Sazuna/UAT_keywords huggingface dataset:
A Large Catalog of DA White Dwarf Characteristics Using SDSS and Gaia Observations. We present a catalog of 8545 and 19,257 unique DA white dwarfs (WDs) observed in Sloan Digital Sky Survey (SDSS) Data Release 19 and previous SDSS data releases, respectively. This is the largest catalog of both spectroscopic and photometric measurements of DA WDs available to date, and we make this catalog and all codes used to create it publicly available. We measure the apparent radial velocity, spectroscopic effective temperature and surface gravity, and photometric effective temperature and radius for all objects in our catalog. We validate our measurements against other published WD catalogs. For apparent radial velocities, surface gravities, and effective temperatures measured from spectra with signal-to-noise ratios &gt; 50, our measurements agree with published SDSS WD catalogs to within 7.5 km s‑1, 0.060 dex, and 2.4%, respectively. For radii and effective temperatures measured with Gaia photometry, our measurements agree with other published Gaia data sets to within 0.0005 R⊙ and 3%, respectively. We use this catalog to investigate systematic discrepancies between WDs observed in SDSS-V and previous generations of SDSS. For objects observed in both SDSS-V and previous generations, we uncover systematic differences between measured spectroscopic parameters depending on which set of survey data is used. On average, the measured apparent radial velocity of a DA WD is 11.5 km s‑1 larger, and the surface gravity is 0.015 dex smaller when a WD's spectroscopic parameters are measured using SDSS-V data compared to using data from previous generations of SDSS. These differences may be due to changes in the wavelength solution across survey generations.

Keywords: Fundamental parameters of stars, White dwarf stars, DA stars
Cloud-to-cloud Velocity Dispersions Across a Local Arm Segment. Using a large sample of 9617 molecular clouds (MCs) from the Milky Way Imaging Scroll Painting survey, we mainly measure one-dimensional cloud-to-cloud velocity dispersions across a 450 deg2 segment of the Local Arm in the Galactic second quadrant. We define the cloud-to-cloud velocity dispersion using two metrics: the standard deviation (σbin) and flux-weighted rms value (σbin,w) of the centroid velocities of 12CO-detected MCs within spatial bins. The typical values of σbin and σbin,w are 7.5 ± 0.5 km s‑1 and 6.2 ± 0.5 km s‑1, respectively. After categorizing clouds by sizes into three types: Type S (0.15–1.2 pc), Type M (1.2–4.8 pc), and Type L (≳4.8 pc), we find that the spatial distribution of Type S and M MCs projected onto the Galactic longitude–latitude (l–b) plane is generally uniform. Additionally, the cloud-to-cloud velocity dispersion among Type S clouds (∼7.6 and 7.4 km s‑1 for σbin and σbin,w, respectively) is systematically greater than that among Type M clouds (∼6.7 and 6.0 km s‑1 for σbin and σbin,w, respectively), with differences of 0.9–1.4 km s‑1. From these measurements, we estimate merger timescales between MCs to be approximately 0.3–0.9 Myr, which is shorter than their internal crossing timescales (∼1 Myr for Type S, ∼2 Myr for Type M, and ≳5 Myr for Type L). This disparity, particularly pronounced for larger Type L clouds, suggests that MCs are dynamically transient structures, with their gas content changing due to frequent interactions with neighboring clouds.

Keywords: Interstellar clouds, Molecular clouds, Interstellar medium
Characterizing the Observational Properties of the Sun's High-latitude m = 1 Inertial Mode. Low-m inertial modes have been recently discovered in the Sun's high-latitude regions. In this study, we characterize the observational properties of the m = 1 mode by analyzing time–distance subsurface flow maps. Synoptic flow maps, constructed from daily subsurface flow maps using a tracking rate corresponding to the rotation at latitude 65°, are filtered in both the spherical harmonic and Fourier domains to retain only the m = 1 mode and its dominant frequencies. Our analysis reveals a power distribution that is significantly stronger in the northern polar region. The mode's power exhibits an anticorrelation with solar activity, remaining strong and persistent during the solar activity minimum and becoming weaker and more fragmented during the solar maximum. Magnetic flux transported from low to high latitudes influences both the mode's power and lifetime, enhancing its power and shortening its lifetime upon arrival. The phases of the m = 1 mode in the northern and southern polar regions are near-antisymmetric for most of the time with short deviations. We also compute zonal and meridional phase velocities of the mode and find that it exhibits significantly less differential rotation than its surrounding plasma. The meridional phase velocity, comprising both the local plasma's meridional flow and the mode's intrinsic phase motion, is directed poleward below latitude 70° and equatorward above this latitude. These observational findings underscore the need for a deeper understanding of the internal dynamics of the low-m modes, which may offer valuable insights into the structure and dynamics of the solar interior.

Keywords: Solar oscillations, Solar rotation, Helioseismology, Solar interior
Time-dependent Radiation Transport Simulations of Infrared Echoes from Dust-shrouded Luminous Transients. A range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOTs), can occur in dusty environments initially opaque to transients' optical/UV light, becoming visible only once the dust is destroyed by transients' rising luminosity. We present axisymmetric, time-dependent radiation transport simulations of dust-shrouded transients with Athena++ and tabulated gray opacities, predicting the light curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light curve depend on whether the transient rises rapidly or slowly compared to the light-crossing time of the photosphere, tlc. For slow-rising transients (trise ≫ tlc) like SNe, the reprocessed IR radiation diffuses outward through the dust shell faster than the shell sublimates; the IR light curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale ∼trise shorter than the transient duration. By contrast, for fast-rising transients (trise ≪ tlc) such as FBOTs and some TDEs, the finite light-travel time results in the reprocessed radiation arriving as an "echo" lasting much longer than the transient itself. We explore the effects of the system geometry by considering a torus-shaped distribution of dust. The IR light curves seen by observers in the equatorial plane of the torus resemble those for a spherical dust shell, while polar observers see faster-rising, brighter, and shorter-lived emission. We successfully model the IR excess seen in AT2018cow as a dust echo, supporting the presence of an opaque dusty medium surrounding FBOTs prior to explosion.

Keywords: High energy astrophysics, Transient sources, Infrared sources
Reassessing Sub-Neptune Structure, Radii, and Thermal Evolution. We present a novel python-based 1D sub-Neptune evolution model that emphasizes the thermal evolution and potential solidification of the rock/iron core and the structure of the radiative atmosphere. This model explores planetary structure from the molten center to nbar pressure levels. Treating the radiative atmosphere is crucial for sub-Neptunes, due to the large scale height and low gravity, which contributes up to 40% of their observed radius, especially for low-mass, highly irradiated planets. Consequently, we generically find that lower H/He mass fractions are needed to match a given planetary radius, compared to previous work. While the presence of metal enrichment in the H/He layers (here modeled as 50× solar) does not substantially influence the size of the convective envelope, it notably reduces the transit radius by shrinking the radiative atmospheric scale height. Sub-Neptunes cool differently from terrestrial planets, with the rock/iron core's cooling rate limited by the envelope, leading to longer solidification timescales. Complete solidification of the silicate mantle by 10 Gyr is found only for planets with very low masses (≤1M⊕) and small H/He envelopes (≤0.1%). Dynamo action in sub-Neptune iron cores persists as long as the mantle surface remains molten, often exceeding 10 Gyr, and becomes sensitive to core thermal conductivity after solidification. We examine aspects of "boil-off," which sets the maximum allowed H/He mass and planetary radius for subsequent evolution. The rock/iron's cooling energy moderately decreases the post-boil-off H/He mass fraction in planets with large atmospheric scale heights only.

Keywords: Exoplanet structure, Exoplanet evolution, Planetary atmospheres, Planetary interior
Peering into the Heart of Darkness with VLBA: Radio-quiet Active Galactic Nucleus in the JWST North Ecliptic Pole Time-domain Field. We present initial results from the 4.8 GHz Very Long Baseline Array (VLBA) survey of the JWST North Ecliptic Pole Time-Domain Field (TDF). From 106 radio sources found in the Karl G. Jansky Very Large Array (VLA) observations in the TDF, we detected 12 sources (∼11% detection rate) at ∼3.3 μJy rms sensitivity and ∼4 mas resolution. Most detections exhibit parsec-scale emission (less than 40 pc) with high VLBA/VLA flux density ratios and brightness temperatures exceeding 105 K, confirming nonthermal active galactic nucleus (AGN) activity. Spectral indices α ≳ ‑0.5 correlate with higher VLBA/VLA flux ratios, consistent with synchrotron emission from AGN coronae or jets. In the majority of our sources, star formation contributes less than 50% of the total VLBA radio emission, with a few cases where the emission is almost entirely AGN driven. Although the radio emission from radio quiet AGN is thought to be primarily driven by star formation, our VLBA observations confirm that there is also often a contribution at various levels from black hole driven AGN. Eight VLBA detections have JWST/NIRCam counterparts, predominantly early-type, bulge-dominated galaxies, which we use to get an estimate of the redshift and star formation rate (SFR). Wide-field Infrared Survey Explorer colors indicate that VLBA detections are either AGN or intermediate-disk-dominated systems, while VLBA nondetections correspond to extended, star-forming galaxies. We compare SFRs derived from previous SCUBA-2 850 μm observations with new JWST-based estimates, and discuss the observed discrepancies, highlighting JWST's improved capability to disentangle AGN activity from star formation.

Keywords: High energy astrophysics, Active galaxies, Radio galaxies, Active galactic nuclei, Radio sources
SO Emission in the Dynamically Perturbed Protoplanetary Disks around CQ Tau and MWC 758. We report the serendipitous detection of the SO JN = 65─54 (219.949 GHz) rotational transition in archival Atacama Large Millimeter/submillimeter Array observations of the spiral hosting protoplanetary disks around CQ Tau (with ≍4.9σ significance) and MWC 758 (with ≍3.4σ significance). In the former, the SO emission comes in the shape of a ring, arises from the edge of the continuum cavity, and is qualitatively consistent, at the currently available spectral resolution, with being in Keplerian rotation. In the latter, instead, while arising primarily from inside the continuum cavity, the SO emission also extends to the continuum ring(s), and its morphology and kinematics are less clear. We put these sources in the context of the other protoplanetary disks where SO detections have been previously reported in the literature and discuss the possible origins of SO in terms of (thermal) desorption or formation in the gas-phase. We argue that these processes might be fostered by dynamical perturbations caused by unseen embedded massive companions, shadows, or late-time infall, thus suggesting a possible link between perturbed dynamics and SO emission in (these) protoplanetary disks. If confirmed, our interpretation would imply that chemical evolution timescales could be significantly shorter in these systems than is commonly assumed, indicating that dynamical perturbations might influence the composition of newborn (proto)planets by altering the volatile makeup of their formation environment.

Keywords: Submillimeter astronomy, Protoplanetary disks, Planet formation, Astrochemistry
Spectroscopic Ultraluminous Lyα Luminosity Functions at z = 5.7 and z = 6.6 from HEROES: Evidence for Ionized Bubbles. We present spectroscopic Lyα luminosity functions (LFs) at z = 5.7 and z = 6.6 based on a large 209 source sample of Lyα emitter (LAE) candidates identified in Subaru/Hyper Suprime-Cam narrowband imaging and confirmed with Keck II/DEIMOS spectroscopy over a multiyear observing campaign. After applying photometric and spectroscopic cuts to produce homogeneous samples, we use the resulting samples of 49 z = 5.7 and 56 z = 6.6 LAEs to compute spectroscopic LAE LFs at each redshift. We correct our LFs for incompleteness using a source-injection simulation. We find excellent agreement with current spectroscopic and photometric LAE LFs from the literature. We look for evolution over the redshift range z = 5.7─6.6. We find a strong convergence of the LFs at LLyα ≳ 1043.4 erg s−1. This convergence (noted in previous literature) provides strong evidence that the most luminous LAEs at z = 6.6 form ionized bubbles around themselves, allowing for greater Lyα transmission through the neutral intergalactic medium, which is measured as an increase in the bright end of the z = 6.6 LF over the expected evolution in the LF based on the faint end. We infer that ultraluminous LAEs may play a significant role in reionization.

Keywords: Lyman-alpha galaxies, Reionization, Narrow band photometry
Formation Pathways of Compact Elliptical Galaxies: Perspective of Internal Structures. We present a structural analysis of 138 compact elliptical galaxies (cEs) in the redshift range of z &lt; 0.05 using the Sloan Digital Sky Survey (SDSS) DR12 data. We perform single- and double-component Sérsic model fitting to their SDSS r-band surface brightness profiles. By dividing cEs into those with [cE(w)] and without [cE(w/o)] a bright host galaxy, we find a significant structural dichotomy: the majority (∼85%) of cE(w)s exhibit single-component profiles, while a similar proportion (∼85%) of isolated cE(w/o)s display double-component profiles, characterized by a compact, inner component and a diffuse, disk-like outer component. These results suggest that host-associated cE(w)s primarily form through the tidal stripping of larger progenitors, resulting in a compact bulge-like core. In contrast, isolated cE(w/o)s appear to form intrinsically at early epochs, likely through gas-rich mergers, and retain disk-like outer structures. The Sérsic index distribution of cE(w)s with single-component structure indicates progenitor types ranging from pseudobulge to classical bulge, supported by differences in stellar populations. A small fraction of cEs, including double-component cE(w)s and single-component cE(w/o)s, suggests complex evolutionary channels involving environmental capture or ejection. Our results emphasize that the structural characteristics of cEs, specifically the presence or absence of an extended outer envelope, serve as a crucial diagnostic tool to distinguish tidally stripped remnants from intrinsically formed low-mass cEs in isolation.

Keywords: Galaxy formation, Compact galaxies, Stellar populations, Galaxy structure, Compact dwarf galaxies, Galaxy evolution, Compact objects, Tidal interaction, Elliptical galaxies
Analysis of Two Models for the Angular Structure of the Outflows Producing the Swift/XRT "Larger-angle Emission" of Gamma-Ray Bursts. The quasi-instantaneous emission from a relativistic surface endowed with a Lorentz factor that decreases away from the outflow symmetry axis can naturally explain the three phases observed by Swift X-Ray Telescope (XRT) in gamma-ray bursts (GRBs) and their afterglows (GRB tail, afterglow plateau, and postplateau) based only on the angular change of the relativistic Doppler boost across the outflow surface. We develop further the analytical formalism of the "larger-angle emission" model for the case of "n-exponential" outflows (where the Lorentz factor Γ dependence of the angular location θ is  Γ∼exp{‑(θ/θc)n} ), and compare its ability to account for the X-ray emission of XRT afterglows relative to that of "power-law" outflows (Γ ∼ θ‑g). Power-law outflows yield longer afterglow plateaus, followed by slower postplateau flux decays than n-exponential outflows, features which may be used in identifying which type of angular structure is at work in a given afterglow. Identifying the Γ(θ) angular structure that accommodates XRT light curves is slightly complicated by the fact that the afterglow X-ray light curve is also determined by how two characteristics of the comoving-frame emission spectrum (peak energy  Ep'  and peak intensity  ip' ) change with the angular location or, equivalently, with the Lorentz factor. Here, we assume power-law Γ dependences of those spectral characteristics and find that, unlike power-law outflows, n-exponential outflows cannot account for plateaus with a temporal dynamical range larger than 100 (2 dex in logarithmic space). To capture all the information contained in XRT afterglow measurements (0.3–10 keV unabsorbed flux and effective spectral slope), we calculate 0.3 and 10 keV light curves using a broken-power-law emission spectrum of peak energy and low- and high-energy slopes that are derived from the effective slope measured by XRT. This economical peak energy determination is found to be consistent with the results of more expensive spectral fits. The angular distributions of the Lorentz factor, comoving frame peak energy, and peak intensity ( Γ(θ),Ep'(θ),ip'(θ) ) constrain the (yet-to-be determined) convolution of various features of the production of relativistic jets by solar-mass black holes and of their propagation through the progenitor/circumburst medium, while the  Ep'(Γ)  and  ip'(Γ)  dependences may constrain the GRB dissipation mechanism and the GRB emission process.

Keywords: Gamma-ray bursts, Non-thermal radiation sources
Biosignature False Positives in Potentially Habitable Planets around M Dwarfs: The Effect of UV Radiation from One Flare. Many past studies have predicted the steady-state production and maintenance of abiotic O2 and O3 in the atmospheres of CO2-rich terrestrial planets orbiting M dwarf stars. However, the time-dependent responses of these planetary atmospheres to flare events—and the possible temporary production or enhancement of false-positive biosignatures therein—has been comparatively less well studied. Most past works that have modeled the photochemical response to flares have assumed abundant free oxygen, like that of the modern or Proterozoic Earth. Here we examine in detail the photochemical impact of the UV emitted by a single flare on abiotic O2/O3 production in prebiotic, CO2-dominated atmospheres of M dwarf planets with CO2 levels ranging from 3% to 80% of 1 bar. We find that a single flare generally destroys O2 and O3 over short timescales while modestly enhancing their column densities over intermediate timescales. We simulate the spectral observables of both the steady-state atmosphere and time-dependent spectral response over the flare window for both emitted and transmitted light spectra. Over the course of the flare, the O3 UV Hartley band is decreased by a maximum of 47 ppm. In both emitted and transmitted light spectra, the 9.65 μm O3 band is hidden by the overlapping 9.4 μm CO2 band for all scenarios considered. Overall, we find that the possible enhancements of abiotic O3 due to a single flare are small compared to O3's sensitivity to other parameters such as CO2 and H2O abundances or the availability of reducing gases such as H2.

Keywords: M dwarf stars, Exoplanets, Stellar flares, Biosignatures, Habitable planets, Exoplanet atmospheres
Self-consistent Dynamical and Chaotic Tides in the REBOUNDx Framework. At high eccentricities, tidal forcing excites vibrational modes within orbiting bodies known as dynamical tides. In this paper, we implement the coupled evolution of these modes with the body's orbit in the REBOUNDx framework, an extension to the popular N-body integrator REBOUND. We provide a variety of test cases relevant to exoplanet dynamics and demonstrate overall agreement with prior studies of dynamical tides in the secular regime. Our implementation is readily applied to various high-eccentricity scenarios and allows for fast and accurate N-body investigations of astrophysical systems for which dynamical tides are relevant.

Keywords: Exoplanet dynamics, Tides, Open source software
Radio Morphology of Gamma-Ray Sources. II. Giant Radio Galaxies. Giant radio sources, including galaxies and quasars (hereafter GRSs), are active galactic nuclei (AGN) hosting relativistic jets with source sizes exceeding a projected length of 0.7 Mpc. They are crucial to understanding the evolution of radio sources and their interaction with the surrounding environment. Some of these enigmatic objects, e.g., NGC 315, have also been reported as γ-ray emitters. Since GRSs are thought to be aligned close to the plane of the sky, they are invaluable targets to explore the radiative mechanisms responsible for the observed γ-ray emission. We have carried out a systematic search of γ-ray-emitting GRSs using sensitive low-resolution radio surveys, such as by the Low Frequency Array, NRAO Very Large Array Sky Survey, and Rapid ASKAP Continuum Survey, and considering the fourth data release of the fourth Fermi Large Area Telescope γ-ray source (4FGL-DR4) catalog. By carefully inspecting the radio maps of all AGN included in the 4FGL-DR4 catalog, we have identified 16 γ-ray-emitting GRSs, including eight that are being reported as GRSs for the first time. Some of their observed parameters, e.g., core dominance, appeared to differ from those found for the non-γ-ray detected GRS population, possibly due to the relatively small viewing angle of the γ-ray-emitting jet. The observed γ-ray properties of these objects were found to be similar to those of non-GRS γ-ray-emitting misaligned AGN. We conclude that the origin of the γ-ray emission could be similar in both source populations.

Keywords: Gamma-ray astronomy, Giant radio galaxies
MeV Cosmic-Ray Electrons Modify the TeV Pair-beam Plasma Instability. Relativistic pair beams created in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to produce a detectable GeV-scale electromagnetic cascade, but the cascade component is absent in the spectra of many hard-spectrum TeV-emitting blazars. One common explanation is that weak intergalactic magnetic fields deflect the electron–positron pairs away from our line of sight. An alternative possibility is that electrostatic beam-plasma instabilities drain the energy of these pairs before a cascade can develop. Recent studies have shown that beam scattering by oblique electrostatic modes leads to minimal energy loss. But these modes might be suppressed by linear Landau damping (LLD) due to MeV-scale cosmic-ray electrons in the IGM. In this work, we explore the impact of LLD on the energy-loss efficiency of plasma instabilities in pair beams associated with 1ES 0229+200. We find that LLD effectively suppresses oblique electrostatic modes, while quasi-parallel ones grow to larger amplitudes. In this way, LLD enhances the energy-loss efficiency of the instability by more than an order of magnitude.

Keywords: Blazars, Gamma-rays, Intergalactic medium