Sazuna/UAT_keywords huggingface dataset:
Toward High-order Solar Corona Simulations: A High-order Hyperbolized Poisson Approach for Magnetic Field Initialization. Proper initialization of the solar corona magnetic field is important for easing the iterative process of realistic and efficient global magnetohydrodynamics (MHD) simulations. This study introduces a high-order flux reconstruction (FR) framework for solving the Poisson equation, a necessary step for computing a potential-field source-surface (PFSS) to initialize the magnetic field for global solar corona simulations with MHD. By hyperbolizing the elliptic Poisson equation into a set of hyperbolic equations, we develop an efficient and robust high-order PFSS solver. Our contributions include developing a Q2 (i.e., quadratic) geometrical representation using prismatic elements for the computational domain, which enables high-order mesh generation. Such a hyperbolized Poisson solver effectively relaxes magnetic fields extrapolated from solar magnetograms, producing scalar potential fields that align well with theoretical expectations. Extensive verification was conducted on the high-order FR solver for polynomial orders up to P3, achieving fourth-order spatial accuracy. The hyperbolized solver demonstrates comparable accuracy to reference solutions (both analytical and numerical) while offering efficient performance, particularly on coarser meshes, making it competitive with state-of-the-art low-order finite volume solvers, which are mostly used for solar MHD simulations. The described developments are a milestone for enabling high-order global solar corona simulations on 3D unstructured grids.

Keywords: Space weather, Computational methods, Solar corona
Search for Neutrino Signals Correlated with LHAASO Diffuse Galactic Emission. The diffuse Galactic γ-ray emission originates from the interactions between cosmic rays and the interstellar medium or radiation fields within our Galaxy, where the production of neutrinos is also anticipated. Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported measurements of diffuse γ-rays from the Galactic plane with energies ranging from sub-TeV to 1 PeV. Using 7 yr of publicly available IceCube track data with the full detector, we conduct a template search using the γ-ray flux map observed by LHAASO-KM2A as the neutrino emission template and perform a scan search of the Galactic plane. In the template search, a mild excess of neutrinos is observed in the Galactic plane with a pretrial (posttrial) significance of 1.9σ (1.1σ). The measured muon neutrino intensity at 25 TeV is  , consistent with the expected neutrino flux assuming that all the diffuse Galactic γ-rays originate from hadronic interactions. In the Galactic plane scan search, the most significant location is found at l = 63 57 and b = 0 93 with a pretrial (posttrial) significance of 4.6σ (1.8σ).

Keywords: Galactic cosmic rays, Gamma-ray astronomy, Neutrino astronomy
Bayesian Pulsar Timing and Noise Analysis with Vela.jl: An Overview. We present Vela.jl, an efficient, modular, easy-to-use Bayesian pulsar timing and noise analysis package written in Julia. Vela.jl provides an independent, efficient, and parallelized implementation of the full nonlinear pulsar timing and noise model along with a Python binding named pyvela. One-time operations such as data file input, clock corrections, and solar system ephemeris computations are performed by pyvela with the help of the PINT pulsar timing package. Its reliability is ensured via careful design utilizing Julia's type system, strict version control, and an exhaustive test suite. This paper describes the design and usage of Vela.jl focusing on the narrowband paradigm.

Keywords: Astronomy data analysis, Astronomy software, Pulsars
Magnetized Protoplanetary Disks around Young Stars in the Presence of Realistic Cooling. In this paper, we study the effects of magnetic fields and ohmic resistivity on the structure of protoplanetary disks (PPDs) in the presence of realistic radiative cooling. We use the self-similar method to solve the magnetohydrodynamic equations in spherical coordinates (r, θ, ϕ). Our solutions indicate that a strong magnetic field reduces the outflow region while increasing the mass accretion rate, which in turn leads to a thicker disk. Our model applied to the FU Orionis PPD indicates that in the inner regions of the disk (r = 10 au),   is the order of   and the mass outflow rate is  , which is consistent with the observed range of accretion rates. Additionally, we calculated the cooling timescale in our model to assess one possible fragmentation condition necessary for planet formation. Our results indicate that, although the gravitational instability condition exists in the midplane of the disk, the cooling timescale is not short enough (τcool ≈ 1000Ω‑1), and one possible mechanism for planet formation is not met.

Keywords: Protostars, Magnetic fields, Protoplanetary disks
Nonthermal Signatures of Radiative Supernova Remnants. II. The Impact of Cosmic Rays and Magnetic Fields. Near the ends of their lives, supernova remnants (SNRs) enter a "radiative phase," when efficient cooling of the postshock gas slows expansion. Understanding SNR evolution at this stage is crucial for estimating feedback in galaxies, as SNRs are expected to release energy and momentum into the interstellar medium near the ends of their lives. A standard prediction of SNR evolutionary models is that the onset of the radiative stage precipitates the formation of a dense shell behind the forward shock. In Paper I, we showed that such shell formation yields detectable nonthermal radiation from radio to γ-rays, most notably emission brightening by nearly 2 orders of magnitude. However, there remains no observational evidence for such brightening, suggesting that this standard prediction needs to be investigated. In this paper, we perform magnetohydrodynamic simulations of SNR evolution through the radiative stage, including cosmic rays (CRs) and magnetic fields to assess their dynamical roles. We find that both sources of nonthermal pressure impede shell formation, reducing shell densities by a factor of a few to more than an order of magnitude. We also use a self-consistent model of particle acceleration to estimate the nonthermal emission from these modified SNRs and demonstrate that, for reasonable CR acceleration efficiencies and magnetic field strengths, the nonthermal signatures of shell formation can all but disappear. We therefore conclude that the absence of observational signatures of shell formation represents strong evidence that nonthermal pressures from CRs and magnetic fields play a critical dynamical role in late-stage SNR evolution.

Keywords: Stellar feedback, Galactic radio sources, Gamma-ray sources, Galactic cosmic rays, Supernova remnants, Shocks, Magnetic fields, Cosmic rays
Improved SED-fitting Assumptions Result in Inside-out Quenching at z ~ 0.5 and Quenching at All Radii Simultaneously at z ~ 1. Many studies conclude that galaxies quench from the inside-out by examining profiles of specific star formation rate (sSFR). These are usually measured by fitting spectral energy distributions (SEDs) assuming a fixed dust law and uniform priors on all parameters. Here, we examine the effects of more physically motivated priors: a flexible dust law, an exponential prior on the dust attenuation AV, and Gaussian priors that favor extended star formation histories. This results in model colors that better trace observations. We then perform radial SED fits to multiband flux profiles measured from Hubble Space Telescope images for 1440 galaxies at 0.4 &lt; z &lt; 1.5 of stellar masses 1010–1011.5M⊙ using both the traditional and the more physically motivated assumptions. The latter results in star formation rate and AV profiles that agree with measurements from spectroscopy and AV profiles that behave correctly as a function of inclination. Since green valley galaxies at z ∼ 1.3 are expected to evolve into quiescent galaxies at z ∼ 0.9, we compare their sSFR profiles using the more physically motivated assumptions. Their slopes are similar at all masses (0.06–0.08 dex kpc‑1), and the normalizations for the quiescent galaxies are lower. Therefore, the sSFR profiles decline with time as quenching occurs at all radii simultaneously. We compare profiles of green valley galaxies at z ∼ 0.9 and quiescent galaxies at z ∼ 0.5. The former are shallower at all masses by ~0.1 dex kpc‑1. The sSFR profiles steepen with time as galaxies quench from the inside-out. In summary, galaxies at z ∼ 1 quench at all radii simultaneously while galaxies at z ∼ 0.7 quench from the inside-out.

Keywords: Galaxy quenching, Spectral energy distribution, Galaxy evolution
The Secondary Component of the Extremely Low Mass Ratio Massive Binary HD 165246 Revealed by GHOST. In the pursuit of understanding the multiplicity of massive stars, the OWN Survey has undertaken spectroscopic monitoring of hundreds of targets over the past 20 yr. This effort has led to the discovery of new single-lined spectroscopic binaries. Characterizing the unseen companions of these systems is crucial to deriving precise stellar parameters, including the mass of each component, and constraining formation models for massive binary systems. In this paper, we aim to physically and evolutionarily characterize the stellar components of the massive binary HD 165246. We analyzed spectra obtained by the OWN Survey and used Kepler's second mission (K2) photometry, from which we determined the physical parameters of the system. Thanks to the high-resolution capabilities of the new echelle spectrograph Gemini/GHOST, we could directly detect spectral features of the secondary component for the first time. A very low mass ratio for the system is confirmed (q ~ 0.16), making this binary one of the few extremely low mass ratio systems known. The primary star has a mass of Ma = 22 ± 1 M⊙ and a radius of Ra = 7.0 ± 0.1 R⊙, while the secondary star has a mass of Mb = 3.4 ± 0.1 M⊙ and a radius of Rb = 2.22 ± 0.02 R⊙. Stellar evolution models indicate that the system has undergone approximately two million years of evolution since its formation. Moreover, the secondary star is identified as a pre-main-sequence object, progressing toward the zero-age main sequence. This paper illustrates the power of high-resolution spectrographs such as GHOST in finding much lower mass, previously unseen stellar components of binary star systems.

Keywords: Early-type stars, Fundamental parameters of stars, Close binary stars, Massive stars, Eclipsing binary stars
Hubble Space Telescope Observations within the Sphere of Influence of the Powerful Supermassive Black Hole in PKS 0745-191. We present Space Telescope Imaging Spectrograph observations from the Hubble Space Telescope of the supermassive black hole (SMBH) at the center of PKS 0745-191, a brightest cluster galaxy (BCG) undergoing powerful radio-mode active galactic nucleus (AGN) feedback (Pcav ~ 5 × 1045 erg s‑1). These high-resolution data offer the first spatially resolved map of gas dynamics within an SMBH's sphere of influence under such powerful feedback. Our results reveal the presence of highly chaotic, nondrotational ionized gas flows on subkiloparsec scales, in contrast to the more coherent flows observed on larger scales. While radio-mode feedback effectively thermalizes hot gas in galaxy clusters on kiloparsec scales, within the core, the hot gas flow may decouple, leading to a reduction in angular momentum and supplying ionized gas through cooling, which could enhance accretion onto the SMBH. This process could, in turn, lead to a self-regulating feedback loop. Compared to other BCGs with weaker radio-mode feedback, where rotation is more stable, intense feedback may lead to more chaotic flows, indicating a stronger coupling between jet activity and gas dynamics. Additionally, we observe a sharp increase in velocity dispersion near the nucleus, consistent with a very massive MBH ~ 1.5 × 1010 M⊙ SMBH. The density profile of the ionized gas is also notably flat, paralleling the profiles observed in X-ray gas around galaxies where the Bondi radius is resolved. These results provide valuable insights into the complex mechanisms driving galaxy evolution, highlighting the intricate relationship between SMBH fueling and AGN feedback within the host galaxy.

Keywords: Galaxy clusters, Supermassive black holes, Hubble Space Telescope, Galaxy nuclei, Galaxy kinematics, Spectroscopy, Radio active galactic nuclei, Brightest cluster galaxies
MUSEQuBES: Connecting H I Absorption with Lyα Emitters at z ≍ 3.3. We present a comprehensive analysis of H I absorption around 96 Lyα emitters (LAEs) at z ≍ 3.3 (median Lyα luminosity ≍1042 erg s−1). These LAEs were identified within eight MUSE fields, each   on the sky and centered on a bright background quasar, as part of the MUSEQuBES survey. Using Voigt profile fitting for all H I absorbers detected within ±500 km s−1 of these LAEs, we compiled a catalog of 800 H I absorption components. Our analysis shows that H I absorption is enhanced near the LAEs compared to the intergalactic medium. However, no trend is found between the column densities of H I absorbers and their impact parameters from the LAEs (spanning ≍54─260 pkpc). Additionally, all galaxies associated with Lyman-limit systems have impact parameters &gt;50 pkpc from the quasar sightlines, suggesting that true absorber hosts may be too faint to detect. The LAEs show an overall H I covering fraction (fc(H I)) of ≍88% for a threshold  (H I) = 15. Notably, at the same threshold, the LAEs in pairs/groups exhibit a 100% H I covering fraction out to ≍250 pkpc. In contrast, isolated LAEs consistently show a lower fc(H I) of ≍80%. This environmental influence on fc(H I) is also evident up to ≍300 km s−1 in differential bins of line-of-sight velocity. We find an anticorrelation between fc(H I) and the equivalent width of rest-frame Lyα emission (EW0). Based on the Lyα shell model, this could imply that gas-rich galaxies tend to reside in gas-rich environments or that the LAEs with higher EW0 are more efficient at ionizing their surrounding medium.

Keywords: Lyman-alpha galaxies, Galaxy evolution, Quasar absorption line spectroscopy, Circumgalactic medium
LensWatch. II. Improved Photometry and Time-delay Constraints on the Strongly Lensed Type Ia Supernova 2022qmx ("SN Zwicky") with Hubble Space Telescope Template Observations. Strongly lensed supernovae (SNe) are a rare class of transient that can offer tight cosmological constraints that are complementary to methods from other astronomical events. We present a follow-up study of one recently discovered strongly lensed SN, the quadruply imaged type Ia SN 2022qmx (aka "SN Zwicky"), at z = 0.3544. We measure updated, template-subtracted photometry for SN Zwicky and derive improved time delays and magnifications. This is possible because SNe are transient, fading away after reaching their peak brightness. Specifically, we measure point-spread-function photometry for all four images of SN Zwicky in three Hubble Space Telescope WFC3/UVIS passbands (F475W, F625W, and F814W) and one WFC3/IR passband (F160W), with template images taken ∼11 months after the epoch in which the SN images appear. We find consistency to within 2σ between lens-model-predicted time delays (≲1 day) and measured time delays with HST colors (≲2 days), including the uncertainty from chromatic microlensing that may arise from stars in the lensing galaxy. The standardizable nature of SNe Ia allows us to estimate absolute magnifications for the four images, with images A and C being elevated in magnification compared to lens model predictions by about 6σ and 3σ, respectively, confirming previous work. We show that millilensing or differential dust extinction is unable to explain these discrepancies, and we find evidence for the existence of microlensing in images A, C, and potentially D that may contribute to the anomalous magnification.

Keywords: Cosmology, High energy astrophysics, Strong gravitational lensing, Type Ia supernovae, Supernovae
Solar Variability in the Mg II h and k Lines. Solar irradiance and its variations in the ultraviolet (UV) control the photochemistry in Earth's atmosphere and influence Earth's climate. The variability in the Mg II h and k core-to-wing ratio, also known as the Mg II index, is highly correlated with the solar UV irradiance variability. Because of this, the Mg II index is routinely used as a proxy for solar UV irradiance variability, which can help to get insights into the influence of solar UV irradiance variability on Earth's climate. Measurements of the Mg II index, however, have only been carried out since 1978 and do not cover climate-relevant timescales longer than a few decades. Here we present a model to calculate the Mg II index and its variability based on the well-established Spectral And Total Irradiance REconstruction (SATIRE) model. We demonstrate that our model calculations yield an excellent agreement with the observed Mg II index variations, both on the solar activity cycle and on the solar rotation timescales. Using this model, we synthesize the Mg II index time series on climate-relevant timescales of decades and longer. Here we present the time series of the Mg II index spanning nearly three centuries.

Keywords: Solar ultraviolet emission, Plages, Solar transition region, Solar activity, Solar chromosphere
Comprehensive Parameter Determination of Exoplanets through Asteroseismic Host Star Constraints. This study develops a robust framework for exoplanet characterization by leveraging asteroseismic constraints on host stars. Using precise photometric data from missions such as Kepler and TESS, we derive stellar parameters, including mass, radius, and age, with high accuracy through asteroseismic analysis. These stellar parameters are incorporated as priors in a Bayesian framework to refine planetary properties such as the mass, radius, and orbital parameters. By applying Markov Chain Monte Carlo methods, we extract posterior distributions of planetary parameters, achieving significant improvements in precision and reliability. This approach is particularly effective for systems with evolved host stars, where precise stellar properties are essential for resolving uncertainties in planetary characterization. The results demonstrate the importance of asteroseismology in bridging stellar astrophysics and exoplanet science, enabling detailed studies of planetary system architectures and their dependence on host star properties. Our methodology underscores the synergy between stellar and planetary studies, paving the way for future research on exoplanet populations. This work provides a foundation for utilizing data from upcoming missions like PLATO, ensuring continued advancements in the precision and scope of exoplanet characterization.

Keywords: Red giant stars, Planet hosting stars, Radial velocity, Transit photometry, Asteroseismology
Flat U-Net: An Efficient Ultralightweight Model for Solar Filament Segmentation in Full-disk Hα Images. Solar filaments are one of the most prominent features observed on the Sun, and their evolutions are closely related to various solar activities, such as flares and coronal mass ejections. Real-time automated identification of solar filaments is the most effective approach to managing large volumes of data. Existing models of filament identification are characterized by large parameter sizes and high computational costs, which limit their future applications in highly integrated and intelligent ground-based and space-borne observation devices. Consequently, the design of more lightweight models will facilitate the advancement of intelligent observation equipment. In this study, we introduce Flat U-Net, a novel and highly efficient ultralightweight model that incorporates simplified channel attention (SCA) and channel self-attention (CSA) convolutional blocks for the segmentation of solar filaments in full-disk Hα images. Feature information from each network layer is fully extracted to reconstruct interchannel feature representations. Each block effectively optimizes the channel features from the previous layer, significantly reducing parameters. The network architecture presents an elegant flattening, improving its efficiency, and simplifying the overall design. Experimental validation demonstrates that a model composed of pure SCAs achieves a precision of approximately 0.93, with dice similarity coefficient (DSC) and recall rates of 0.76 and 0.64, respectively, significantly outperforming the classical U-Net. Introducing a certain number of CSA blocks improves the DSC and recall rates to 0.82 and 0.74, respectively, which demonstrates a pronounced advantage, particularly concerning model weight size and detection effectiveness. The data set, models, and code are available as open-source resources.

Keywords: Solar activity, Convolutional neural networks, Solar filaments, Astronomy image processing
Prediction of Star Formation Rates Using an Artificial Neural Network. In this study we develop an artificial neural network to estimate the infrared (IR) luminosity and star formation rates (SFR) of galaxies. Our network is trained using "true" IR luminosity values derived from modeling the IR spectral energy distributions of FIR-detected galaxies. We explore five different sets of input features, each incorporating optical, mid-infrared, near-infrared, ultraviolet, and emission line data, along with spectroscopic redshifts and uncertainties. All feature sets yield similar IR luminosity predictions, but including all photometric data leads to slightly improved performance. This suggests that comprehensive photometric information enhances the accuracy of our predictions. Our network is applied to a sample of SDSS galaxies defined as unseen data, and the results are compared with three published catalogs of SFRs. Overall, our network demonstrates excellent performance for star-forming galaxies, while we observe discrepancies in composite and AGN samples. These inconsistencies may stem from uncertainties inherent in the compared catalogs or potential limitations in the performance of our network.

Keywords: Galaxies
Toward Early-type Eclipsing Binaries as Extragalactic Milestones. IV. Physical Properties of Three Detached O/B-type Systems in the LMC. We present a complete set of physical parameters for three early-type eclipsing binary systems in the Large Magellanic Cloud (LMC): OGLE LMC-ECL-17660, OGLE LMC-ECL-18794, and HV 2274, together with the orbital solutions. The first and third systems comprise B-type stars, while the second has O-type components and exhibits a total eclipse. We performed a complex analysis that included modeling light and radial velocity curves, O − C analysis, and additional non-LTE spectroscopic analysis for the O-type system. We found that OGLE LMC-ECL-17660 is at least a triple, and tentatively, a quadruple. A significant nonlinear period decrease was determined for HV 2274. Its origin is unclear, possibly due to a faint, low-mass companion on a wide orbit. The analyzed components have masses ranging from 11.7 M⊙ to 22.1 M⊙, radii from 7.0 R⊙ to 14.2 R⊙, and temperatures between 22,500 and 36,000 K. For HV 2274, the precision of our masses and radii is about six times higher than in previous studies. The position of the components of all six systems analyzed in this series on the mass─luminosity and mass─radius diagrams indicates they are evolutionarily advanced on the main sequence. Our sample contributes significantly to the knowledge of physical parameters of early-type stars in the mass range of 11 M⊙─23 M⊙. A new mass─luminosity relation for O- and B-type stars in the LMC is provided. Additionally, we used the measured apsidal motion of the systems to compare the observational and theoretical internal structure constant.

Keywords: Early-type stars, Multiple stars, B stars, Binary stars, O stars, Apsidal motion, Fundamental parameters of stars, Large Magellanic Cloud, Detached binary stars, Eclipsing binary stars, Trinary stars