Sazuna/UAT_keywords huggingface dataset:
The AGORA High-resolution Galaxy Simulations Comparison Project. VIII. Disk Formation and Evolution of Simulated Milky Way Mass Galaxy Progenitors at 1 &lt; z &lt; 5. We investigate how differences in the stellar feedback produce disks with different morphologies in Milky Way─like progenitors over 1 ≤ z ≤ 5, using eight state-of-the-art cosmological hydrodynamics simulation codes in the AGORA project. In three of the participating codes, a distinct, rotation-dominated inner core emerges with a formation timescale of ≲300 Myr, largely driven by a major merger event, while two other codes exhibit similar signs of wet compaction—gaseous shrinkage into a compact starburst phase—at earlier epochs. The remaining three codes show only weak evidence of wet compaction. Consequently, we divide the simulated galaxies into two groups: those with strong compaction signatures and those with weaker ones. Galaxies in these two groups differ in size, stellar age gradients, and disk-to-total mass ratios. Specifically, codes with strong wet compaction build their outer disks in an inside-out fashion, leading to negative age gradients, whereas codes with weaker compaction feature flat or positive age gradients caused primarily by outward stellar migration. Although the stellar half-mass radii of these two groups diverge at z ∼ 3, the inclusion of dust extinction brings their sizes and shapes in mock observations closer to each other and to observed galaxies. We attribute the observed morphological differences primarily to variations in the stellar feedback implementations—such as delayed cooling timescales, and feedback strengths—that regulate both the onset and duration of compaction. Overall, our results suggest that disk assembly at high redshifts is highly sensitive to the details of the stellar feedback prescriptions in simulations.

Keywords: Galaxy disks, Galaxy dynamics, Galaxy kinematics
The Ultraviolet/Optical Continuum Reverberation Mapping of Eight Active Galactic Nuclei with Swift: Further Evidence for the Outer Component. In our previous work, we applied the ICCF-Cut method to the continuum reverberation mapping (CRM) of six active galactic nuclei (AGNs) based on the published Swift data. Extending this work, we perform a systematic AGN CRM study utilizing the Swift archive. We enlarge our sample with eight additional AGNs at z &lt; 0.05 with high-cadence (&lt;3 days) and multiband photometric observations. Time series analysis of these light curves shows two main results: (1) the interband lags are broadly consistent with τ ∝ λ4/3, while the average interband lags are larger than those predicted by the standard thin accretion disk model; (2) for most targets, there exists a U-band lag excess, which is probably due to the diffuse continuum emission from the broad-line region (BLR). We employ the ICCF-Cut method to extract the possible diffuse continuum component from the U-band light curves and calculate the diffuse continuum lags (τcut), which are generally consistent with the lags (τjav) derived by the JAVELIN photometric reverberation mapping model. Further analysis with our sample indicates a positive correlation between the diffuse continuum region size and the BLR size (RDCR─RBLR relation), as well as another correlation with the luminosity (RDCR─L relation). These findings provide further evidence for a significant contribution of diffuse continuum emission from the BLR to the AGN continuum lags.

Keywords: Accretion, Supermassive black holes, Reverberation mapping, Active galactic nuclei
Multiphase Gas Offsets in the Atmospheres of Central Galaxies and Their Consequences for SMBH Activation. I. The Hot and Warm Ionized Gas Phases. We investigate the spatial relationships between multiphase gas components and supermassive black hole (SMBH) activity in a sample of 25 cool-core galaxy groups and clusters. Using high-angular-resolution observations from Chandra, the Very Large Telescope/Multi Unit Spectroscopic Explorer, and the Very Long Baseline Array (VLBA), we robustly locate the positions, respectively, of the X-ray peak of the intracluster medium, of the Hα peak of the warm ionized gas, and of the SMBH radio core, on parsec scales. We identify spatial offsets between the X-ray peak of the hot gas and the SMBH in 80% of the systems, with an average displacement of  &lt;∆X-raySMBH&gt;=4.8  kpc (dispersion of 3.8 kpc). In contrast, the peak of warm ionized gas traced by Hα exhibits a much smaller offset ( &lt;∆HαSMBH&gt;=0.6  kpc; dispersion of 1.4 kpc) and a lower incidence of displacement (15%). Our findings suggest that hot-gas sloshing primarily drives the observed spatial offsets, with active galactic nucleus (AGN)─driven uplift contributing in some systems. Importantly, systems with Hα─SMBH offsets of ≥1 kpc uniformly lack detectable radio cores on VLBA scales, with upper limits on the 5 GHz power of P5GHz ≤ 1021─22 W Hz−1, while those without such offsets exhibit radio-powerful AGNs with parsec-scale radio emission up to P5GHz ∼ 1024─25 W Hz−1. This correlation indicates that centrally concentrated warm gas is critical for sustaining radio-loud SMBH activity, possibly supporting scenarios of cold-mode accretion. Overall, our results highlight the importance of high-angular-resolution multiwavelength observations for understanding the interplay between multiphase gas cooling and AGN fueling in central galaxies.

Keywords: Accretion, Supermassive black holes, Galaxy clusters, X-ray astronomy, Cooling flows, Galaxy groups, Galaxy evolution, Interstellar medium, Intracluster medium
A Comprehensive Gaia Spectroscopic Study of Stars in the Scorpius-Centaurus Complex: Star Formation History and Disk Lifetime. We re-evaluate the star formation history of the nearby Scorpius-Centaurus (Sco-Cen) OB Association with a comprehensive analysis of Gaia XP spectra of more than 7800 potential members. New spectral classifications are obtained by fitting individual XP spectra with templates derived from empirical spectra of young stars. Combining these spectral classifications in this work and in the literature with archival photometry leads to estimates of V-band extinction and stellar luminosities for a total of 8846 sources. Employing SPOTS models with spot coverages of 0.34 and 0.51 for K- and M-type stars harmonizes age estimates between K/M-type and F/G-type stars, with ages older than are obtained for low-mass stars from standard evolutionary models. These older ages lead to a disk lifetime that is approximately two times longer than reported in previous literature. Our re-evaluation of the star formation history with these revised age estimates uncovers evidence of underlying substructures within the Sco-Cen complex.

Keywords: Stellar associations, Star formation, Low mass stars, OB associations
JWST Observations of SN 2024ggi. I. Interpretation and Model Comparison of the Type II Supernova 2024ggi at 55 Days past Explosion. We present panchromatic 0.4─21 μm observations of the nearby (∼7.2 Mpc) Type II supernova (SN) 2024ggi, obtained during the plateau phase at ∼55 days past explosion. Our data set includes JWST spectra spanning 1.7─14 μm, mid-infrared (MIR) imaging at 7.7 and 21 μm, and near-simultaneous ground-based optical and near-infrared (NIR) spectra covering 0.32−1.8 μm. The NIR and MIR spectral features of SN 2024ggi are dominated by H I emission. We present line IDs and a toy PHOENIX/1D model that reproduces the observations well, especially the continuum redward of 0.9 μm. We compare SN 2024ggi to SN 2022acko and SN 2023ixf, two other Type II SNe that were also observed by JWST, and highlight key similarities and differences in their spectral features. No evidence for a MIR excess or dust is found at these epochs, with the model matching the observed flux out to 21 μm. We discuss the model's shortcomings, focusing on the density profile, which suppresses line blanketing and produces features in the optical that are too narrow. Our results show the power of panchromatic studies in both exploring the nature of the SN ejecta and constraining detailed models of SNe.

Keywords: Type II supernovae, Spectroscopy
Impact of the Latest <SUP>22</SUP>Ne+α Reaction Rates on Nucleosynthesis in Massive Stars and Galactic Chemical Evolution. In massive stars (initial mass of ≳9 M⊙), the weak s- (slow neutron capture) process produces elements between Fe and Zr, enriching the Galaxy with these elements through core-collapse supernova explosions. The weak s-process nucleosynthesis is driven by neutrons produced in the 22Ne(α, n)25Mg reaction during convective He core and C shell burning. The yields of heavy elements thus depend on the 22Ne(α, n)25Mg and the competitive 22Ne(α, γ)26Mg reaction rates, which are dominated by several narrow-resonance reactions. While the accuracy of these rates has been under debate for decades, recent experimental efforts, including ours, drastically reduced these uncertainties. In this work, we use a set of 280 massive star nucleosynthesis models calculated using different 22Ne(α, n)25Mg and 22Ne(α, γ)26Mg rates and a galactic chemical evolution (GCE) study to probe their impact on the weak s-process elemental abundances in the Galaxy. The GCE was computed with the OMEGA+ code, using the new sets of stellar yields with different 22Ne+α rates. From GCE, we find that these rates are causing up to 0.45 dex of variations in the [Cu/Fe], [Ga/Fe], and [Ge/Fe] ratios predicted at solar metallicity. The greatest impact on the stellar nucleosynthesis and GCE results derives from uncertainties in the (α, n) strength (ωγ(α,n)) of the Ex = 11.32 MeV resonance. We show that variations observed in the GCE calculations for weak s-process elements become negligibly smaller than dispersions found in observations once the ωγ(α,n) is accurately determined within the uncertainty of 10%─20% (typically reported experimental errors for the resonance) in future nuclear physics experiments.

Keywords: Stellar nucleosynthesis, S-process, Core-collapse supernovae, Galaxy chemical evolution
Ultrahigh-energy Cosmic Rays from Neutrino-emitting Tidal Disruption Events. We revisit ultrahigh-energy cosmic-ray (UHECR) production in tidal disruption events (TDEs) in light of recent evidence of neutrino-TDE associations. We use an isotropically emitting source-propagation model, which has been developed to describe the neutrino production in AT2019dsg, AT2019fdr, and AT2019aalc. These TDEs have strong dust echoes in the infrared (IR) range, which are potentially linked to the neutrino production. A mechanism where neutrinos originate from cosmic-ray (CR) scattering on IR photons implies CRs in the ultrahigh-energy range, thus suggesting a natural connection with the observed UHECR. We extrapolate the three TDE associations to a population of neutrino- and UHECR-emitting TDEs, and postulate that these TDEs power the UHECRs. We then infer the source composition, population parameters, and local rates that are needed to describe UHECR data. We find that UHECR data point toward a mix of light to mid-heavy injection isotopes, which could be found, e.g., in oxygen-neon-magnesium white dwarfs, and to a contribution of at least two groups of TDEs with different characteristics, dominated by AT2019aalc-type events. The required local TDE rates of  O(102)Gpc−3yr−1 , however, are more indicative of the disruption of main-sequence stars. We propose an enhanced efficiency in the acceleration of heavier nuclei that could address this discrepancy. The predicted diffuse neutrino fluxes suggest a population of astrophysical neutrino sources that can be observed by future radio neutrino detection experiments. The derived source parameters are consistent with those expected from the individual neutrino observations.

Keywords: High energy astrophysics, Neutrino astronomy, Tidal disruption, Ultra-high-energy cosmic radiation
Helium-3 Enrichment in Gradual Solar Energetic Particle Events: Evidence for a Jet-supplied Seed Population. Enhancements in 3He abundance, a characteristic feature of impulsive solar energetic particle (ISEP) events, are also frequently observed in gradual solar energetic particle (GSEP) events. Understanding the origin of this enrichment is crucial for identifying the mechanisms behind solar energetic particle (SEP) generation. We investigate the origin of 3He enrichment in high-energy (25─50 MeV) solar proton events observed by the Solar and Heliospheric Observatory, selecting events that coincide with ≲1 MeV nucleon−1 3He-rich periods detected by the Advanced Composition Explorer during 1997─2021. The identified 3He enhancements include cases where material from independent impulsive (3He-rich) SEP events is mixed with GSEP proton populations. Two high-energy proton events exhibit elemental composition and solar source characteristics consistent with ISEPs. Extreme-ultraviolet imaging from the Solar Dynamics Observatory and STEREO reveals narrow, jetlike eruptions in the parent active regions of about 60% of the remaining events. Notably, the highest 3He/4He ratios occur when coronal jets are present, consistent with fresh, jet-driven injection of suprathermal 3He that is subsequently reaccelerated during the event. Correspondingly, jet-associated events show fewer preevent (residual) 3He counts, indicating that enrichment in these cases does not primarily come from remnant material. We find a positive correlation between 3He/4He and Fe/O, strongest in jet-associated events, consistent with a common jet-supplied seed population reaccelerated by the coronal mass ejection shock.

Keywords: Solar energetic particles, Solar abundances, Solar active regions, Solar extreme ultraviolet emission
The Optical Photometric Variability of Herbig Ae/Be Stars from TESS. We have carried out a photometric time domain study of 188 intermediate-mass young stars observed in Full Frame Image mode with the Transiting Exoplanet Survey Satellite (TESS) satellite over the first 3.3 yr of its mission. The majority of these targets are classified as Herbig Ae/Be stars (HAeBes). All were monitored at optical wavelengths for at least one 27 day TESS sector, with many having multiple sectors of data. From a custom aperture photometry pipeline, we produced light curves and analyzed the variability therein, as a function of stellar and circumstellar properties. Based on visual and statistical analysis, we find that ∼95% of HAeBes are variable on timescales of 10 minutes to one month, with the most common light-curve morphology being stochastic. Approximately 15% of the set display quasiperiodic variability. In comparison to sets of low-mass T Tauri stars monitored with optical space telescopes, the Herbig Ae/Be stars display a much lower incidence of "dipper" behaviors (quasiperiodic or aperiodic fading events), as well as periodic modulations. As posited by previous work, we conclude that magnetic starspots are rare on HAeBes, and that the inner circumstellar dust rims of these objects lie at substantially larger radii than for low-mass young stars. Beyond these differences, the accretion dynamics of young stars less than ∼7M⊙ appear to be largely consistent based on their time domain properties from data streams of up to three months' duration. We do, however, find tentative evidence for a change in variability amplitude above this mass boundary, particularly for quasiperiodic behavior.

Keywords: Herbig Ae/Be stars, Light curve classification , Young stellar objects, Pre-main sequence stars, Stellar accretion, Circumstellar disks, Time series analysis
Enigmatic Centi-SFU and mSFU Nonthermal Radio Transients Detected in the Middle Corona. Decades of solar coronal observations have provided substantial evidence for accelerated particles in the corona. In most cases, the location of particle acceleration can be roughly identified by combining high spatial and temporal resolution data from multiple instruments across a broad frequency range. In almost all cases, these nonthermal particles are associated with quiescent active regions, flares, and coronal mass ejections (CMEs). Only recently, some evidence of the existence of nonthermal electrons at locations outside these well-accepted regions has been found. Here, we report for the first time multiple cases of transient nonthermal emissions, in the heliocentric range of ∼3─7R⊙, which do not have any obvious counterparts in other wave bands, like white-light and extreme ultraviolet. These detections were made possible by the regular availability of high dynamic-range low-frequency radio images from the Owens Valley Radio Observatory's Long Wavelength Array. While earlier detections of nonthermal emissions at these high heliocentric distances often had comparable extensions in the plane of sky, they were primarily associated with radio CMEs, unlike the cases reported here. Thus, these results add on to the evidence that the middle corona is extremely dynamic and contains a population of nonthermal electrons, which is only becoming visible with high dynamic-range low-frequency radio images.

Keywords: Solar coronal transients, Solar radio emission, Solar corona
The ZZ Ceti Instability Strip for the Most Massive White Dwarf Pulsators. We present time-series photometry of 31 massive DA white dwarfs with M ≳ 0.9 M⊙ within the ZZ Ceti instability strip from the Montreal White Dwarf Database 100 pc sample. The majority of the targets had no previous time-series photometry available, though several were classified as nonvariable or potential pulsators in the literature. Out of the 31 candidates, we confirm 16 as pulsating. Our observations at three observatories have led us to discover the most massive pulsating white dwarf currently known, J0959−1828 (M = 1.32 or 1.27 M⊙ for a CO versus ONe core), which is slightly more massive than the previous record holder J0049−2525. We study the sample properties of massive ZZ Ceti white dwarfs and find several trends with their weighted mean periods. As predicted by theory, we see an increase in the weighted mean periods with decreasing effective temperature and a decrease in pulsation amplitudes at the red edge of the instability strip. Furthermore, the weighted mean periods decrease with increasing stellar mass. Our observations show that the ZZ Ceti instability strip may not be pure at high masses. This is likely because the nonvariable white dwarfs in the middle of the strip may be weakly magnetic, which could escape detection in the available low-resolution spectroscopy data, but may be sufficient to suppress pulsations. Extensive follow-up observations of the most massive white dwarfs in our sample have the potential to probe the interior structures and core compositions of these white dwarfs with significantly crystallized cores.

Keywords: White dwarf stars, ZZ Ceti stars, Stellar pulsations
A Face-on Accretion Disk Geometry Revealed by Millimeter-wave Periodicity in Sgr A<SUP>∗</SUP>. We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array archival data to investigate flux variability in Sagittarius A∗, the supermassive black hole at the Galactic center. Among these, we identified a rare but unusually clear and coherent ∼52 minute sinusoidal modulation at 230 GHz, with a statistical significance exceeding 5σ. Modeling with a Doppler-boosted hotspot scenario yields an orbital radius of ∼4 Schwarzschild radii and a disk inclination of 8°(or 172°), providing the first direct millimeter wavelength constraint on the inner accretion flow geometry. This nearly face-on inclination is in good agreement with previous constraints from GRAVITY and Event Horizon Telescope observations. These findings provide robust, independent evidence that millimeter-wave periodicity can directly probe the innermost accretion flow geometry, offering a powerful complement to variability studies at infrared and X-ray wavelengths.

Keywords: Millimeter astronomy, Black hole physics, Galaxy accretion disks, Galaxy accretion
Lu and Hamilton Model for Solar Flares over a Rewiring Complex Network. We present a modified Lu &amp; Hamilton─type model where the neighborhood relations are replaced by topological connections, which can be dynamically altered. The model represents each grid node as a flux tube, as in the classic model, but with connections evolving to capture the complex effects of magnetic reconnection. Through this framework, we analyze how the dissipated energy distribution changes, particularly focusing on the power-law exponent αE, which decreases with respect to the original model due to rewiring effects. When the system is dominated by rewiring, it presents an exponential distribution exponent βE, showing a faster decay of dissipated energy than in the original model. This leads to microflare-dominated dynamics at short timescales, causing the system to lose the scale-free behavior observed in both the original model and in configurations where energy release is primarily driven by forcing rather than rewiring. Our results reveal a clear transition from power-law to exponential regimes as the rewiring probability increases, fundamentally altering the energy distribution characteristics of the system. In contrast, when considering topological neighbors instead of local ones, the model's dynamics become intrinsically nonlocal. This leads to scaling exponents comparable to those reported in other nonlocal dynamical systems.

Keywords: Solar magnetic fields, Solar flares, Solar corona
Emission and Absorption Features of Magnetically Driven Disk Winds in Black Hole X-Ray Binaries. We investigate accretion disk winds commonly observed in Galactic black hole (BH) X-ray binaries (XRBs), which manifest as blueshifted absorption features in X-ray spectra. We model these winds as ideal magnetohydrodynamic outflows of hot plasma driven by global magnetic fields threading the accretion disk around the BH. Using Monte Carlo simulations with Monte Carlo Simulations for Astrophysics and Cosmology, we solve three-dimensional radiative transfer equations to determine the large-scale ionization structure that produces the observed ionic column densities. Focusing on the high/soft state of the BH XRB, where disk emission provides the dominant source of ionizing X-rays, we calculated synthetic spectra showing resonance absorption and scattered emission from ions in various charge states. Our results demonstrate that systems viewed at high polar angles exhibit prominent multi-ion absorption lines with asymmetric profiles, accompanied by P-Cygni-like emission features that partially reproduce the characteristics seen in the observed spectra. This further implies that even a dense disk wind with a high polar angle is unlikely to be saturated due to effective scattering.

Keywords: X-ray astronomy, Radiative transfer, High energy astrophysics, Astrophysical black holes
Studying the Power Sources behind Type Ic Supernovae. Astrophysical transients can be powered by a broad range of energy sources, including shock heating (internal and external shocks), decay of radioactive isotopes, and long-lived central engines (magnetar and fallback). The dominant energy source for astrophysical transients depends on the nature of the explosive engine and its progenitor. To model all transients, light-curve codes must include all of these energy sources. Here, we present a supernova light-curve code implementing analytic source models to compare the role of different energy sources in these transients. To demonstrate the utility of this code, we conduct an extensive study of Type Ic broad-line (Ic-BL) supernovae. A diverse set of energy sources have been linked to Ic-BL supernovae, making them an excellent candidate for this light-curve code. In this paper, we explore which features of the explosion (mass, velocity, etc.) affect the Type Ic supernovae light curves, focusing on shock-interaction and radioactive-decay energy sources. Although the explosion properties under both energy sources can be tuned to match the peak emission, matching the light-curve evolution in many Ic-BL supernovae requires fine-tuned conditions. We find that shock interactions in the stellar wind are likely to be the dominant energy source at peak for these supernovae.

Keywords: Type Ic supernovae, Transient sources, Supernovae