Sazuna/UAT_keywords huggingface dataset:
The Extent of Solar Energetic Particle Irradiation in the Sun's Protoplanetary Disk. Solar flares emit X-rays and high-energy (MeV to GeV) ions called solar energetic particles (SEPs). Astronomical observations show solar-mass protostellar fluxes are a factor Φ ≍ 3 × 102─3 × 103 times higher than the present-day Sun. Constraining Φ in the early solar system is important for modeling ionization in the Sun's protoplanetary disk, the extent of magnetorotational instability or magnetocentrifugal outflows, or even production of short-lived radionuclides. Recent interpretations of meteoritic data—including cosmogenic Ne in hibonite grains, initial  (10Be/9Be)0  ratios in Ca-rich, Al-rich inclusions (CAIs), or even inferences of live 7Be in CAIs—suggest values Φ &gt; 105, reaching as high as Φ ≍ 6 × 106, which would make the young Sun extraordinarily active, even for a protostar. We constrain Φ by reexamining these data. We conclude that cosmogenic Ne was produced in hibonite grains as they resided in the disk; 36Cl was created in Cl-poor grains after the disk dissipated; 10Be was inherited from the molecular cloud, with almost no (&lt;1%) 10Be created in the disk; and there is no evidence whatsoever for any live 7Be in CAIs. We show these data are consistent with a value Φ ≍ 3 × 103 for the first &gt;5 Myr of the solar nebula. The early Sun evidently emitted a flux of X-rays and SEPs not atypical for a protostar.

Keywords: Solar flares, Cosmic ray nucleosynthesis, Protoplanetary disks, Meteorites, Protostars
The Optical Evolution of Tycho's Supernova Remnant over Three Decades. We report a series of images of Tycho's supernova remnant at eight epochs extending over 30 yr: 1986─2016. In addition to our Hα images, we have obtained matched continuum images, which we subtract to reveal faint emission, including a far more extensive network of optical knots and filaments than reported previously. The deepest images also show an extremely faint, fairly diffuse arc of emission surrounding much of the circumference of Tycho to the southeast and south, coinciding with the rim of the radio and X-ray shell. We have measured proper motions for 46 filaments, including many fainter ones near Tycho's outer rim. Our measurements are generally consistent with previous ones by K. W. Kamper &amp; S. van den Bergh, but ours have far greater precision. Most optical filaments at the shell rim have expansion indices reasonably consistent with the Sedov value (0.40), while the interior filaments have somewhat smaller values, as expected. From the combination of the proper motions of the filaments at the shell rim and the shock velocity at the same positions, one should be able to calculate the distance to Tycho by simple geometry. Determination of the shock velocity from broad Balmer-line profiles is subject to model uncertainties, but the availability of dozens of such filaments with a range of conditions offers the possibility to substantially improve the distance determination for Tycho. *Dedicated to the memory of Janet Winkler, who made it all fun throughout these decades.

Keywords: Supernova remnants, History of astronomy, Interstellar medium, Shocks, Supernovae
Evidence of an Energetic Magnetar Powering 1LHAASO J0500+4454. We investigate the origin of the unidentified, extended TeV source 1LHAASO J0500+4454, considering three possible origins: cosmic rays interacting with a molecular cloud (MC), particles accelerated in a currently undetected supernova remnant (SNR), and an energetic outflow powered by a pulsar. Upper limits on the CO and X-ray emission from the γ-ray emitting region disfavor the MC and SNR scenarios, respectively. If a nebula of inverse Compton scattering e±powers 1LHAASO J0500+4454, then spectral energy distribution modeling indicates that the current particle energy in the nebula is ∼4 × 1048 erg. If the coincident magnetar SGR 0501+4516's rotational energy powered 1LHAASO J0500+4454, then a conservative energy budget calculation requires an initial magnetar spin period P0 ≲ 5 ms and a spin-down timescale τsd ≲ 30 yr, which has implications for the origins of magnetars.

Keywords: Gamma-ray sources, Pulsars, Pulsar wind nebulae, Magnetars, Supernovae
Tentative Detection of Neutral Gas in a Little Red Dot at z = 4.46. JWST has revealed a population of broad-line active galactic nuclei at z &gt; 4 with remarkably red colors, so-called "Little Red Dots" (LRDs). Ubiquitous Balmer breaks suggest that they harbor old stellar populations in massive, compact host galaxies. We present Atacama Large Millimeter/submillimeter Array observations of three LRDs at z = 3.10, 4.46, and 7.04, targeting molecular and neutral gas via CO(7─6) and [C I](2─1), respectively. We do not detect CO in any target, placing conservative limits on the host molecular gas mass of ≲(1─5) × 1010 M⊙. We report the tentative (∼3.5σ) detection of the [C I](2─1) line in A2744-45924 (z = 4.46), one of the brightest known LRDs. The [C I] line is narrow (FWHM ∼ 80 km s−1), implying a dynamical mass ≲1010 M⊙, adopting conservative limits for the size of the galaxy. The dynamical mass limit is significantly lower than expected from the local MBH─Mdyn relation, and is an order of magnitude below the stellar mass derived from spectral energy distribution fitting, potentially supporting a nonstellar origin of the Balmer break. These results, while tentative, paint a picture of LRDs that is markedly different than typical high-z quasars, which live in massive, gas-rich, and actively star-forming host galaxies.

Keywords: AGN host galaxies, Supermassive black holes, Active galactic nuclei, Galaxy evolution, High-redshift galaxies
Resolving the Multiple Component Outflows in PG 1211+143. I. The Fe─K Absorption Structure and UFO Forest. We present the initial high-resolution X-ray spectroscopic observations of the Fe─K absorption structure in the luminous nearby quasar PG 1211+143, utilizing the X-ray Imaging and Spectroscopy Mission (XRISM). The primary objective is to characterize the Fe─K absorption features due to ultra-fast outflow (UFO) in this Eddington-luminosity source. Observations were conducted with XRISM's Resolve and Xtend instruments, complemented by simultaneous data from XMM-Newton and NuSTAR. A historically bright phase was captured. The Resolve spectra clearly reveal a prominent P Cygni profile and resolves the Fe─K absorption into six distinct velocity components, ranging from v = −0.074 to −0.405c. A similar superposition of multiple UFOs has been reported in PDS 456, suggesting that such a "UFO forest" structure may be a common feature of near Eddington-luminosity sources. Some UFO components exhibit narrow line widths of approximately σ ∼ 200 km s−1, which may indicate that the outflows have reached their terminal velocities, thereby resulting in a smaller velocity shear. The mass outflow rate is estimated to be  Ṁout∼1M⊙yr−1 , which is of the order of the Eddington accretion rate. This suggests a physically plausible scenario where the outflow is a significant channel for mass ejection.

Keywords: X-ray active galactic nuclei, High energy astrophysics
Formation of the Energetic Electrons at the Dipolarization Front and the Trailing Flux Pileup Region during Magnetic Reconnection. The dipolarization front (DF) and the flux pileup region (FPR) are crucial downstream structures in magnetic reconnection, where significant energetic electrons are frequently observed. Using a two-dimensional particle-in-cell simulation model, we investigate the formation of energetic electrons in both the DF and the trailing FPR. Our results demonstrate that the energetic electrons at pitch angles near 90° at both regions undergo a two-stage acceleration process: an initial nonadiabatic acceleration by the reconnection electric field at the reconnection site followed by downstream adiabatic acceleration. We find that the 90° pitch-angle energetic electrons in the FPR reach substantially higher energies than those at the DF, since they encounter a stronger reconnection electric field at the reconnection site in the first stage. Furthermore, two populations of energetic electrons with distinct energy ranges at pitch angles near 0° and 180° are identified at the DF. The lower-energy population exhibits energies close to the magnitude of the parallel potential at the DF, which dominates the formation of this population by accelerating the electrons towards the DF and providing the trapping mechanism. The higher-energy population is energized via the Fermi mechanism through multiple reflections within the contracting magnetic island downstream. These findings provide new insights into the generation of energetic electrons during magnetic reconnection.

Keywords: Space plasmas, Planetary magnetospheres, Plasma physics
The Chandra Strong Lens Sample: Measuring the Dynamical States and Relaxation Fraction of a Sample of 28 Strong Lensing Selected Galaxy Clusters. We present the results of our dynamical state proxy measurements performed on 28 strong lensing galaxy clusters from the Sloan Giant Arcs Survey. Using Chandra ACIS-I/S X-ray data supplemented with HST WFC3 imaging, we measure four morphological parameters: the concentration parameter (c), asymmetry parameter (A), centroid shift (log(w)), and the X-ray-BCG centroid separation (D [kpc]). Our goals are to (A) provide a robust classification of the dynamical state of the clusters in this strong lensing selected sample to enable studies that test various problems in cluster astrophysics and observational cosmology; (B) identify correlations, biases, or disagreements between different measurement proxies and cluster properties; and (C) measure the relaxation fraction (the fraction of clusters classified as relaxed based on X-ray morphology) and compare it to relaxation fractions from cluster samples selected using other methods. We combine the four morphological parameters into a single metric, the combined parameter M, which effectively separates the cluster sample into four dynamical state categories: relaxed, moderately relaxed, moderately disturbed, and disturbed. We find no significant trend in a cluster's dynamical state with its size, and only a weak, statistically limited dependence on mass and redshift. Based on our classification system, we find that  43%−9+9  of the clusters are relaxed, which is consistent with relaxation fractions measured for other cluster samples selected on mass-observables. This implies a strong lensing selected sample of clusters is on average dynamically similar to clusters selected via different methods.

Keywords: Galaxy clusters, Strong gravitational lensing, Intracluster medium, Observational astronomy
Search for Radio Pulsations from Neutron Star Candidates in Detached Binaries. Recent optical astrometric and spectroscopic surveys have identified numerous neutron star (NS) candidates in nonaccreting detached binary systems, but their compact-object nature remains unconfirmed. In this work, we present targeted radio observations of 31 such candidates using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), the Robert C. Byrd Green Bank Telescope, and the Shanghai TianMa Radio Telescope. Over a total of 46.65 hr of observing time, we detected neither periodic nor single-pulse radio emissions. These nondetections place stringent upper limits on the flux densities of any potential radio signals, reaching ∼4 μJy for periodic emission and ∼10 mJy for single pulses with FAST. Since our observations are highly sensitive and the flux density upper limits are well below the median fluxes of known Galactic pulsars, this suggests that geometric beaming is the most likely explanation for the nondetections if these objects are indeed pulsars. Alternatively, the NSs may be sufficiently old (≳10 Gyr) and have become intrinsically radio-quiet. In this case, our findings highlight the inherent difficulty of confirming NSs in such old detached binary systems through radio pulsation searches.

Keywords: Neutron stars, Detached binary stars, Radio pulsars
Variability of East─West Asymmetry in Energetic Storm Particle Intensities and Coronal Mass Ejection Deflection during Solar Cycles 23 and 24. We investigate the variability of the east─west asymmetry in energetic storm particle (ESP) heavy ion intensities at interplanetary shocks driven by coronal mass ejections (CMEs) during solar cycles (SCs) 23 and 24. We analyze helium (He), oxygen (O), and iron (Fe) intensities in the energy range of ∼0.13─3 MeV/nucleon, using observations from NASA's ACE and STEREO missions. We examine the longitudinal distribution of ESP intensities and their correlation with the near-Sun CME speed and average transit CME speed, distinguishing between eastern and western events. Our results reveal significant differences in the east─west asymmetry of ESP intensities between SC 23 and SC 24. This shift is linked to changes in the heliolongitude distribution of the CME Speed Ratio (the ratio of CME average transit speed to near-Sun speed), which transitions from peaking predominantly in the western heliosphere in SC 23 to the eastern heliosphere in SC 24. This shift suggests a systematic difference in CME deflection between the two cycles, with CMEs in SC 23 being, on average, deflected eastward, while those in SC 24 exhibit a tendency for westward deflection.

Keywords: Interplanetary shocks, Solar flares, Solar energetic particles, Space weather, Solar coronal mass ejection shocks
An Outflow from the X-Ray Corona as the Origin of Millimeter Emission from Radio-quiet AGNs. Recent observations of radio-quiet active galactic nuclei have shown the presence of millimeter emission, whose origin remains unknown, from within parsec scales of the central black hole. We argue that the millimeter emission comes from a spatially extended region that is magnetically connected to the compact X-ray corona, in analogy to the solar wind and corona. We present an analytic model scaled to corona values in which non-equipartition electrons from multiple heights along an extended conical outflow shape the millimeter emission. In this model, the 100 GHz emission originates from within ≲104 gravitational radii (rg) of the central black hole, though the projected distance from the black hole can be as low as 50rg depending on the line of sight. Our model predicts a flat emission spectrum  Fν∼const  and a millimeter-to-X-ray luminosity ratio Lmm/LX ∼ 10−4, consistent with observations. These quantities depend weakly on the underlying electron power-law distribution function and black hole mass. We demonstrate this model's plausibility using a general relativistic magnetohydrodynamic simulation of a thin accretion disc as a case study. Our model highlights the need to study continual dissipation along the outflow to connect the X-ray- and millimeter-emitting regions.

Keywords: Accretion, Supermassive black holes, High energy astrophysics, Radio quiet quasars, Non-thermal radiation sources, Radiative processes, Magnetic fields, Astrophysical black holes
Inferring Planet and Disk Parameters from Protoplanetary Disk Images Using a Variational Autoencoder. Dust-continuum observations of many protoplanetary disks (PPDs) reveal rings and gaps that are widely interpreted as evidence of ongoing planet formation. Here we present the first framework for inferring planet and disk parameters from such images using variational autoencoder (VAE)-based generative machine learning. The new framework is called Variational Autoencoder for Disks with Embedded Rings (VADER). We train VADER on synthetic images of dust-continuum emission, generated from FARGO3D hydrodynamic simulations postprocessed with Monte Carlo radiative-transfer calculations. VADER infers the masses of up to three embedded planets as well as the disk parameters α-viscosity, dust-to-gas ratio, Stokes number, and flaring index. VADER returns a full posterior distribution for each of these quantities. We demonstrate that VADER reconstructs disk morphologies with high structural similarity (index &gt; 0.99), accurately recovers planet parameters with R2 &gt; 0.9 across planet masses, and reliably predicts disk parameters. Applied to Atacama Large Millimeter/submillimeter Array (ALMA) dust-continuum images of 23 PPDs, our model returns mass estimates for embedded planets of 0.3─2 MJup that agree to within 1σ of published values in most cases, and infers disk parameters consistent with current literature. Once trained, the VAE performs full posterior parameter inference in a matter of minutes, offering statistical rigor with enough computational speed for application to large-scale ALMA surveys. These results establish VAE-based models as powerful tools for inferring from disk structure the masses of embedded planets and the global disk parameters, with their associated uncertainties.

Keywords: Planetary-disk interactions, Bayesian statistics, Protoplanetary disks
Quantitative Image-based Validation Framework for Assessing Global Coronal Magnetic Field Models. Coronagraph observations provide key information about the orientation of the Sun's magnetic field. Previous studies used various algorithms to segment quasi-radial features in coronagraph images and approximate their local plane-of-sky (POS) geometry and orientation, which can be used as input for optimizing and constraining coronal magnetic field models. We present a new framework that allows for further quantitative evaluations of image-based coronal segmentation methods against magnetic field models, and vice versa. We compare quasi-radial features identified from QRaFT, a global coronal feature tracing algorithm, in white-light coronagraph images to outputs of the Magnetohydrodynamic Algorithm outside a Sphere (MAS) model, an advanced MHD model. We use the FORWARD toolset to produce synthetic polarized brightness images coaligned to real coronagraph observations, segment features in these images, and quantify the difference between the inferred and model magnetic field. This approach allows us to geometrically compare features segmented in artificial images to those segmented in white-light coronagraph observations against the POS projected MAS coronal magnetic field. We quantify QRaFT's performance in the artificial images and observational data, and perform statistical analyses that measure the accuracy and uncertainty of the model output to the observational data. The results demonstrate that a coronal segmentation method identifies the global large-scale orientation of the coronal magnetic field within ∼±10∘ of the POS projected MAS magnetic field.

Keywords: Cross-validation , Model selection, Coronagraphic imaging, Solar corona, Solar magnetic fields, Solar coronal streamers
Search for γ-Ray Emission from Cluster of Galaxies with Fermi-LAT Data. In this work, we carry out a systematic search for γ-ray emission from 65 galaxy clusters based on 16 yr of Fermi Large Area Telescope data in the energy range from 500 MeV to 500 GeV. Only two clusters, A2065 and A2244, exhibit significant emission, with local significances of ∼5σ. The test statistic (TS) values are ∼25.4 for A2065 and ∼25.1 for A2244. We investigate a potential dark matter (DM) origin for these signals. The peak TS value of A2065 is ∼26.2 for the DM annihilation channel  χχ→bb̄  at a DM mass of mχ ∼ 25.0 GeV. For A2244, the largest TS value is ∼14.5 for  χχ→bb̄  at mχ ∼ 6.0 GeV. However, the corresponding cross sections conflict with the upper limits derived from observations of dwarf spheroidal galaxies. This indicates that these signals cannot be attributed to DM annihilation. Finally, we consider the γ-ray flux arising from hadronic cosmic-ray (CR) interactions in the intracluster medium, with the corresponding estimated volume-averaged CR-to-thermal pressure ratios being ∼4% and ∼16%, respectively.

Keywords: Galaxy clusters, Gamma-ray observatories, Cold dark matter
Data-constrained Magnetohydrodynamic Simulation of the Global Solar Corona Including Solar Wind Effects within 2.5 R<SUB>⊙</SUB>. Total solar eclipses (TSEs) provide a unique opportunity to observe the large-scale solar corona. The solar wind plays an important role in forming the large-scale coronal structure, and magnetohydrodynamic (MHD) simulations are used to reproduce it for further studying coronal mass ejections (CMEs). We conduct a data-constrained MHD simulation of the global solar corona including solar wind effects of the 2024 April 8 TSE with observed magnetograms using the message-passing interface adaptive mesh refinement versatile advection code (MPI-AMRVAC) within 2.5 R⊙. This TSE happened within the solar maximum, hence the global corona was highly structured. Our MHD simulation includes the energy equation with a reduced polytropic index γ = 1.05. We compare the global magnetic field for multiple magnetograms and use synchronic frames from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager to initialize the magnetic field configuration from a magnetofrictionally equilibrium solution, called the outflow field. We detail the initial and boundary conditions employed to time-advance the full set of ideal MHD equations such that the global corona is relaxed to a steady state. The magnetic field, the velocity field, and distributions of the density and thermal pressure are successfully reproduced. We demonstrate direct comparisons with TSE images in white light and Fe XIV emission augmented with quasi-separatrix layers, the integrated current density, and the synthetic white-light radiation, and find a good agreement between simulations and observations. This provides a fundamental background for future simulations to study the triggering and acceleration mechanisms of CMEs under solar wind effects.

Keywords: Solar atmosphere, Solar eclipses, Solar wind, Solar physics, Solar corona, Solar magnetic fields, Solar coronal streamers
The IRIS<SUP>2+</SUP> Inversion Tool: Recovering the Radiative Losses and the Thermodynamics in the Lower Solar Atmosphere. We introduce an improved and fast inversion tool that is able to provide the thermodynamics of the solar atmosphere from the photosphere to the top of the chromosphere, as well as the integrated radiative losses (IRLs) in the chromosphere for data observed by the Interface Region Imaging Spectrograph (IRIS). This NASA mission has been observing the Sun and providing, among other kinds of data, multiline spectral observations sensitive to changes in the lower solar atmosphere since 2013. In this paper, we explain the new inversion tool IRIS2+ based on the IRIS2+ database, which is based on 135,472 synthetic representative profiles (RPs), each of them consisting of six chromospheric lines and six photospheric lines, their corresponding representative model atmospheres (RMA), and the IRL associated with these atmospheres. A nearest neighbor (k-nn) model algorithm is trained with the synthetic representative profiles to predict the closest RP in the database to the one observed, at which point IRIS2+ assigns the RMA and the IRL to the location of that observed profile. We have compared the results obtained by IRIS2+ with results obtained from the state-of-the-art inversion code STiC, which is also used to build the IRIS2+ database. We find that the thermodynamics and the IRL obtained with both methods are comparable in most cases. Therefore, IRIS2+ is a fast and reliable inversion tool that provides approximate values of the thermodynamic state and the radiative losses in the lower solar atmosphere for a large variety of solar scenes observed with IRIS.

Keywords: Solar chromospheric heating, Solar chromosphere, Solar photosphere