Sazuna/UAT_keywords huggingface dataset:
Enhanced Gas-phase Metallicities and Suppressed Outflows for Galaxies in a Rich Cluster Core at Cosmic Noon. We present the results of near-infrared spectroscopy using Keck/MOSFIRE for 23 member galaxies in the X-ray cluster XCS 2215 (z = 1.46) to investigate the environmental dependence of gaseous flows and metallicities. We find that the metallicities derived from Hα and [N II] emission lines of the cluster galaxies are enhanced by 0.08─0.15 dex with ∼2σ significance compared to field counterparts for the same stellar mass. This suggests that inefficient gas accretion in the shock-heated intracluster medium (ICM) in the cluster core results in the lack of metallicity dilution. We also estimate the mass-loading factor by comparing the observed galaxies with the chemical evolution model that takes into account the outflow processes on the metallicity-versus-gas mass fraction diagram constructed together with the Atacama Large Millimeter/submillimeter Array data. We find that the outflows from galaxies in the cluster core region tend to be weaker than those of galaxies in the general field. It is likely due to the confinement of gas by the high pressure of the surrounding ICM in the cluster core, which leads to the recycling of the outflowing gas that comes back to the system and is used for further star formation, resulting in the progression of chemical evolution. Compared with higher-redshift protocluster galaxies at z &gt; 2, which tend to show lower metallicity than the field galaxies due probably to dilution of metals by pristine gas inflow, we are seeing the transition of the gas accretion mode from the efficient cold stream mode to the inefficient hot mode.

Keywords: Galaxy clusters, High-redshift galaxies, Galaxy evolution, Interstellar medium
The Radio Flare and Multiwavelength Afterglow of the Short GRB 231117A: Energy Injection from a Violent Shell Collision. We present the early radio detection and multiwavelength modeling of the short gamma-ray burst (GRB) 231117A at redshift z = 0.257. The Australia Telescope Compact Array automatically triggered a 9 hr observation of GRB 231117A at 5.5 and 9 GHz following its detection by the Neil Gehrels Swift Observatory just 1.3 hr post-burst. Splitting this observation into 1 hr time bins, the early radio afterglow exhibited flaring, scintillating and plateau phases. The scintillation allowed us to place the earliest upper limit (&lt;10 hr) on the size of a GRB blast wave to date, constraining it to &lt;1 × 1016 cm. Multiwavelength modeling of the full afterglow required a period of significant energy injection between ∼0.02 and 1 day. The energy injection was modeled as a violent collision of two shells: a reverse shock passing through the injection shell explains the early radio plateau, while an X-ray flare is consistent with a shock passing through the leading impulsive shell. Beyond 1 day, the blast wave evolves as a classic decelerating forward shock with an electron distribution index of p = 1.66 ± 0.01. Our model also indicates a jet break at ∼2 days, and a half-opening angle of  θj=16.°6±1.°1 . Following the period of injection, the total energy is ζ ∼ 18 times the initial impulsive energy, with a final collimation-corrected energy of EKf ∼ 5.7 × 1049 erg. The minimum Lorentz factors this model requires are consistent with constraints from the early radio measurements of Γ &gt; 35 to Γ &gt; 5 between ∼0.1 and 1 day. These results demonstrate the importance of rapid and sensitive radio follow-up of GRBs for exploring their central engines and outflow behaviour.

Keywords: Gamma-ray bursts, Transient sources, X-ray transient sources, Gamma-ray transient sources, Radio transient sources
Quasiperiodic Fast-propagating Waves Driven by the Tuning-fork Effect during Magnetic Reconnection. Through three-dimensional MHD simulations, we have uncovered a kind of fast coronal wave originating from both ends of a current sheet (CS) during a solar eruption. These waves are observed to appear near the top and bottom ends of the reconnection-related CS. The simulations demonstrate the presence of termination shock regions above the two ends of the CS. As the reconnection outflows escape from the vertical CS and encounter these termination shocks, they undergo partial reflection, redirecting toward the CS terminal fork walls. The identified waves propagate rapidly at a speed of approximately 1400 km s−1 with a period of just 2 s. Concurrently, the time evolution of intensity within a small region of the CS terminal fork structures exhibits a similar oscillation period of 2 s. All this evidence supports the notion that these quasiperiodic fast-propagating (QFP) waves were excited by tuning-fork effects within the CS system. Essentially, the rapid reconnection outflows are reflected by the terminal shocks, striking the fork walls at the CS ends. Moreover, parts of the oscillations along the tuning-fork handle are transformed into thermal energy, accumulating in the CS center and elevating the temperature. This is the first time to report such QFP waves resulting from tuning-fork effects within the CS during a solar eruption. These waves are anticipated to manifest closely following the propagation of CMEs and adjacent to the related postflare loops in observations, with partial confirmation in current observations.

Keywords: Magnetohydrodynamics, Solar coronal waves, Solar prominences
Attributing the O'Connell Effect in Contact Binaries to a Cooling Mass-transfer Stream. Contact binaries are very short-period systems that are continuously interacting by transferring mass and energy. Obtaining large, statistical samples of contact binaries from photometric surveys can put valuable constraints on the various processes involved in their evolution. Modeling those systems, however, presents some challenges. In some contact-binary light curves, the O'Connell effect is visible, where the maxima at both quarter phases are unequal. In the literature, this effect is typically attributed to magnetic spots on the surface of the binary. In this work, we model contact-binary surfaces using PHOEBE and include a parametric prescription for a lateral mass- and energy-transfer stream that travels from the hotter primary to the cooler secondary. We allow this stream to have a variable heat capacity. We fit a system from the Kepler sample with a strong O'Connell effect and show that a low-heat capacity stream can explain the unequal maxima. This suggests that, in such systems, surface flows can play a significant role in transferring heat between components. Our methods can be used on larger samples of contact binaries from the Optical Gravitational Lensing Experiment, Kepler, or TESS to advance our understanding of contact binary structure and evolution.

Keywords: Light curves, Binary stars, Contact binary stars
SpiderCat: A Catalog of Compact Binary Millisecond Pulsars. We present SpiderCat, a multiwavelength catalog of all publicly known compact binary millisecond pulsars (MSPs) in the Galactic field. These systems, colloquially known as "spiders," consist of neutron stars in tight orbits with low-mass companions, which are gradually ablated by the pulsar wind. SpiderCat includes both primary subclasses—redbacks and black widows—distinguished by companion mass, as well as candidates and peculiar systems such as transitional, huntsman, and tidarren MSPs. As of this initial release, SpiderCat contains 111 entries: 30 redbacks, 50 black widows, two huntsmans, 23 redback candidates, five black widow candidates, and one huntsman candidate. In this paper, we compile and summarize key parameters for each system, including spin and orbital properties, and multiwavelength data from radio, optical, X-ray, and γ-ray observations. An interactive, publicly accessible web interface, at https://astro.phys.ntnu.no/SpiderCAT, enables exploration and visualization of the data. The rapid growth of the number of known spiders, accelerated by the Fermi Large Area Telescope survey and its ability to identify MSPs in γ rays, has opened the door to population-level studies. Utilizing SpiderCat, we analyze trends in spin period, orbital period, companion mass, emission properties, and spatial distribution. SpiderCat serves as a dynamic, multiwavelength repository for this unique class of binary pulsars, facilitating new discoveries and constraints on pulsar evolution, particle acceleration, and the neutron star equation of state.

Keywords: Neutron stars, Low-mass x-ray binary stars, Millisecond pulsars
Misaligned External Gas Acquisition Boosts Central Black Hole Activities. One important question in active galactic nuclei (AGN) is how gas is brought down to the galaxy center. Both internal secular evolution (torque induced by nonaxisymmetric galactic structures such as bars) and external processes (e.g., mergers or interactions) are expected to redistribute the angular momentum (AM) and transport gas inward. However, it is still under debate whether these processes can significantly affect AGN activities. Here we for the first time report that AGN fraction increases with the difference of kinematic position angles (∆PA ≡ ∣PAgas − PAstar∣) between ionized gas (PAgas) and stellar disks (PAstar) in blue and green galaxies, meanwhile this fraction remains roughly constant for red galaxies. Also, the high luminosity AGN fraction increases with ∆PA, while the low luminosity AGN fraction is independent of ∆PA. These observational results support a scenario in which the interaction between accreted and preexisting gas provides the AM loss mechanism, thereby the gas inflow fuels the central BH activities, and the AM loss efficiency is positively correlated with the ∆PA.

Keywords: Active galactic nuclei, Galaxy kinematics, Galaxy evolution
Identification and Modeling of Optically Thin Inverse Compton Scattering in the Prompt Emission of GRB 131014A. The mechanism responsible for the prompt gamma-ray emission of a gamma-ray burst (GRB) continues to remain an enigma. The detailed analysis of the spectrum of GRB 131014A observed by the Fermi Gamma-ray Burst Monitor and Large Area Telescope has revealed an unconventional spectral shape that significantly deviates from the typical Band function. The spectrum exhibits three distinctive breaks and an extended power law at higher energies. Furthermore, the lower end of the spectrum aligns with power-law indices greater than −0.5, and in the brightest region of the burst, these values approach +1. The lowest spectral break is thereby found to be consistent with a blackbody. These observed spectral characteristics strongly suggest the radiation process to be inverse Compton scattering (ICS) in an optically thin region. Applying the empirical fit parameters for physical modeling, we find that the kinetic energy of the GRB jet of bulk Lorentz factor, Γ ∼ 400, gets dissipated just above the photosphere, approximately at a radius of ∼1014 cm. The electrons involved in this process are accelerated to a power-law index of δ = −1.5, and the minimum electron Lorentz factor,  γmin , is approximately 3. In summary, this study provides a comprehensive identification and detailed modeling of optically thin ICS in the prompt emission of GRB 131014A.

Keywords: Gamma-ray bursts, Non-thermal radiation sources, High energy astrophysics
An Insight-HXMT View of the Evolution of the Type-C Quasiperiodic Oscillation during the Flaring State of Swift J1727.8─1613. We present a detailed analysis of the evolution of type-C quasiperiodic oscillations (QPOs) observed during the flaring state of the recently discovered black hole X-ray binary Swift J1727.8─1613, utilizing data from the Insight Hard X-ray Modulation Telescope. By examining the relation between the QPO fractional rms amplitude and QPO frequency across various energy bands, we discover that the behavior significantly differs between these energy bands. Below 10 keV, the QPO fractional rms generally decreases with increasing QPO frequency, whereas above 10 keV, the QPO fractional rms remains relatively stable with frequency. Additionally, we report, for the first time, the detection of a common break at around 4 Hz in the relation between QPO fractional rms and frequency in both the 2─4 and 50─100 keV energy bands. We also find that the evolution of all the spectral parameters alters its behavior at around 4 Hz, with the changes in all parameters becoming flatter. This suggests a significant change in the geometry of the accretion flow. We attribute the observed break to the overall changes in the spectrum.

Keywords: Low-mass x-ray binary stars, Accretion, Stellar mass black holes, Astrophysical black holes
84 and 169 s Rotation of Two Isolated, Ultramassive, Strongly Magnetic White Dwarfs. Photometric variability in massive, magnetic white dwarfs (WDs) on the timescales of less than a few hours is oft interpreted as being due to magnetic spots on the surface of a rotating star. Increasing numbers of these short period variables are being discovered with the continued growth of time-domain astronomy, testing theories of magnetic WD formation and angular momentum evolution. We present the detection of extremely rapid rotation in the WDs SDSS J1557+0411 and PG 1312+099, with periods of 168.94 and 83.72 s, respectively. We consider other possible causes of the monoperiodic photometric variability, including binarity (eclipses and ellipsoidal variations) and asteroseismic pulsations. Though these cannot be ruled out with the existing data, these alternative explanations seem unlikely. SDSS J1557+0411 was predicted to be a rapidly rotating oxygen─neon core WD by M. E. Camisassa et al., a prediction borne out at least in part by our observations. PG 1312+099 was previously observed via polarimetry to be rotating with a period of ∼5.4 hr; we propose that this object may be an unresolved double degenerate system.

Keywords: Starspots, White dwarf stars, Light curves, Stellar magnetic fields, Short period variable stars, Stellar rotation
A Gravitational Millilensing Candidate in GRB 111012A with a Possible Compact Merger Origin. We identify GRB 111012A in the Fermi Gamma-ray Burst Monitor archive as a candidate case of gravitational millilensing. The burst shows two pulses separated by ∼3.1 s, reminiscent of previously reported lensed events such as GRB 950830 and GRB 200716C. The temporal profiles of the two pulses are highly consistent: autocorrelation analysis indicates similarity at a significance level above 4σ, and a chi-squared comparison supports the hypothesis that they arise from the same underlying distribution. Additionally, their spectra are consistent within 3σ uncertainties. Although the overall duration of ∼8 s is longer than typical short bursts, the spectral lag and minimum variability timescales are consistent with those of short gamma-ray bursts. Interpreting the delay and flux ratio as a lensing signature implies a redshifted lensing mass 1.27( ± 0.12) × 105 M⊙, consistent with an intermediate-mass black hole. However, the discrepancy in the hardness ratio might be caused by the structured jet in gamma-ray bursts (GRBs) or the central engine's memory effect. GRB 111012A adds to the rare population of candidate lensed GRBs, although no confirmed case of a gravitationally lensed GRB currently exists.

Keywords: Gamma-ray bursts
The Prevalence of Bursty Star Formation in Low-mass Galaxies at z = 1─7 from Hα-to-UV Diagnostics. We present an analysis of the bursty star formation histories (SFHs) of 346 star-forming galaxies at 1 ≲ z &lt; 7, selected from JWST/NIRSpec G395M and PRISM spectroscopy provided by the Cosmic Evolution Early Release Science (or CEERS) and Red Unknowns: Bright Infrared Extragalactic Survey (or RUBIES) surveys. We analyze the correlation of star formation rate versus stellar mass (the star-forming main sequence, SFMS) for our sample and find no significant difference between the intrinsic scatter in the Hα-based SFMS and the UV-continuum-based SFMS. However, the diagnostic power of the SFMS is limited at high redshift and low stellar mass due to observational biases that exclude faint, quenched galaxies. To more directly probe star formation variability, we examine the dust-corrected Hα-to-UV ratio, which is assumed to trace deviations from a constant SFH over the past ∼100 Myr. In our sample,  73−4+4 % of galaxies exhibit Hα-to-UV ratios inconsistent with a constant SFH. We do not observe any statistically significant evolution in the Hα-to-UV ratio with redshift. Additionally, lower-mass galaxies (7 ≤ log(M*/M⊙) &lt; 8.5) are 30% ± 1% more likely to lie above this equilibrium range—indicative of a recent (≲100 Myr) burst of star formation—compared to higher-mass systems (8.5 ≤ log(M*/M⊙) ≤ 10.9). These results suggest that bursty SFHs are more common in low-mass galaxies at z ∼ 1─7, and that this remains relatively stable across ∼0.8─6 Gyr after the Big Bang.

Keywords: Early universe, Galaxy formation, High-redshift galaxies, Galaxy evolution
Two Pathways of Turbulent Energy Processing in Solar Wind Current Sheets: Confined Fragmentation versus Organized Transport. Understanding how turbulent energy is dissipated in the heliosphere remains a central challenge in space plasma physics. While magnetic reconnection and other dissipative processes occurring within current sheets are widely regarded as leading channels for this dissipation, the fact that a solar wind reconnection exhaust is itself a current-sheet structure creates an inherent physical overlap, making it difficult to uniquely attribute observed energy conversion to either the global topology of the sheet or the active reconnection dynamics. In this paper, we provide observational evidence for two distinct pathways of turbulent energy processing in mesoscale solar wind current sheets. By preclassifying events according to the presence of reconnecting current sheets (RCSs) or the absence of nonreconnecting current sheets (NRCSs) of a reconnection jet and then applying a suite of scale-dependent and direction-resolved turbulence diagnostics, we identify two dynamical states. Lacking an efficient outflow, NRCSs tend to represent a state of "confined fragmentation," characterized by stronger small-scale fluctuations, more intense intermittency signatures, and a larger ion temperature enhancement, consistent with localized, fragmentation-driven dissipation. In contrast, RCSs embody a state of "organized transport," in which a coherent Alfvénic jet redistributes energy on large scales, yielding comparatively reduced small-scale intermittency, a more ordered internal magnetic structure, and a smaller ion temperature increase. This two-state paradigm offers a testable conceptual framework for how macroscopic transport channels modulate kinetic-scale turbulent dynamics, providing a new lens for interpreting energy dissipation in the solar wind and other collisionless plasmas.

Keywords: Interplanetary turbulence, Solar wind
Exploring the History of Stellar Mergers with Chemistry: Examining the Origins of Massive α-enriched Stars Using Carbon Isotope Ratios. Recently discovered massive α-enriched (MAE) stars have surface chemistry consistent with members of the older, thick-disk Milky Way population but high masses (∼1.5─3 M⊙) that suggest these stars are young. The origin of MAE stars is not fully understood, although binary interactions are likely an important formation pathway. To better constrain the history of MAE stars, we have measured metallicities, carbon isotope ratios, and CNO abundances in 49 red clump (RC) stars and four red giants. Our sample included thin-disk, thick-disk, and MAE stars to best constrain different formation scenarios. We observed our sample stars using the Tull Spectrograph on the McDonald 2.7 m telescope and derived abundances using synthetic spectra created by the Turbospectrum radiative transfer code. Overall, we find that 10 of our RC MAE stars are consistent with the average thick-disk carbon isotope ratio of 12C/13C = 8.2 ± 3.4. We find 5 MAE stars that have significantly higher carbon isotope ratios (12C/13C &gt; 15) than stars at similar metallicities. A total of 2 of the anomalous stars show abundance patterns consistent with asymptotic giant branch mass transfer, while 3 MAE stars have 12C/13C ratios similar to massive, single RC stars and show no clear signs of binarity from radial velocity monitoring or from the Gaia RUWE measurement. Overall, we find that carbon isotope ratio measurements provide a unique constraint when discerning the possible origins of MAE stars.

Keywords: Red giant clump, Stellar abundances, Galaxy stellar content
Fermi-GBM Observations of GRB 230307A: An Exceptionally Bright Long-duration Gamma-ray Burst with an Associated Kilonova. On 2023 March 7 the Fermi Gamma-ray Burst Monitor observed the second-highest-fluence gamma-ray burst (GRB) ever, GRB 230307A. With a duration beyond 100 s, GRB 230307A contained a multitude of rapidly varying peaks, and was so bright it caused instrumental effects in the GBM detectors. The high fluence of this burst, (6.02 ± 0.02) × 10−3 erg cm−2, prompted rapid follow-up across the electromagnetic spectrum including the discovery of an associated kilonova. GRB 230307A is one of a few long GRBs with an associated compact merger origin. Three main temporal regions of interest are identified for fine time-resolution spectral analysis: triggering pulse, main emission, and late emission, and the parameter evolution is traced across these regions. The high flux of the burst allowed for the statistical preference of a more complex, physically motivated model, the Double Smoothly Broken Power Law, over typical spectral fitting functions for GRBs. From this model the evolution of the parameters was found to be in accordance with those expected for synchrotron radiation in the fast-cooling regime. Additionally, it was found that the flux experiences a steep decline in late time intervals, a feature which is often attributed to high-latitude emission, which follows the dissipation episodes. Furthermore, GRB 230307A was found to have one of the highest inferred bulk Lorentz factors of Γ = 1600. GRB 230307A is a noteworthy burst in terms of flux alone, but additionally provides a unique insight into the possible temporal and spectral characteristics of a new long merger class of GRBs.

Keywords: Gamma-ray bursts
Probing the He II Reionization ERa via Absorbing C IV Historical Yield (HIERACHY). IV. A Complex Redshifted Absorption System Intrinsic to Quasar. High-resolution spectra provide a powerful tool in studying the associated absorption lines in quasars. We present a case study of the quasar J014741-030247 at z ∼ 4.75, which hosts complex intrinsic absorption lines revealed by the high-resolution Magellan/MIKE spectrum obtained from the HIERACHY program. We focus on one of the strongest absorption systems (z ∼ 4.7804) and determine the column densities of multiple ionization species. We find that the apparent optical depth method may significantly underestimate the column densities of high ions. Decomposing the absorption into multiple components yields a better fit and reveals clear evidence of partial coverage. The variation in covering fractions among different ions suggests that high ions are distributed more extensively in this system. We estimate electron densities of different components (630─4070 cm−3), these are based on the column densities of Si II* and C II*. By combining these with the hydrogen number density and ionization parameter derived from photoionization modeling, we infer that the different components are located at distances of 2.3─9.5 kpc from the quasar. The derived NH/ne and the partial coverage observed in low ions all require cloud sizes smaller than 1 pc, even down to 0.01 pc. Finally, the low kinetic luminosity of the gas (&lt;0.5%Lbol) indicates that it is insufficient to drive significant AGN feedback and may only suppress star formation via "multistage" mechanism.

Keywords: Metal line absorbers, Galaxy kinematics, Quasar absorption line spectroscopy