Sazuna/UAT_keywords huggingface dataset:
A Necessary Condition for the Submergence of Proto─Neutron Star Magnetic Fields by Supernova Fallback. Central compact objects (CCOs) are a subclass of neutron stars (NSs) with a dipole magnetic field strength considerably weaker than those of radio pulsars and magnetars. One possible explanation for such weak magnetic fields in the CCOs is the hidden magnetic field scenario, in which supernova fallback submerges the magnetosphere of a proto-NS (PNS) beneath a newly formed crust. However, the fallback mass and timescale required for this submergence process remain uncertain. We perform one-dimensional general relativistic magnetohydrodynamic simulations of the supernova fallback onto a magnetized PNS, while considering neutrino cooling. In our simulations, the infalling material compresses the magnetic field and drives a strong shock. The shock initially expands outward, but eventually stalls and recedes as neutrino cooling becomes significant. After the shock stalls, the gas density above the magnetosphere increases rapidly, potentially leading to the formation of a new crust. To understand the shock dynamics, we develop semianalytic models that describe the resulting magnetospheric and shock radii when the shock stalls. By comparing the fallback timescale with the shock stalling timescale, corresponding to the waiting time for the new crust formation, we derive a necessary condition for the submergence of the PNS's magnetic field. Our results will provide guidance for investigating the diversity of young isolated NSs through multidimensional simulations.

Keywords: Neutron stars, Accretion, Supernova neutrinos, Core-collapse supernovae, High energy astrophysics, General relativity, Magnetohydrodynamical simulations
Hemispheric Magnetic Asymmetry and Cross-equatorial Circulation Cells within the Sun's Near-surface Shear Layer. Using time─distance helioseismic measurements of meridional flow in the near-surface shear layer over a period of 14 yr starting from 2010 May, we probe the depth structure and evolution of its cross-equatorial part. We confirm that the hemispheric magnetic asymmetry determines the amplitude and direction of such flows. Additionally, we find that these flows turn over and change direction at depths below 0.97R⊙ forming circulation cells with lifetimes dictated again by the hemispheric magnetic imbalance, which is dominated by the occurrences of large sunspots. We also examine connections between cross-equatorial magnetic flux plumes and flows and discuss their implications for the equatorial flux cancellation/submergence and the poleward transport of flux.

Keywords: Solar interior, Helioseismology, Solar convective zone, The Sun, Sunspots, Solar physics, Solar meridional circulation
Evolution Models of CO White Dwarf─Asymptotic Giant Branch Star Merger Remnants. Common envelope evolution is a critical but still poorly understood phase in binary evolution. It plays a key role in forming close binaries such as hot subdwarfs, double white dwarfs (WDs), X-ray binaries, and double neutron stars. However, its outcomes remain highly uncertain. Depending on the efficiency of envelope ejection, a system may either survive as a close binary or undergo a complete merger. In this work, we investigate the postmerger evolution of systems where a CO WD merges with the core of an asymptotic giant branch (AGB) star. A grid of merger remnant models with various core and envelope masses is constructed. At the onset of evolution, the CO core contracts and undergoes off-center carbon ignition, producing an inwardly propagating carbon flame. For remnants with a relatively low mass of CO core, the flame phase is followed by core contraction and subsequent H shell burning. For more massive CO cores, the carbon flame reaches the center and is soon followed by off-center neon burning, which is expected to eventually lead to core-collapse supernovae. The merger remnants occupy nearly the same region on the H-R diagram as ordinary AGB or super-AGB stars, exhibiting similar surface properties. Although their surface abundance may differ slightly from those of normal AGB stars, depending on the initial core and envelope masses, these differences are strongly reduced once mass loss is taken into account. We suggest that some giant-like stars, including candidates for Thorne─Żytkow objects (e.g., HV 2112), might alternatively be explained as AGB─WD merger remnants.

Keywords: White dwarf stars, Asymptotic giant branch stars, Stellar mergers, Common envelope binary stars
Revealing Hidden Cosmic Flows through the Zone of Avoidance with Deep Learning. We present a refined deep-learning-based method to reconstruct the 3D dark matter density, gravitational potential, and peculiar velocity fields in the Zone of Avoidance (ZOA), a region near the Galactic plane with limited observational data. Using a convolutional neural network (V-Net) trained on A-SIM simulation data, our approach reconstructs density or potential fields from galaxy positions and radial peculiar velocities. The full 3D peculiar velocity field is then derived from the reconstructed potential. We validate the method with mocks that mimic the spatial distribution of the Cosmicflows-4 (CF4) catalog and apply it to actual data. Given CF4's significant observational uncertainties and since our model does not yet account for them, we use peculiar velocities corrected via an existing Hamiltonian Monte Carlo reconstruction, rather than raw catalog distances. Our results demonstrate that the reconstructed density field recovers known galaxy clusters detected in an H I survey of the ZOA, despite this dataset not being used in the reconstruction. This agreement underscores the potential of our method to reveal structures in data-sparse regions. Most notably, streamline convergence and watershed analysis identify a mass concentration consistent with the Great Attractor, at (l, b) = (308 .° 4 ± 2 .° 4, 29 .° 0 ± 1 .° 9) and cz = 4960.1 ± 404.4 km s−1, for 64% of realizations. Our method is particularly valuable as it does not rely on data point density, enabling accurate reconstruction in data-sparse regions and offering strong potential for future surveys with more extensive galaxy datasets.

Keywords: Great Attractor, Observational cosmology, Dark matter, Large-scale structure of the universe
What's the Buzz about GX 13+1? Constraining Coronal Geometry with QUEEN-BEE: A Bayesian Nested Sampling Framework for X-Ray Polarization Rotation Analysis. Observations from the Imaging X-ray Polarimetry Explorer (IXPE) have revealed electric vector position angle (EVPA) rotation in several neutron star low-mass X-ray binaries, including the Galactic X-ray burster GX 13+1. We developed a novel Bayesian nested sampling framework—"Q-U Event-by-Event Nested sampling for Bayesian EVPA Evolution" (QUEEN-BEE)—to model the unbinned Stokes parameters and infer optimal EVPA rotation rates in IXPE data. We then applied this framework to three previous IXPE observations of GX 13+1. In the first observation, QUEEN-BEE recovers a rotation rate of 42° ± 4° day−1, consistent with prior binned analysis. Energy-binned QUEEN-BEE analysis of this first observation suggests a slablike coronal geometry, providing the first constraints between slab and shell coronae for this source. We also explore alternative EVPA rotation scenarios in GX 13+1, including variable disk wind behavior. The second observation of this source shows no evidence of rotation, and the third observation shows transient rotating behavior with an EVPA rotation rate when exiting a light curve dip of  170−40+20°  day−1. The results show marginal but consistent increases in the overall measured polarization degree for epochs where the EVPA rotation is identified. These results demonstrate that QUEEN-BEE can identify evolving polarization signatures in both time- and energy-resolved regimes, even where binned methods fall below detection thresholds. Our findings highlight the diagnostic potential of QUEEN-BEE as a tool for discriminating between competing physical models of coronal geometry and probing disk-wind-related polarization behavior, highlighting the promising potential for application of this framework in a variety of other IXPE observations.

Keywords: Neutron stars, Accretion, X-ray astronomy, X-ray binary stars, Bayesian statistics, Astrostatistics, Polarimetry
The Large-scale Environments of Low-luminosity AGNs at 3.9 &lt; z &lt; 6 and Implications for Their Host Dark Matter Halos from a Complete NIRCam Grism Redshift Survey. We study the large-scale environments and clustering properties of 28 low-luminosity active galactic nuclei (AGNs) at z = 3.9─6 in the GOODS-N field. Our sample, identified from the JWST NIRCam Imaging and WFSS data in Complete NIRCam Grism Redshift Survey and First Reionization Epoch Spectroscopically Complete Observations surveys with either broad Hα emission lines or V-shaped continua, are compared to 782 Hα emitters (HAEs) selected from the same data. These AGNs are located in diverse large-scale environments and do not preferentially reside in denser environments compared to HAEs. Their overdensity field, δ, averaged over (15 h−1 cMpc)3, ranges from −0.56 to 10.56, and shows no clear correlation with broad-line luminosity, black hole (BH) masses, or the AGN fraction. It suggests that &gt;10 cMpc structures do not significantly influence BH growth. We measure the two-point cross-correlation function of AGNs with HAEs, finding a comparable amplitude to that of the HAE autocorrelation. This indicates similar bias parameters and host dark matter halo masses for AGNs and HAEs. The correlation length of field AGNs is 4.26 h−1 cMpc and 7.66 h−1 cMpc at 3.9 &lt; z &lt; 5 and 5 &lt; z &lt; 6, respectively. We infer a median host dark matter halo mass of  log(Mh/M⊙)≍11.0−11.2  and host stellar masses of  log(M⋆/M⊙)≍8.4─8.6  by comparing with the UNIVERSEMACHINE simulation. Our clustering analysis suggests that low-luminosity AGNs at high redshift reside in normal star-forming galaxies with overmassive BHs. They represent an intrinsically distinct population from luminous quasars and could be a common phase in galaxy evolution.

Keywords: Supermassive black holes, Galaxy dark matter halos, James Webb Space Telescope, Low-luminosity active galactic nuclei, Active galactic nuclei, Clustering
Continuum Reverberation Mapping of 18 Active Galactic Nuclei over 4 Yr. Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). The source of this emission has long been thought to originate from the accretion disk, but recent studies suggest the broad-line region (BLR) may significantly contribute to both the observed flux and continuum interband delays. We monitored 18 AGN over 4 yr of observations to acquire high-quality optical continuum light curves, measuring time lags between different photometric bands and determining continuum emission sizes for each active galactic nucleus. We add this sample to existing lag measurements to test the correlation between continuum lags at 5100 Å (τ5100) and 5100 Å luminosity (L5100). We observe that  τ5100∝L51000.4 , broadly consistent with the theoretical expectations of τ ∝ L1/2 expected for continuum reverberation from either the accretion disk or the BLR.

Keywords: Optical astronomy, Supermassive black holes, Reverberation mapping, Active galactic nuclei
"Industrial-scale" Black Hole Selection without a Satellite. The forthcoming GRAVITY+ instrument promises to usher in an era of "industrial-scale" mass measurements of isolated black holes (BHs), with the potential to assemble a sample of many tens of BHs via interferometric microlensing over several years. A key challenge will be selecting interferometric follow-up targets from a 1 order of magnitude larger pool of ongoing microlensing events when using traditional selection based on event timescale alone. A. Gould proposed a criterion optimized for BH selection using space-based microlens parallax measurements enabled by a satellite. We adapt it to work with microlens parallax constraints obtainable from ground-based data only. Using Galactic simulations, we show that our selection criterion is highly efficient, expecting to detect about a dozen BHs per year with GRAVITY+ from following up ∼35 selected events.

Keywords: Gravitational microlensing, Optical interferometry, Stellar mass black holes, Microlensing parallax
Constraining the Jet Energetics of the Transient X-Ray Binaries MAXI J1348−630 and MAXI J1820+070 through Calorimetry. We present Atacama Large Millimeter/submillimeter Array observations aimed at identifying potential jet─interstellar medium (ISM) interaction sites in the vicinity of the transient black hole X-ray binaries MAXI J1348−630 and MAXI J1820+070, both of which have recently undergone an outburst, and displayed powerful large-scale jets. Using this dataset, we construct molecular line emission maps. By analyzing the morphological, spectral, and kinematic properties of the detected emission, we identify a molecular structure that provides compelling evidence for a jet-driven cavity in the local environment of MAXI J1348−630 but find no significant emission in the local environment of MAXI J1820+070. We use the properties of the detected molecular emission surrounding MAXI J1348−630 to constrain the jet power, finding our results to be consistent with other independent studies of this source, and further validating the utility of astrochemistry for constraining jet energetics. Additionally, our findings provide the first assessment on the formation timescales for jet─ISM interaction regions in the transient black hole X-ray binary population.

Keywords: Black hole physics, Jets, High energy astrophysics
Photo-z Estimation with Normalizing Flow. Accurate photometric redshift (photo-z) estimation is a key challenge in cosmology, as uncertainties in photo-z directly limit the scientific return of large-scale structure and weak lensing studies, especially in upcoming Stage IV surveys. The problem is particularly severe for faint galaxies with sparse spectroscopic training data. In this work, we introduce nflow-z, a novel photo-z estimation method using the powerful machine learning technique of normalizing flow. nflow-z explicitly models the redshift probability distribution conditioned on the observables such as fluxes and colors. We build two nflow-z implementations, dubbed cINN and cNSF, and compare their performance. We demonstrate the effectiveness of nflow-z on several datasets, including a CSST mock, the COSMOS2020 catalog, and samples from Dark Energy Survey (DES) Y1, the Sloan Digital Sky Survey, and DESCaLS. Our evaluation against state-of-the-art algorithms shows that nflow-z performs favorably. For instance, cNSF surpasses random forest, multilayer perceptron, and convolutional neural network on the CSST mock test. We also achieve a 30% improvement over official results for the faint DESCaLS sample and outperform conditional generative adversarial network and mixture density network methods on the DES Y1 dataset test. Furthermore, nflow-z is computationally efficient, requiring only a fraction of the computing time of some of the competing algorithms. Our algorithm is particularly effective for the faint sample with sparse training data, making it highly suitable for upcoming Stage IV surveys.

Keywords: Galaxy photometry, Redshift surveys, Photometry
Presupernova Multiple Giant Eruptions in Massive Stars. Massive stars can exhibit giant eruptions with high mass loss shortly before their explosion as a core-collapse supernova. These multiple giant eruptions (MGEs) may have a commutative effect that brings the star to a different state, possibly one that favors the explosion. To address this problem, we evolve a 100 M⊙ star and initiate a series of three giant eruptions lasting 1 year each, testing different mass-loss rates and different metallicities. Following each eruption, we track the recovery phase to examine the posteruption behavior of the star and its recovery timescale. The MGEs lead to a decrease in luminosity, accompanied by a slight increase in temperature. Later, during the recovery phases, as the star starts to retain its equilibrium state, its luminosity increases. The recovery timescale varies significantly after each eruption, independent of the mass-loss rate, but it is shorter for lower metallicities. For higher mass-loss rates during the recovery phase, the outer layers of the star exhibit oscillations and undergo compression at higher metallicity. These oscillations are most likely a consequence of thermal imbalance in the outer envelope. This behavior at higher mass-loss rates also suggests that thermal readjustments during recovery may create favorable conditions for a subsequent eruption of the star.

Keywords: Massive stars, Stellar winds, Eruptive variable stars, Stellar mass loss
Uncertainty-aware Neural Networks for Fuzzy Dark Matter Model Selection from x<SUB>H I</SUB> Measurements. The nature of dark matter remains a central question in cosmology, with fuzzy dark matter (FDM) models offering a compelling alternative to the cold dark matter paradigm. We explore FDM scenarios by performing 21 cm simulations across a parameter space with fFDM ∈ [0.02, 0.10] and mFDM ∈ [10−24, 10−21] eV, obtaining global neutral hydrogen fractions (xH I) for each model. Observational xH I data and associated uncertainties from the James Webb Space Telescope are incorporated by estimating full probability density functions (pdfs) for both xH I and redshift z using Bayesian inference with the No-U-Turn Sampler, yielding non-Gaussian multivariate uncertainty distributions. A hybrid machine learning framework is then trained on these observational pdfs to learn both central values and correlated uncertainties in xH I and z, iteratively refining its parameters in each training epoch through direct incorporation of the multivariate pdfs derived from observational constraints. We then compare the simulation outputs to the machine-learned observational trends to identify the most consistent models. Our results indicate that FDM models with mFDM ≃ 10−22 eV and fFDM ≃ 0.04 best match the current data, while lighter masses are strongly constrained. By integrating simulations and machine learning in an uncertainty-aware framework, this work explores the physics of the early Universe and guides future studies of 21 cm cosmology and reionization.

Keywords: Neural networks, James Webb Space Telescope, Bayesian statistics, Intergalactic medium
Spatially Resolved, Multiphase Mass Outflows of the Seyfert 1 Galaxy NGC 3227. We present spatially resolved mass outflow rates of the ionized and molecular gas in the narrow-line region of the Seyfert 1 galaxy NGC 3227. Using long-slit spectroscopy and [O III] imaging from from the Hubble Space Telescope's Space Telescope Imaging Spectrograph and Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph, in conjunction with Cloudy photoionization models and emission-line diagnostics, we find a peak ionized mass outflow rate of  Ṁion=  19.9 ± 9.2 M⊙ yr−1 at a distance of 47 ± 6 pc from the supermassive black hole (SMBH). Using archival data from the Gemini-North Near-infrared Field Spectrograph measuring H2 2.1218 μm emission, we find a maximum peak warm molecular outflow rate of  ṀH2≤9×10−4  M⊙ yr−1 at a distance of 36 ± 6 pc from the SMBH. Using archival data from the Atacama Large Millimeter/submillimeter Array measuring CO(2─1) emission, we find a maximum peak cold molecular gas mass outflow rate of  ṀCO≤  23.1 M⊙ yr−1 at a distance of 57 ± 6 pc from the SMBH. For the first time, we calculate spatially resolved gas evacuation timescales for the cold molecular gas reservoirs ostensibly sourcing the outflows, and find that gas evacuating to ∼400 pc from the SMBH occurs on timescales of 106.0─107.6 yr. These results indicate that the multiphase active galactic nucleus (AGN) outflows are effective in clearing the inner few hundred parsecs of NGC 3227's gas content on timescales that may set the AGN duty cycle of 105─108 yr.

Keywords: AGN host galaxies, Supermassive black holes, Emission line galaxies, Seyfert galaxies, Active galactic nuclei, Galaxy winds, Galaxy kinematics
Validation of Linear Polarization Tomographic Inversion for the 3D Reconstruction of the Solar Coronal Magnetic Fields. This paper presents a quantitative assessment of the accuracy of the linear polarization (LP) tomographic inversion algorithm for the reconstruction of the 3D coronal magnetic fields. A magnetohydrodynamic model of the solar corona during solar minimum generated by Predictive Science, Inc. was used to synthesize LP (Stokes-Q and -U) observations of the Fe XIII 1075 nm coronal emission line produced by the saturated Hanle effect. The synthetic measurements are made by an observer situated at the solar equatorial plane and from 72 viewing directions with a 5∘ separation spanning over a range of 180∘ in Carrington longitude. We did not introduce noise in the data and did not consider discretization errors. This allows us to study an ideal case, i.e., to show whether it is possible at all to get a better solution than the Potential Field with Source Surface (PFSS) model. The inversion results show that the LP tomography outperforms the PFSS model in reconstruction of the both magnetic field strength and direction.

Keywords: Remote sensing, Spectropolarimetry, Solar corona, Magnetic fields
On the Divergent Evolution of Io and Europa as Primordial Ocean Worlds. The Galilean moons exhibit a decrease in bulk density with distance from Jupiter, which may reflect differences in evolutionary paths and water loss. Early in its history, Jupiter was more luminous, which may have driven substantial atmospheric escape on Io and Europa. We investigate whether Io could have lost its water inventory while Europa retained its volatiles, assuming both moons initially accreted hydrous silicates. The formation and early thermal evolution of the protosatellites are modeled using an interior evolution model coupled with an atmospheric escape framework. Dehydration timescales and volatile losses for Io and Europa are computed during their early evolution, accounting for accretional heating from both satellitesimal and pebble accretion and irradiation from Jupiter's primordial luminosity. Europa likely retained most of its volatiles under nearly all plausible formation and evolution scenarios, as large-scale dehydration would have taken place only after the first ∼10 Myr of its evolution. In contrast, Io was unlikely to lose a substantial amount of water through atmospheric escape and therefore probably accreted predominantly anhydrous silicates. If Europa initially accreted hydrous minerals, the present-day volatile contrast between Io and Europa could be explained by their relative locations with respect to the phyllosilicate dehydration line in the Jovian subnebula. Distinct evolutionary pathways or atmospheric escape processes alone appear insufficient to reproduce the observed differences.

Keywords: Natural satellite formation, Jupiter, Europa, Io, Galilean satellites, Atmospheric dynamics