Sazuna/UAT_keywords huggingface dataset:
An Integral-based Technique to Accelerate the Monte Carlo Radiative Transfer Computation for Supernovae. We present an integral-based technique (IBT) algorithm to accelerate supernova (SN) radiative transfer calculations. The algorithm utilizes "integral packets," which are calculated by the path integral of the Monte Carlo (MC) energy packets, to synthesize the observed spectropolarimetric signal at a given viewing direction in a 3D time-dependent radiative transfer program. Compared to the event-based technique (EBT) proposed by M. Bulla et al., our algorithm significantly reduces the computation time and increases the MC signal-to-noise ratio (S/N). Using a 1D spherical symmetric Type Ia SN ejecta model DDC10 and its derived 3D model, the IBT algorithm has successfully passed the verification of spherical symmetry and cross comparison on a 3D SN model with the direct-counting technique and EBT. Notably, with our algorithm implemented in the 3D MC radiative transfer code SEDONA, the computation time is faster than EBT by a factor of 10‑30, and the S/N is better by a factor of 1.5‑3, with the same number of MC quanta.

Keywords: Radiative transfer simulations, Spectropolarimetry, Supernovae
The Blooming Tree Algorithm at Work: Clusters, Filaments, and Superclusters in the Field of A2029. The Blooming Tree (BT) algorithm, based on the hierarchical clustering method, is designed to identify clusters, groups, and substructures from galaxy redshift surveys. We apply the BT algorithm to a wide-field (10 × 10 deg2) spectroscopic data set centered on the galaxy cluster A2029. The BT algorithm effectively identifies all the X-ray luminous clusters and most of the optical clusters known in the literature, numerous groups, and the filaments surrounding the clusters, associating a list of galaxy members to each structure. By lowering the detection threshold, the BT algorithm also identifies the three superclusters in the field. The BT algorithm arranges the clusters and groups that make up the superclusters in a hierarchical tree according to their pairwise binding energy: the algorithm thus unveils the possible accretion history of each supercluster and their future evolution. These results show how the BT algorithm can represent a crucial tool to investigate the formation and evolution of cosmic structures on nonlinear and mildly nonlinear scales.

Keywords: Galaxy clusters, Superclusters, Galaxy groups, Abell clusters, Single-linkage hierarchical clustering
Impacts of the Metagalactic Ultraviolet Background on Circumgalactic Medium Absorption Systems. Among the many different pieces of physics that go into simulations of the circumgalactic medium (CGM), the metagalactic ultraviolet background (UVB) plays a significant role in determining the ionization state of different metal species. However, the UVB is uncertain, with multiple models having been developed by various research groups over the past several decades. In this work, we examine how different UVB models influence the ionic column densities of CGM absorbers. We use these UVB models to infer ion number densities in the Figuring Out Gas and Galaxies In Enzo (FOGGIE) galaxy simulations at z = 2.5 and use the Synthetic Absorption Line Surveyor Application package to identify absorbers. Absorbers are then matched across UVB models based on their line-of-sight position so that their column densities can be compared. From our analysis, we find that changing the UVB model produces significant changes in ionization, specifically at lower gas densities and higher temperatures where photoionization dominates over collisional ionization. We also find that the scatter of column density differences between models tends to increase with increasing ionization energy, with the exception of H I, which has the highest scatter of all species we examined.

Keywords: Hydrodynamical simulations, Circumgalactic medium
Morphological Demographics of Galaxies at z ∼ 10–16: Log-normal Size Distribution and Exponential Profiles Consistent with the Disk Formation Scenario. We homogeneously investigate the morphological properties of 169 galaxies at z ∼ 10–16 with deep JWST NIRCam images employing our established techniques of GALFIT modeling and uncertainty evaluation (systematics+statistics). We obtain effective radii re ranging 20–500 pc, with a distribution significantly broader than the scatter made by the uncertainties. We find that the re distribution is well described by a log-normal distribution with a mean of  re=133‑12+13  pc and a standard deviation of  σlnre=0.52±0.08 . The standard deviation is comparable to that of local galaxies, indicating no significant evolution over z ∼ 0–10. We also find that the axis ratio distribution is nearly uniform, statistically similar to that of local spirals. We estimate the virial radius rvir from the stellar masses via the star formation main sequence and stellar-to-halo mass relation, obtaining a stellar-to-halo size ratio  re/rvir=0.015‑0.005+0.015 , which is comparable to those of star-forming galaxies in the local and low-z Universe. Our results of (1) the log-normal re distribution, (2) the uniform axis ratio distribution, and (3) a mean radial profile consistent with an exponential profile (n = 1.3 ± 0.6) suggest that galaxies at z ∼ 10–16 generally follow the classical galaxy disk formation scenario with a specific disk angular momentum fraction of jd/md ∼ 0.5–1. Interestingly, we identify two remarkable outliers GN-z11 (zspec = 10.60) and GHZ2 (zspec = 12.34) with  re=55‑6+5  pc and 39 ± 11 pc, respectively, that may not be explained by disk structures but by active galactic nucleus or compact star-forming galaxies merging underway in short periods of time, as reproduced in numerical simulations.

Keywords: Galaxy formation, Galaxy structure, Galactic and extragalactic astronomy, Galaxy evolution, Lyman-break galaxies, High-redshift galaxies, Galaxies, Galaxy radii
Constrain the Hubble Constant from Extreme Mass Ratio Inspirals Dark Sirens Using Galaxy Clusters. Extreme mass ratio inspirals (EMRIs) are key observational targets for future space-based gravitational wave detectors and hold significant value in cosmological research. As a type of "standard siren," EMRIs offer an independent method to measure the Hubble constant, providing new hope for resolving the "Hubble tension" problem. However, when using the dark siren method combined with galaxy catalogs to statistically infer redshifts, EMRI events occurring in low-luminosity galaxies may not be fully recorded in the galaxy catalogs, leading to potential true hosts being missed. To address this, we propose using galaxy cluster catalogs, which contain numerous member galaxies, including faint ones, effectively reducing the risk of missing true hosts. In this study, we randomly injected three EMRI events and simulated a 2 yr observation of these events using both Laser Interferometric Space Antenna (LISA) and the joint LISA–Taiji network to demonstrate the improvements brought about by incorporating galaxy cluster catalogs into the dark siren methodology. For these three cases, compared to using galaxy catalogs alone, incorporating galaxy cluster catalogs enhanced the measurement precision of the Hubble constant to varying degrees, with a maximum improvement of approximately 41.00%. These results indicate that employing galaxy cluster catalogs in EMRI-based dark siren analyses can more effectively constrain the Hubble constant H0.

Keywords: Hubble constant, Gravitational waves, Black holes
XRISM Reveals Complex Ionization and Velocity Structures in the GX 340+0 X-Ray Binary. We present the first high-resolution XRISM spectrum of the neutron star low-mass X-ray binary GX 340+0, revealing unprecedented detail in its emission and absorption features. The spectrum reveals a rich and complex Fe XXV Heα line profile and a P Cygni profile from Ca XX. We use the state-of-the-art spectral synthesis code CLOUDY to model the emission and absorption features in detail. Our analysis reveals multi-ionization and multivelocity structures, where the combination of broad (∼800 km s−1) and narrow (∼360 km s−1) line components, along with rest-frame and blueshifted emission and absorption lines, accounts for the observed line profile complexity. We identify a modest ∼2735 km s−1 accretion disk wind exhibiting both absorption and emission features. We also detect a relativistic reflection feature in the spectrum, which we model using relxillNS, specifically designed to characterize X-ray reprocessing in accretion disks around neutron stars. Furthermore, we examine the detailed physics of the Fe XXV Heα complex, focusing on the forbidden-to-resonance line ratio under the influence of continuum pumping and optical depth effects.

Keywords: High resolution spectroscopy, Low-mass x-ray binary stars
γ-Ray Pulsar Emission is Mostly Stable on Timescales from Minutes to Years. We present a method for the detection and characterization of random changes in the flux from γ-ray pulsars on sub-hour timescales, much shorter than variations that can be accessed using direct flux measurements. Flux variations are a proxy for the variations in spindown power ( Ė ) or particle acceleration, which can be produced by random switches between quasi-stable configurations of the pulsar magnetosphere. This technique therefore probes the stability of pulsar magnetospheres and discrete spindown states on timescales much shorter than can be achieved with pulsar timing. We apply the method to a sample of 115 bright γ-ray pulsars, finding no new instances of state changes. We derive the sensitivity of the method and find that, for a wide range of possible state-changing models, over a wide range of timescales, we can limit the amplitude of flux ( Ė ) variations to &lt;10%. Substantial nulling is excluded in nearly all cases. The best cases limit variations of any sort to ≤1%. These results indicate that γ-ray pulsar magnetospheres maintain a single configuration or narrow range of configurations with nearly constant power output.

Keywords: Gamma-ray astronomy, Rotation powered pulsars, Pulsars
White Dwarfs in Wide Binaries: The Strong Effects of Stellar Evolution and Mass Loss. We examine the statistics of main-sequence/main-sequence, main-sequence/white-dwarf, and white-dwarf/white-dwarf wide binaries at 102.5–104 au separations in Gaia data. For binaries containing a white dwarf, we find a complex dependence of the wide-binary fraction on the white-dwarf mass, including a steep decline as a function of mass at &gt;0.6 M⊙. Furthermore, we find that wide binaries containing white dwarfs have significantly lower eccentricities than main-sequence binaries at the same separations. To model these observations, we compute the effects of post-main-sequence mass loss on the orbital parameters of wide binaries in all regimes of timescales, from secular to impulsive, and incorporate these dynamics in a population synthesis model. We find that adiabatic expansion of the orbits in binaries with slow enough evolutionary processes is the most likely explanation for the puzzling eccentricity distribution of white-dwarf wide binaries. The steeply declining white-dwarf binary fraction as a function of mass requires that the timescale for mass loss must be significantly shorter for high-mass stars (103–104 yr) than for the low-mass ones. We confirm previous studies that suggested that recoil in the range 0.25–4 km s‑1 is required to explain the observed distribution of separations of white-dwarf wide binaries. Finally, for low-mass white dwarfs (&lt;0.5 M⊙), we see interesting signatures of their formation due to close binary evolution in their wide-binary statistics. Our observations and modeling provide a novel dynamical constraint on the mass-loss stages of stellar evolution that are difficult to probe with direct observations.

Keywords: Binary stars, Late stellar evolution, White dwarf stars, Stellar mass loss, Wide binary stars
JWST Q3D Program: Active Galactic Nucleus Photoionization and Shock Ionization in a Red Quasar at z = 0.4. Red quasars, often associated with potent [O III] outflows on both galactic and circumgalactic scales, may play a pivotal role in galactic evolution and black hole feedback. In this work, we explore the [Fe II] emission in one such quasar at z = 0.4352─F2M J110648.32+480712.3 using the integral field unit mode of the Near Infrared Spectrograph aboard the JWST. Our observations reveal clumpy [Fe II] gas located to the south of the quasar. By comparing the kinematics of [Fe II] and [O III], we find that the clumpy [Fe II] gas in the southeast and southwest aligns with the outflow, exhibiting similar median velocities up to v50 = 1200 km s−1 and high velocity widths W80 &gt; 1000 km s−1. In contrast, the [Fe II] gas to the south shows kinematics inconsistent with the outflow, with W80 ∼ 500 km s−1, significantly smaller than the [O III] at the same location, suggesting that the [Fe II] may be confined within the host galaxy. Utilizing standard emission-line diagnostic ratios, we map the ionization sources of the gas. According to the MAPPINGS III shock models for [Fe II]/Paβ, the regions to the southwest and southeast of the quasar are primarily photoionized. Conversely, the [Fe II] emission to the south is likely excited by shocks generated by the back-pressure of the outflow on the galaxy disk, a direct signature of the impact of the quasar on its host.

Keywords: AGN host galaxies, Shocks, Radio quiet quasars
The Diversity of Metal Enrichment and Abundance Patterns at High Redshift: A Magellan Survey of Gas-rich Galaxies Traced by Damped Lyα Absorbers at z ∼ 5. A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Lyα absorbers (DLAs) in the early Universe. We conducted a survey aimed at discovering DLAs along sight lines to high-z quasars in order to measure element abundances at z &gt; 4. Here we report our first results from this survey for 10 DLAs with redshifts of ≈4.2–5.0. We determine abundances of C, O, Si, S, and Fe, and thereby the metallicities and dust depletions. We find that DLA metallicities at z &gt; 4.5 show a wide diversity spanning ∼3 orders of magnitude. The metallicities of DLAs at 3.7 &lt; z &lt; 5.3 show a larger dispersion compared to that at lower redshifts. Combining our sample with the literature, we find a relatively smooth evolution of metallicity with redshift out to z ∼ 5.3, with a tentative (∼2σ) indication of a slight rise in metallicity at 4.5 &lt; z &lt; 5.3. The relative abundances exhibit C enhancement for both metal-poor and metal-enriched DLAs. In addition, α-element enhancement is evident in some DLAs, including a DLA at z = 4.7 with a supersolar metallicity. Comparing [C/O] and [Si/O] with model predictions, four DLAs in our survey seem consistent with a nonzero Population III contribution (three with ≳30% Population III contribution). Combining our sample and the literature, we find the dust depletion strength and dust-to-metal ratios to correlate positively with the total (gas+solid phase) metallicity, confirming the presence of metal-rich, dusty DLAs even at ∼1 billion years after the Big Bang.

Keywords: Interstellar dust, Galaxy chemical evolution, Quasar absorption line spectroscopy, Abundance ratios, Galaxy abundances, Circumgalactic medium, Galaxies
The 2021 Hot-type Symbiotic Outburst of YY Herculis: An Optical Follow-up Study. We have followed up on the hot-type classical symbiotic outburst reported in YY Her using the Himalayan Chandra Telescope. The outburst coincides with the secondary minima of the system. Approximately 12 similar brightening events have been reported between 1890 and 2020, with only the 1993 outburst being studied spectroscopically. In our study, we monitored the system from 2021 to 2023, covering ∼1.5 orbital cycles, providing an opportunity to understand the spectral evolution of the outburst over a complete orbital period of YY Her. We found that the temperature and luminosity estimations based on emission line fluxes exhibit orbital phase dependence. The values estimated at phase 0.5, corresponding to the secondary minimum, were the most reliable. The temperature of the hot component is ≍1.41 × 105 K, and the luminosity is ≍1020 L⊙ during the outburst, reduced to ≍1.3 × 105 K and ≍830 L⊙ after one orbital cycle at phase 0.5. Temperature estimations during the outbursts suggest that YY Her exhibits both hot-type (2021) and cool-type (1993) behavior, similar to another symbiotic star, AG Dra. Using variations of the Ca II absorption lines, we confirmed the contribution of the ellipsoidal effect in secondary minima in the YY Her light curve.

Keywords: Spectroscopic binary stars, Z Andromedae stars, Spectroscopy, Symbiotic binary stars, Spectrophotometry
Gamma-Ray Burst Pulse Structures and Emission Mechanisms. The prompt phase X-ray and gamma-ray light curves of gamma-ray bursts (GRBs) exhibit erratic and complex behaviors, often with multiple pulses. The temporal shape of the individual pulses is often modeled as "fast rise exponential decay" (FRED). Here, we introduce a novel fitting function to quantify the pulse asymmetry. We conduct a light-curve and a time-resolved spectral analysis on 61 pulses from 22 GRBs detected by the Fermi Gamma-ray Burst Monitor. Contrary to previous claims, we find that only ∼50% of the pulse light curves in our sample show a FRED shape, while about 25% have a symmetric light curve, with the other 25% having a mixed shape. Furthermore, our analysis reveals a clear trend: in multipulse bursts, the initial pulse tends to exhibit the most symmetric light curve, while subsequent pulses become increasingly asymmetric, adopting a more FRED-like shape. Additionally, we correlate the temporal and spectral shapes of the pulses. By fitting the spectra with the classical "Band" function, we find a moderate positive Spearman's correlation index of 0.23 between the pulse asymmetry and the low-energy spectral index  αmax  (the maximum value across all time bins covering an individual pulse). Thus, during GRB light curves, the pulses tend to get more asymmetric and spectrally softer with time. We interpret this as a transition in the dominant emission mechanism, from photospheric (symmetric-like and hard) to nonthermal emission above the photosphere, and show that this interpretation aligns with a GRB jet Lorentz factor of the order of a few tens in many cases.

Keywords: Light curves, Gamma-ray bursts, Relativistic jets, Astronomy data analysis
Follow-up Investigation of 11 Pulsars Discovered in the Commensal Radio Astronomy FAST Survey. In this paper, we study 11 pulsars that were discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey. We report their phase-connected timing ephemeris, polarization pulse profiles, and Faraday rotation measures. The timing analysis shows that our sample includes seven normal pulsars and four (PSRs J0245+3219, J1437+3049, J1759−1248, and J1813−0852) millisecond pulsars, with periods ranging from 3.15 ms to 2.54 s, characteristic ages from 5.48 × 105 to 1.06 × 1010 yr, and surface magnetic fields from 1.46 × 108 to 1.18 × 1013 G. Six normal pulsars exhibit rich radiation characteristics, including nulling and subpulse drifting. PSR J0245+3219 (30.93 ms) has a spin period, characteristic age, surface magnetic field, and galactic height that are consistent with the parameters of disrupted recycled pulsars. PSR J1813−0852 (4.23 ms) is in a binary system with an orbit of 83.47 days, an eccentricity of 2.9 × 10−4, and its companion has a mass ranging from 0.28 to 0.76 M⊙. PSR J1813−0852 exhibits a spin period, companion mass, and orbital eccentricity that align well with the predicted characteristics of a millisecond pulsar─helium white dwarf systems.

Keywords: Millisecond pulsars, Binary pulsars, Pulsars
Dynamo Confinement of a Radiatively Spreading Solar Tachocline Revealed by Self-consistent Global Simulations. The helioseismically observed solar tachocline is a thin internal boundary layer of shear that separates the rigidly rotating solar radiative zone from the differentially rotating convective zone and is believed to play a central role in the 22-yr solar dynamo cycle. The observed thinness of the tachocline has long been a mystery, given the expected tendency of such shear to undergo radiative spreading. Radiative spreading is the process by which the meridional circulation and angular velocity burrow into a stably stratified fluid owing to the mitigating effect of radiative thermal diffusion. A confinement mechanism is thus required to keep the tachocline so thin. In previous work using global dynamo simulations, we achieved a statistically stationary confined tachocline for which the confinement mechanism was derived from the Maxwell stresses arising from a dynamo-generated nonaxisymmetric poloidal magnetic field. However, the parameters chosen meant that the tachocline was confined against viscous spreading instead of radiative spreading. Here, we show that this previously identified dynamo confinement scenario still succeeds in a simulation that lies in the more solar-like radiative spreading regime. In particular, a nonaxisymmetric, quasi-cyclic dynamo develops in the convective zone and overshoot layer, penetrates into the radiative zone via a novel type of skin effect, and creates Maxwell stresses that confine the tachocline over many magnetic cycles. To the best of our knowledge, this is the first fully self-consistent rendering of a confined tachocline in a global numerical simulation in the parameter regime appropriate to the Sun.

Keywords: Solar radiative zone, Solar differential rotation, Solar interior, Solar convective zone, Solar dynamo
Precovery Observations of 3I/ATLAS from TESS Suggest Possible Distant Activity. 3I/ATLAS is the third macroscopic interstellar object detected traversing the solar system. Since its initial discovery on UT 2025 July 1, hundreds of hours on a range of observational facilities have been dedicated to measuring the physical properties of this object. These observations have provided astrometry to refine the orbital solution, photometry to measure the color, a rotation period and secular light curve, and spectroscopy to characterize the composition of the coma. Here, we report precovery photometry of 3I/ATLAS as observed with NASA's Transiting Exoplanet Survey Satellite (TESS). 3I/ATLAS was observed nearly continuously by TESS from UT 2025 May 7 to 2025 June 2. We use the shift-stack method to create deepstack images to recover the object. These composite images reveal that 3I/ATLAS has an average TESS magnitude of Tmag = 20.83 ± 0.05, 19.28 ± 0.05 and an absolute visual magnitude of HV = 13.72 ± 0.35;12.52 ± 0.35, the latter being consistent with magnitudes reported in 2025 July. When coupled with recent Hubble Space Telescope images deriving a nucleus size of R &lt; 2.8 km (H &gt; 15.4), our measurements suggest that 3I/ATLAS may have been active out at ∼6 au. Additionally, we extract a ∼20 day light curve and find no statistically significant evidence of a nucleus rotation period. Nevertheless, the data presented here are some of the earliest precovery images of 3I/ATLAS and may be used in conjunction with future observations to constrain the properties of our third interstellar interloper.

Keywords: Comets, Asteroids, Interstellar objects, Photometry