra, suggesting that plasma instabilities do not significantly affect IGMF constraints.

Keywords: Blazars, Gamma-rays
RAMSES-yOMP: Performance Optimizations for the Astrophysical Hydrodynamic Simulation Code RAMSES. Developing an efficient code for large, multiscale astrophysical simulations is crucial in preparing for the upcoming era of exascale computing. RAMSES is an astrophysical simulation code that employs parallel processing based on the message-passing interface (MPI). However, it has limitations in computational and memory efficiency when using a large number of CPU cores. The problem stems from inefficiencies in workload distribution and memory allocation that inevitably occur when a volume is simply decomposed into domains equal to the number of working processors. We present RAMSES-yOMP, which is a modified version of RAMSES designed to improve parallel scalability. Major updates include the incorporation of open multiprocessing into the MPI parallelization to take advantage of both the shared and distributed memory models. Utilizing this hybrid parallelism in high-resolution benchmark simulations with full prescriptions for baryonic physics, we achieved an increase in performance by a factor of 2 in the total run-time, while using 75% less memory and 30% less storage than the original code, when using the same number of processors. These improvements allow us to perform larger or higher-resolution simulations than what was feasible previously.

Keywords: Computational astronomy, Galaxy evolution, Astronomy software, Computational methods
Transiting Jupiters around M Dwarfs Have Similar Masses to FGK Warm Jupiters. This paper presents a comparative analysis of the bulk properties (mass and radius) of transiting giant planets (≳8R⊕) orbiting FGKM stars. Our findings suggest that the average mass of M-dwarf Jupiters is lower than that of their solar-type counterparts, primarily due to the scarcity of super-Jupiters (≳2 MJ) around M dwarfs. However, when super-Jupiters are excluded from the analysis, we observe a striking similarity in the average masses of M-dwarf and FGK warm-Jupiters. We propose that these trends can be explained by a minimum disk dust mass threshold required for Jovian formation through core accretion, which is likely to be satisfied more often around higher-mass stars. This simplistic explanation suggests that the disk mass has more of an influence on giant planet formation than other factors, such as the host star mass, formation location, metallicity, radiation environment, etc., and also accounts for the lower occurrence of giant planets around M-dwarf stars. Additionally, we explore the possibility of an abrupt transition in the ratio of super-Jupiters to Jupiters around F-type stars at the Kraft break, which could be a product of vsini-related detection biases, but requires additional data from an unbiased sample with published nondetections to confirm. Overall, our results provide valuable insights into the formation and evolution of giant exoplanets across a diverse range of stellar environments.

Keywords: M dwarf stars, Exoplanet formation, Extrasolar gaseous giant planets, Astrostatistics
No Evidence for a Significant Evolution of M<SUB>•</SUB>–M. Relation in Massive Galaxies up to z ∼ 4. Over the past two decades, tight correlations between black hole masses (M•) and their host galaxy properties have been firmly established for massive galaxies (with stellar mass  log(M*/M⊙)≳10 ) at low-z (z &lt; 1), indicating coevolution of supermassive black holes and galaxies. However, the situation at high-z, especially beyond cosmic noon (z ≳ 2.5), is controversial. With a combination of JWST Near Infrared Camera (NIRCam)/wide field slitless spectroscopy (WFSS) from FRESCO, CONGRESS and deep multiband NIRCam/image data from JADES in the GOODS fields, we study the black-hole-to-galaxy mass relation at z ∼ 1–4. After identifying 18 broad-line active galactic nuclei (AGNs) at 1 &lt; z &lt; 4 (with 8 at z &gt; 2.5) from the WFSS data, we measure their black hole masses based on broad near-infrared lines (Paα, Paβ, and He I λ10833 Å), and constrain their stellar masses from AGN-galaxy image decomposition or spectral energy distribution decomposition. Taking account of the observational biases, the intrinsic scatter of the M•‑M* relation, and the errors in mass measurements, we find no significant difference in the M•/M* ratio for 2.5 &lt; z &lt; 4 compared to that at lower redshifts (1 &lt; z &lt; 2.5), suggesting no evolution of the M•‑M* relation at  log(M*/M⊙)≳10  up to z ∼ 4.

Keywords: Supermassive black holes, Active galaxies, Active galactic nuclei, Galaxy evolution
Thorium in Kilonova Spectra: Exploring the Heaviest Detectable Element. Kilonova spectra provide us with direct information about rapid neutron-capture nucleosynthesis (r-process) in neutron star (NS) mergers. In this paper, we study the signatures of elements beyond the third r-process peak expected to be produced in neutron-rich ejecta in the photospheric spectra of kilonova. We select Ra II, Ac III, and Th III as our candidates because they have a small number of valence electrons and low-lying energy levels, which tend to result in strong absorption features. We systematically calculate the strength of bound–bound transitions of these candidates by constructing a line list based on the available atomic database. We find that Th III is the most promising species, showing strong transitions at near-infrared wavelengths. By performing radiative transfer simulations, we find that Th III produces broad absorption features at ∼18000 Å in the spectra when the mass ratio of actinides to lanthanides is larger than the solar r-process ratio and the mass fraction of lanthanides is ≲6 × 10‑4. Our models demonstrate that the Th feature may be detectable if the bulk of the ejecta in the line-forming region is dominated by relatively light r-process elements with the mixture of a small fraction of very neutron-rich material. Such conditions may be realized in the mergers of unequal-mass NSs or black hole–NS binaries. To detect the Th absorption features, observations from space (such as with the JWST) or high-altitude sites are important as the wavelength region of the Th features overlaps with that affected by strong telluric absorption.

Keywords: Radiative transfer simulations, R-process, Transient sources, Atomic physics
Multiwavelength Properties of Infrared-faint Radio Sources Based on Analysis of Their Spectral Energy Distribution. Infrared-faint radio sources (IFRSs) are believed to be a rare class of radio-loud active galactic nuclei (AGNs) characterized by their high radio-to-infrared flux density ratios of up to several thousand. Previous studies have shown that a fraction of IFRSs are likely to be hosted in dust-obscured galaxies. In this paper, our aim is to probe the dust properties, star formation rate (SFR), and AGN activity of IFRSs by modeling the UV-to-infrared spectral energy distribution (SED) of 20 IFRSs with spectroscopic redshifts ranging from 1.2 to 3.7. We compare the Bayesian evidence of a three-component model (stellar, AGN, and cold dust) with that of a two-component model (stellar and cold dust) for six IFRSs in our sample with far-infrared photometry and find that the three-component model has significantly higher Bayesian evidence, suggesting that IFRSs are most likely to be AGNs. The median SED of our IFRS sample shows similarities to an AGN–starburst composite in the IR regime. The derived IR luminosities of IFRSs indicate that they are low-luminosity counterparts of high-redshift radio galaxies. We disentangle the contributions of AGN-heated and star formation-heated dust to the IR luminosity of IFRSs and find that our sample is likely AGN-dominated. However, despite the evidence for significant impact of an AGN on the host galaxy, the AGN luminosity of our sample does not show correlation with the SFR of the sources.

Keywords: Active galaxies, Active galactic nuclei, Radio galaxies
HETDEX-LOFAR Spectroscopic Redshift Catalog. We combine the power of blind integral field spectroscopy from the Hobby–Eberly Telescope (HET) Dark Energy Experiment (HETDEX) with sources detected by the Low Frequency Array (LOFAR) to construct the HETDEX-LOFAR Spectroscopic Redshift Catalog. Starting from the first data release of the LOFAR Two-metre Sky Survey, including a value-added catalog with photometric redshifts, we extracted 28,705 HETDEX spectra. Using an automatic classifying algorithm, we assigned each object a star, galaxy, or quasar label along with a velocity/redshift, with supplemental classifications coming from the continuum and emission-line catalogs of the internal, fourth data release from HETDEX (HDR4). We measured 9087 new redshifts; in combination with the value-added catalog, our final spectroscopic redshift sample is 9710 sources. This new catalog contains the highest substantial fraction of LOFAR galaxies with spectroscopic redshift information; it improves archival spectroscopic redshifts and facilitates research to determine the [O II] emission properties of radio galaxies from 0.0 &lt; z &lt; 0.5, and the Lyα emission characteristics of both radio galaxies and quasars from 1.9 &lt; z &lt; 3.5. Additionally, by combining the unique properties of LOFAR and HETDEX, we are able to measure star formation rates (SFRs) and stellar masses. Using the Visible Integral-field Replicable Unit Spectrograph, we measure the emission lines of [O III], [Ne III], and [O II] and evaluate line-ratio diagnostics to determine whether the emission from these galaxies is dominated by active galactic nuclei or star formation and fit a new SFR–L 150MHz relationship. ∗Based on observations obtained with the Hobby–Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Keywords: Galaxy evolution, Radio active galactic nuclei, Redshift surveys, Radio continuum emission
A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4. High-z radio galaxies (HzRGs) are considered important objects for understanding the formation and evolution of massive galaxies in the early Universe. However, until to date, detailed studies of the stellar population of HzRGs, such as the star formation history, have been scarce. Therefore, this study conducted a new survey to establish a less-biased sample of HzRGs and consequently investigate their properties. We utilized a sample of g-dropout Lyman break galaxies (LBGs) obtained from an optical wide and deep imaging survey made by Subaru Hyper Suprime-Cam. Based on the cross matching of this LBG sample with the Very Large Array Faint Images of the Radio Sky at Twenty cm radio survey data, we constructed a photometric sample of HzRGs at z ∼ 4 for a ∼560 deg2 survey field. Consequently, we identified 146 HzRG candidates. To analyze the characteristics of these candidates, we focus on objects exhibiting the near-infrared photometry of VIKING or UKIRT Infrared Deep Sky Survey and the mid-infrared photometry of unWISE (28 objects). The results indicate that seven objects exhibit spectral energy distributions (SEDs) consistent with galaxies at z ∼ 4. The HzRG candidates have very large stellar masses with ∼4.2 × 1011 M ⊙ on average. This stellar mass is similar to that of previously discovered ultra-steep-spectrum HzRGs at z ∼ 4, though our sample is affected by a sample selection bias that selects only HzRGs with M ⋆ &gt; 1011 M ⊙. Further, the SEDs of those HzRG candidates suggest a past fast quenching with a rough timescale of ∼0.1 Gyr, as evidenced from the rest-frame UVJ diagram.

Keywords: Galaxy evolution
Warped Accretion Disks and Quasars with Episodic Periodicity of Long-term Variations. It has been found from long-term monitoring campaigns that some quasars are undergoing quasiperiodic variations (most of them with damped amplitudes) in optical bands, but how to explain the origin of such light-curve variations still remains an open question. In this paper, we use the warped accretion disks model to explain the quasiperiodical variations. This model employs a free-bending wave traveling in an accretion disk, which causes the orientation of the central part of the disk to oscillate from the line of sight, resulting in a quasiperiodical variation. We numerically solve the governing equation of warp propagation and calculate the simulated R-band light curves, finding that the periodical light curves generated by this model have damped amplitudes. To compare with observations, we select SDSSJ134820.42+194831.5 as a preliminary example from a sample of periodic quasar candidates by combining CRTS with other public survey data and fitting its light curve with different observational angles. Our result gives a reduced χ 2 ≃ 2.4, implying that the model might give insights into the future application of the warped disk model.

Keywords: Supermassive black holes, Active galactic nuclei, Quasars
Constraining the Binarity of Massive Black Holes in the Galactic Center and Some Nearby Galaxies via Pulsar Timing Array Observations of Gravitational Waves. Massive black holes (MBHs) exist in the Galactic center (GC) and other nearby galactic nuclei. As a natural outcome of galaxy mergers, some MBHs may have a black hole (BH) companion. In this paper, assuming that the MBHs in the GC and some nearby galaxies are in binaries with orbital periods ranging from months to years (gravitational-wave frequency ∼1–100 nHz), we investigate the detectability of gravitational waves from these binary MBHs (BBHs) and constraints on the parameter space for the existence of BBHs in the GC, Large Magellanic Cloud (LMC), M31, M32, and M87 that may be obtained by current/future pulsar timing array (PTA) observations. We find that a BBH in the GC, if any, can be revealed by the Square Kilometre Array PTA (SKA-PTA) if it has mass ratio q ≳ 10‑4–10‑3 and semimajor axis a ∼ 20–103 au. The existence of a BH companion of the MBH can be revealed by SKA-PTA with ∼20 yr observations in M31 if q ≳ 10‑4 and a ∼ 102–104 au or in M87 if q ≳ 10‑5 and a ∼ 103–2 × 104 au, but not in the LMC and M32 if q ≪ 1. If a number of millisecond stable pulsars with distances ≲0.1–1 pc away from the central MBH in the GC, the LMC, M32, or M31 can be detected in future and applied to PTAs, a BH companion with mass even down to ∼100 M ⊙, close to stellar masses, can be revealed by such PTAs. Future PTAs are expected to provide an independent way to reveal BBHs and low-mass MBH companions in the GC and nearby galaxies, improving our understandings of the formation and evolution of MBHs and galaxies.

Keywords: Black hole physics, Supermassive black holes, Galactic center, Pulsars, Gravitational waves, Andromeda Galaxy, Magellanic Clouds