Sazuna/UAT_keywords huggingface dataset:
Connecting Lyα and Ionizing Photon Escape in the Sunburst Arc. We investigate the Lyα and Lyman continuum (LyC) properties of the Sunburst Arc, a z = 2.37 gravitationally lensed galaxy with a multiply imaged, compact region leaking LyC and a triple-peaked Lyα profile indicating direct Lyα escape. Non-LyC-leaking regions show a redshifted Lyα peak, a redshifted and central Lyα peak, or a triple-peaked Lyα profile. We measure the properties of the Lyα profile from different regions of the galaxy using R ∼ 5000 Magellan/Magellan Echellette spectra. We compare the Lyα spectral properties to LyC and narrowband Lyα maps from Hubble Space Telescope imaging to explore the subgalactic Lyα‑LyC connection. We find strong correlations (Pearson correlation coefficient r &gt; 0.6) between the LyC escape fraction ( ) and Lyα (1) peak separation v sep, (2) ratio of the minimum flux density between the redshifted and blueshifted Lyα peaks to continuum flux density  , and (3) equivalent width. We favor a complex H I geometry to explain the Lyα profiles from non-LyC-leaking regions and suggest two H I geometries that could diffuse and/or rescatter the central Lyα peak from the LyC-leaking region into our sight line across transverse distances of several hundred parsecs. Our results emphasize the complexity of Lyα radiative transfer and its sensitivity to the anisotropies of H I gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct-escape Lyα, blueshifted Lyα, and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Lyα and LyC escape.

Keywords: Lyman-alpha galaxies, Starburst galaxies, Strong gravitational lensing, Radiative transfer
Generation of Fast Magnetoacoustic Waves in the Corona by Impulsive Bursty Reconnection. Fast-mode magnetohydrodynamic waves in the solar corona are often known to be produced by solar flares and eruptive prominences. Here, we simulate the effect of the interaction of an external perturbation on a magnetic null in the solar corona, which results in the formation of a current sheet (CS). Once the CS undergoes a sufficient extension in its length and squeezing of its width, it may become unstable to the formation of multiple impulsive plasmoids. Eventually, the plasmoids merge with one another to form larger plasmoids and/or are expelled from the sheet. The formation, motion, and coalescence of plasmoids with each other and with magnetic Y-points at the outer periphery of the extended CS are found to generate wavelike perturbations. An analysis of the resultant quasiperiodic variations of pressure, density, velocity, and magnetic field at certain locations in the model corona indicates that these waves are predominantly fast-mode magnetoacoustic waves. For typical coronal parameters, the resultant propagating waves carry an energy flux of 105 erg cm‑2 s‑1 to a large distance of at least 60 Mm away from the CS. In general, we suggest that both waves and reconnection play a role in heating the solar atmosphere and driving the solar wind and may interact with one another in a manner that we refer to as a "symbiosis of waves and reconnection."

Keywords: Active solar corona
A Spectroscopic and Interferometric Study of W Serpentis Stars. I. Circumbinary Outflow in the Interacting Binary W Serpentis. W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W Ser remain a mystery. Here, we present an observational analysis of high-quality, visible-band spectroscopy made with the Apache Point Observatory 3.5 m telescope and Astrophysical Research Consortium Echelle Spectrograph spectrograph plus the first near-IR, long-baseline interferometric observations obtained with the Center for High Angular Resolution Astronomy Array. We present examples of the appearance and radial velocities of the main spectral components: prominent emission lines, strong shell absorption lines, and weak absorption lines. We show that some of the weak absorption features are associated with the cool mass donor, and we present the first radial velocity curve for the donor star. The donor's absorption lines are rotationally broadened, and we derive a ratio of donor to gainer mass of 0.36 ± 0.09 based on the assumptions that the donor fills its Roche lobe and that it rotates synchronously with the orbit. We use a fit of the All-Sky Automated Survey light curve to determine the orbital inclination and mass estimates of 2.0M ⊙ and 5.7M ⊙ for the donor and gainer, respectively. The partially resolved interferometric measurements of orbital motion are consistent with our derived orbital properties and the distance from Gaia EDR3. Spectroscopic evidence indicates that the gainer is enshrouded in an opaque disk that channels the mass transfer stream into an outflow through the L3 region and into a circumbinary disk.

Keywords: High resolution spectroscopy, Long baseline interferometry, Interacting binary stars, Stellar mass loss
Detection of the Temperature Dependence of the White Dwarf Mass–Radius Relation with Gravitational Redshifts. Models predict that the well-studied mass–radius relation of white dwarf stars depends on the temperature of the star, with hotter white dwarfs having larger masses at a given radius than cooler stars. In this paper, we use a catalog of 26,041 DA white dwarfs observed in Sloan Digital Sky Survey Data Releases 1–19. We measure the radial velocity, effective temperature, surface gravity, and radius for each object. By binning this catalog in radius or surface gravity, we average out the random motion component of the radial velocities for nearby white dwarfs to isolate the gravitational redshifts for these objects and use them to directly measure the mass–radius relation. For gravitational redshifts measured from binning in either radius or surface gravity, we find strong evidence for a temperature-dependent mass–radius relation, with warmer white dwarfs consistently having greater gravitational redshifts than cool objects at a fixed radius or surface gravity. For warm white dwarfs, we find that their mean radius is larger and mean surface gravity is smaller than those of cool white dwarfs at 5.2σ and 6.0σ significance, respectively. Selecting white dwarfs with similar radii or surface gravities, the significance of the difference in mean gravitational redshifts between the warm and cool samples is &gt;6.1σ and &gt;3.6σ for measurements binned in radius and surface gravity, respectively, in the direction predicted by theory. This is an improvement over previous implicit detections, and our technique can be expanded to precisely test the white dwarf mass–radius relation with future surveys.

Keywords: Fundamental parameters of stars, White dwarf stars, General relativity, DA stars
SAUNAS. II. Discovery of Cross-shaped X-Ray Emission and a Rotating Circumnuclear Disk in the Supermassive S0 Galaxy NGC 5084. Combining Chandra, Atacama Large Millimeter/submillimeter Array, EVLA, and Hubble Space Telescope archival data and newly acquired data from the Apache Point Observatory/Dual Imaging Spectrograph, we detect a double-lobed 17 kpc X-ray emission with plumes oriented approximately perpendicular and parallel to the galactic plane of the massive lenticular galaxy NGC 5084 at 0.3─2.0 keV. We detect a highly inclined ( ), molecular circumnuclear disk (  pc) in the core of the galaxy rotating (V   km s−1) in a direction perpendicular to that of the galactic disk, implying a total mass of   for NGC 5084's supermassive black hole. Archival EVLA radio observations at 6 and 20 cm reveal two symmetric radio lobes aligned with the galactic plane, extending to a distance of   from the core, oriented with the polar axis of the circumnuclear disk. The spectral energy distribution lacks strong emission lines in the optical range. Three formation scenarios are considered to explain these multiwavelength archival observations: (1) active galactic nuclei (AGN) reorientation caused by accretion of surrounding material, (2) AGN-driven hot gas outflow directed along the galactic minor axis, or (3) a starburst/supernovae driven outflow at the core of the galaxy. This discovery is enabled by new imaging analysis tools including the Selective Amplification of Ultra Noisy Astronomical Signal, demonstrating the abundance of information still to be exploited in the vast and growing astronomical archives.

Keywords: AGN host galaxies, Supermassive black holes, Extragalactic radio sources, Hubble Space Telescope, X-ray telescopes, X-ray active galactic nuclei, Galaxy circumnuclear disk, Radio active galactic nuclei
Are Long Gamma-Ray Bursts Progenitors to Merging Binary Black Holes?. The distribution of delay times between the formation of binary black hole (BBH) progenitors and their gravitational-wave (GW) merger provides important clues about their unknown formation histories. When inferring the delay time distribution, it is typically assumed that BBH progenitor formation traces the star formation rate (SFR). In this work, we consider the rate of long gamma-ray bursts (LGRBs) instead of the SFR. LGRBs are thought to correspond to the formation of (possibly spinning) black holes, and may therefore be related to the BBH progenitor population. By comparing the redshift evolution of the LGRB rate as inferred by G. Ghirlanda &amp; R. Salvaterra and the BBH merger rate inferred by LIGO-Virgo-KAGRA observations, we find that the delay time distribution between LGRBs and BBH mergers is well described by a power law with minimum delay time 10 Myr and slope   (90% credibility). This matches theoretical expectations for the BBH delay time distribution, which in turn lends support to the hypothesis that LGRBs trace BBH progenitor formation. However, comparing the absolute rates of these two populations, we find that at most   of LGRBs may evolve into merging BBHs. We also consider the possibility that LGRBs only produce BBH systems with large aligned spins (with effective inspiral spin χeff &gt; 0.2). In this case, we find   and the delay time distribution favors the steepest power-law slopes we consider (α = ‑2). We argue that asynchronous observations of LGRBs and GWs provide a powerful multimessenger probe of black hole life cycles across cosmic history.

Keywords: Gamma-ray bursts, Massive stars, Stellar mass black holes, Gravitational wave astronomy, Astrophysical black holes
Turbulent Transport Characteristics of the Particles within Pulsar Wind Nebulae 3C58 and G54.1+0.3. Turbulent transport characteristics of the particles within two Crab-like pulsar wind nebulae (PWNe), 3C58 and G54.1+0.3, are investigated in the framework of a time-dependent turbulent diffusion model. The model takes the gyroresonant interactions between the particles and turbulent waves into account, which enables us to self-consistently determine the energy and spatial coefficients of particles within the nebula via the distributions of turbulent waves. Our application of the model to the multiband emission from 3C58 and G54.1+0.3 reveals the following. (1) The energy and spatial diffusion coefficients seem to follow quasi-linear distributions in the Kolmogorov-type turbulence, but consistent with nonlinear distributions at low energies in the Kraichnan-type turbulence due to the effects of the turbulent scattering. (2) The stochastic acceleration and spatial diffusion processes may play a role in modifying the electron spectrum in the Kolmogorov-type turbulence, whereas in the Kraichnan-type turbulence the energy exchange between the turbulent waves and particles is more efficient, resulting in more significant effects of the stochastic acceleration and spatial diffusion processes on the electron spectrum at the low energies of E e ≲ 1 TeV. (3) At the high energies of E e ≳ 1 TeV, the diffusion transport appears to be less effective for the evolution of the particles within 3C58 and G54.1+0.3 because the synchrotron radiative cooling process dominates over the particle transport. These two Crab-like PWNe are expected to be electron PeVatrons in the Galaxy, with a common slow diffusion escape occurring in both 3C58 and G54.1+0.3.

Keywords: Supernova remnants, Pulsar wind nebulae, Pulsars
Hilbert Transform Reveals Unusual Modulation in Delta Scuti Star KIC 10407873. We report a δ Scuti star, KIC 10407873, exhibiting significant amplitude modulation. Fourier analysis of Kepler long-cadence data (i.e., Q0-Q17, spanning 1471 days) reveals two distinct features: harmonic series of frequencies in the low-frequency region and the frequencies of the split triplet lines in the high-frequency region. Using the Hilbert transform method, we separated the amplitude modulation signals, obtaining precise parameters for the two modulation frequencies. For the harmonic series of frequencies in the low-frequency region, we isolated them through a prewhitening process. Based on the residual segmented spectrum and the phase-folding diagram, we propose that these harmonic series of frequencies may be caused by temperature inhomogeneity on the stellar surface and stellar rotation. The subsequent phase evolution diagrams we generated, combined with LAMOST's   data, further support this hypothesis. Consequently, this suggests that the cause of amplitude modulation in the high-frequency region is unrelated to stellar rotation. Finally, we discussed the information potentially carried by the isolated modulation signals, as well as the similarities between the star's dual-amplitude modulation and the periodically modulated Tseraskaya–Blazhko effect.

Keywords: Asteroseismology, Delta Scuti variable stars, Blazhko effect
Leptohadronic Scenarios for TeV Extensions of Gamma-Ray Burst Afterglow Spectra. Recent multiwavelength observations of gamma-ray burst afterglows observed in the TeV energy range challenge the simplest synchrotron self-Compton (SSC) interpretation of this emission and are consistent with a single power-law component spanning over 8 orders of magnitude in energy. To interpret this generic behavior in the single-zone approximation without adding further free parameters, we perform an exhaustive parameter space study using the public, time-dependent, multimessenger transport software AM  3 . This description accounts for the radiation from nonthermal protons and the leptohadronic cascade induced by pp and p γ interactions. We summarise the main scenarios that we have found (SSC, Extended-syn, Proton-syn, pp-cascade, and pγ-cascade) and discuss their advantages and limitations. We find that possible high-density environments, as may be typical for surrounding molecular cloud material, offer an alternative explanation for producing flat hard (source) spectra up to and beyond energies of 10 TeV.

Keywords: X-ray astronomy, Gamma-ray bursts, Theoretical models, Shocks, Radiative transfer simulations, Relativistic jets, Astronomical radiation sources, Non-thermal radiation sources, Gamma-ray astronomy, Particle astrophysics, Cosmic rays
A Series of (Net) Spin-down Glitches in PSR J1522–5735: Insights from the Vortex Creep and Vortex Bending Models. Through a detailed timing analysis of Fermi-LAT data, the rotational behavior of the γ-ray pulsar PSR J1522‑5735 was tracked from 2008 August (MJD 54692) to 2024 January (MJD 60320). During this 15.4 yr period, two overrecovery glitches and four antiglitches were identified, marking a rare occurrence in rotation-powered pulsars (RPPs). The magnitudes of these (net) spin-down glitches were determined to be ∣Δν g/ν∣ ∼ 10‑8, well above the estimated detectability limit. For the two overrecovery glitches, the respective recovery fractions Q are 2.1(7) and 1.4(2). Further analysis showed no substantial variations in either the flux or pulse profile shape in any of these events, suggesting that small (net) spin-down glitches, unlike large events observed in magnetars and magnetar-like RPPs, may occur without leaving an impact on the magnetosphere. Within the framework of the vortex creep and vortex bending models, antiglitches and overrecoveries indicate the recoupling of vortex lines that moved inward as a result of a crustquake; meanwhile, the apparent fluctuations in the spin-down rate after the glitches occur as a result of the coupling of the oscillations of bent vortex lines to the magnetosphere.

Keywords: Gamma-ray astronomy, Rotation powered pulsars, Time series analysis
Fast Methods for Computing Photometric Variability of Eccentric Binaries: Boosting, Lensing, and Variable Accretion. We analyze accretion-rate time series for equal-mass binaries in coplanar gaseous disks spanning a continuous range of orbital eccentricities up to 0.8 for both prograde and retrograde systems. The dominant variability timescales match those of previous investigations; the binary orbital period is dominant for prograde binaries with e ≳ 0.1, with a 5 × longer "lump" period taking over for e ≲ 0.1. This lump period fades and drops from 5 × to 4.5 × the binary period as e approaches 0.1, where it vanishes. For retrograde orbits, the binary orbital period dominates at e ≲ 0.55 and is accompanied by a 2 × longer timescale periodicity at higher eccentricities. The shape of the accretion-rate time series varies with binary eccentricity. For prograde systems, the orientation of an eccentric disk causes periodic trading of accretion between the binary components in a ratio that we report as a function of binary eccentricity. We present a publicly available tool, binlite, that can rapidly (≲0.01 s) generate templates for the accretion-rate time series onto either binary component for choice of binary eccentricity below 0.8. As an example use case, we build lightcurve models where the accretion rate through the circumbinary disk and onto each binary component sets contributions to the emitted specific flux. We combine these rest-frame, accretion-variability lightcurves with observer-dependent Doppler boosting and binary self-lensing. This allows a flexible approach to generating lightcurves over a wide range of binary and observer parameter space. We envision binlite as the access point to a living database that will be updated with state-of-the-art hydrodynamical calculations as they advance.

Keywords: Accretion, Hydrodynamical simulations, Binary stars, Gravitational waves, Time domain astronomy
A Massive White Dwarf or Low-mass Neutron Star Discovered by LAMOST. We report the discovery of a close binary J0606+2132 (Gaia DR3 3423365496448406272) with P obs = 2.77 days containing a possible massive white dwarf (WD) or a neutron star (NS) using LAMOST spectroscopic data. By a joint fitting of the radial velocity from LAMOST and the light curve from TESS, we derived a circular Keplerian orbit with an inclination of i = 81.°31 , which is consistent with that derived from  . Together with the mass of the visible star, we derived the mass of the invisible object to be  . Spectral disentangling with the LAMOST medium-resolution spectra shows no absorption feature from an additional component, suggesting the presence of a compact object. No X-ray or radio pulsed signal is detected from ROSAT and FAST archive observations. J0606+2132 could evolve into either a Type Ia supernova or an NS through accretion-induced collapse if it is a WD or into an intermediate-mass X-ray binary if it is an NS.

Keywords: Neutron stars, White dwarf stars, Binary stars
The Effects of Turbulent Electrical Resistivity on the Response of the Solar Atmosphere to Flare Energy Input. I. Results of Radiative Hydrodynamic Simulations. A number of works have considered the role of turbulence in energy release and transport in solar flares, and in particular, on the transport of energy by thermal conduction. Here, we point out that for physical consistency, the effects of turbulence on the electrical conductivity, and hence on the ohmic heating by the return current that neutralizes the current in injected electron beams, must also be considered. Using radiative hydrodynamic simulations, in conjunction with thermal and electrical conductivities modified from their collisional values by turbulent processes, we model the heating rate along a flare loop. We derive the resulting temperature, pressure, velocity, and density profiles, and use them to calculate quantities such as the differential emission measure (DEM) and the emitted X-ray spectrum. For high levels of turbulence, the combination of high electrical resistivity and low thermal conductivity acts to create and sustain a region of very large temperature near the loop apex, creating a large overpressure that acts to suppress the upward evaporation of chromospheric material. Further, the associated large temperature gradients result in a reduction of the DEM at temperatures from 105 K to 107 K. The hard X-ray spectrum at high energies is reduced due to a lower electron flux reaching the chromosphere, but at low energies, it is enhanced due to thermal emission from the very hot coronal plasma. We assess the extent to which these results can be used to constrain the nature and role of turbulent motions in the flare volume.

Keywords: Solar atmosphere, Solar flares, Solar coronal loops, Solar x-ray emission, Solar activity
SCExAO/CHARIS Spectroscopic Characterization of Cloudy L/T Transition Companion Brown Dwarf HIP 93398 B. Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Y. Li et al. (2023), as part of an informed survey using the Hipparcos–Gaia Catalog of Accelerations. This object was previously classified as a T6 dwarf based on its luminosity, with its independently derived age and dynamical mass in tension with existing models of brown dwarf evolution. Spectral typing via empirical standard spectra, temperatures derived by fitting substellar atmosphere models, and J ‑ H, J ‑ K and   colors all suggest that this object has a substantially higher temperature and luminosity, consistent with classification as a late-L dwarf near the L/T transition (T =   K) with moderate to thick clouds possibly present in its atmosphere. When compared with the latest generation of evolution models that account for clouds with our revised luminosity and temperature for the object, the tension between the model-independent mass/age and model predictions is resolved.

Keywords: High contrast techniques, Brown dwarfs, L dwarfs, Coronagraphic imaging, Direct imaging, Late-type dwarf stars, High contrast spectroscopy, T dwarfs