Sazuna/UAT_keywords huggingface dataset:
A Comparative Analysis of Scale-invariant Phenomena in Repeating Fast Radio Bursts and Glitching Pulsars. The recent discoveries of a remarkable glitch/antiglitch accompanied by fast radio burst (FRB)-like bursts from the Galactic magnetar SGR J1935+2154 have revealed the physical connection between the two. In this work, we study the statistical properties of radio bursts from the hyperactive repeating source FRB 20201124A and of glitches from the pulsar PSR B1737–30. For FRB 20201124A, we confirm that the probability density functions of fluctuations of energy, peak flux, duration, and waiting time well follow the Tsallis q-Gaussian distribution. The derived q values from q-Gaussian distribution keep approximately steady for different temporal interval scales, which indicates that there is a common scale-invariant structure in repeating FRBs. Similar scale-invariant properties can be found in PSR B1737–30's glitches, implying an underlying association between the origins of repeating FRBs and pulsar glitches. These statistical features can be well understood within the same physical framework of self-organized criticality systems.

Keywords: Radio bursts, Pulsars, Radio transient sources
Uncovering an Excess of X-Ray Point Sources in the Halos of Virgo Late-type Galaxies. We present a systematic search for extraplanar X-ray point sources around 19 late-type, highly inclined disk galaxies residing in the Virgo cluster, based on archival Chandra observations reaching a source detection sensitivity of L(0.5–8 keV) ∼ 1038 erg s‑1. Based on the cumulative source surface density distribution as a function of projected vertical distance from the disk midplane, we identify a statistically significant (∼3.3σ) excess of ∼20 X-ray sources within a projected vertical off-disk distance of  0.‧92–2.‧5  (∼4.4–12 kpc), the presence of which cannot be explained by the bulk stellar content of the individual galaxies, nor by the cosmic X-ray background. On the other hand, there is no significant evidence for an excess of extraplanar X-ray sources in a comparison sample of field late-type edge-on galaxies, for which Chandra observations reaching a similar source detection sensitivity are available. We discuss the possible origins for the observed excess, including low-mass X-ray binaries (LMXBs) associated with globular clusters, supernova-kicked LMXBs, and high-mass X-ray binaries born in recent star formation induced by ram pressure stripping of the disk gas, as well as a class of intracluster X-ray sources previously identified around early-type member galaxies of Virgo. We find that none of these X-ray populations can naturally dominate the observed extraplanar excess, although supernova-kicked LMXBs and the effect of ram pressure are most likely relevant.

Keywords: X-ray astronomy, X-ray binary stars, Late-type galaxies, Disk galaxies, Virgo Cluster
Discovery of a Proto–White Dwarf with a Massive Unseen Companion. We report the discovery of SDSS J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive (&gt;1 M ⊙ at 2σ confidence) companion with a period of 36 hr. We use a combination of spectroscopy, including data from the ongoing fifth-generation Sloan Digital Sky Survey (SDSS-V), and photometry to measure the stellar parameters of the primary pre-ELM WD. The lightcurve of the primary WD exhibits ellipsoidal variation, which we combine with radial velocity data and PHOEBE binary simulations to estimate the mass of the invisible companion. We find that the primary WD has mass M 1 =  0.18‑0.02+0.02  M ⊙ and the unseen secondary has mass M 2 =  1.19‑0.14+0.21  M ⊙. The mass of the companion suggests that it is most likely a near-Chandrasekhar-mass WD or a neutron star. It is likely that the system recently went through a Roche lobe overflow from the visible primary onto the invisible secondary. The dynamical configuration of the binary is consistent with the theoretical evolutionary tracks for such objects, and the primary is currently in its contraction phase. The measured orbital period puts this system on a stable evolutionary path which, within a few gigayears, will lead to a contracted ELM WD orbiting a massive compact companion.

Keywords: Neutron stars, White dwarf stars, Binary stars, Low mass stars
The Coupled Impacts of Atmospheric Composition and Obliquity on the Climate Dynamics of TRAPPIST-1e. Planets in multiplanet systems are expected to migrate inward as near-resonant chains, thus allowing them to undergo gravitational planet–planet interactions and possibly maintain a nonzero obliquity. The TRAPPIST-1 system is in such a near-resonant configuration, making it plausible that TRAPPIST-1e has a nonzero obliquity. In this work, we use the ExoCAM general circulation model to study the possible climates of TRAPPIST-1e at varying obliquities and atmospheric compositions. We vary obliquity from 0° to 90° and the partial pressure of carbon dioxide from 0.0004 bar (modern Earth-like) to 1 bar. We find that models with a higher obliquity are hotter overall and have a smaller day–night temperature contrast than the lower-obliquity models, which is consistent with previous studies. Most significantly, the superrotating high-altitude jet becomes subrotating at high obliquity, thus impacting cloud and surface temperature patterns. As the amount of carbon dioxide increases, the climate of TRAPPIST-1e becomes hotter, cloudier, and less variable. From modeled thermal phase curves, we find that the impact of obliquity could potentially have observable consequences due to the effect of cloud coverage on the outgoing longwave radiation.

Keywords: Extrasolar rocky planets, Exoplanets, Exoplanet atmospheric dynamics, Habitable planets, Exoplanet atmospheres
Historical Fermi All-sky Variability Analysis of Galactic Flares. The Fermi All-sky Variability Analysis (FAVA) provides a photometric alternative for identifying week-long gamma-ray flares across the entire sky while being independent of any diffuse Galactic or isotropic emission model. We reviewed 779 weeks of Fermi Large Area Telescope data analyzed by FAVA to estimate the rate and origin of Galactic gamma-ray flares, and to search for new variable Galactic gamma-ray transients. We report an estimated yearly rate of ∼8.5 Galactic gamma-ray flares yr–1, with ∼1 flare yr–1 coming from unknown sources. Out of the known gamma-ray sources that are spatially coincident with these detected flares, we report gamma-ray flares for six of them for the first time. All six are classified as pulsars, or a source of unknown nature but which positionally overlaps with known supernova remnants or pulsar wind nebulae (PWNe). This potentially means these sites are tentative candidates to be the second known site of a variable gamma-ray PWN, after the famous Crab Nebula's PWN. Additionally, we identify nine unassociated flares that are unlikely to have originated from known gamma-ray sources.

Keywords: High energy astrophysics, Millisecond pulsars, High mass x-ray binary stars, Transient sources, Pulsars, Supernova remnants, Pulsar wind nebulae, Gamma-ray astronomy, Gamma-ray transient sources
The Relation between the Cool-core Radius and the Host Galaxy Clusters: Thermodynamic Properties and Cluster Mass. We present a detailed study of cool-core systems in a sample of four galaxy clusters (RXCJ1504.1-0248, A3112, A4059, and A478) using archival X-ray data from the Chandra X-ray Observatory. Cool cores are frequently observed at the centers of galaxy clusters and are considered to be formed by radiative cooling of the intracluster medium (ICM). Cool cores are characterized by a significant drop in the ICM temperature toward the cluster center. We extract and analyze X-ray spectra of the ICM to measure the radial profiles of the ICM thermodynamic properties, including temperature, density, pressure, entropy, and radiative cooling time. We define the cool-core radius as the turnover radius in the ICM temperature profile and investigate the relation between the cool-core radius and the properties of the host galaxy clusters. In our sample, we observe that the radiative cooling time of the ICM at the cool-core radius exceeds 10 Gyr, with RXCJ1504.1-0248 exhibiting a radiative cooling time of  32‑11+5  Gyr at its cool-core radius. These results indicate that not only radiative cooling but also additional mechanisms, such as gas sloshing, may play an important role in determining the size of cool cores. Additionally, we might find that the best-fit relation between the cool-core radius and the cluster mass (M 500) is consistent with a linear relation. Our findings may suggest that cool cores are linked to the evolution of their host galaxy clusters.

Keywords: Galaxy clusters, Intracluster medium, X-ray astronomy
Importance of Cosmic-Ray Propagation on Sub-GeV Dark Matter Constraints. We study sub-GeV dark matter (DM) particles that may annihilate or decay into Standard Model particles producing an exotic injection component in the Milky Way that leaves an imprint in both photon and cosmic-ray (CR) fluxes. Specifically, the DM particles may annihilate or decay into e + e −, μ + μ −, or π + π − and may radiate photons through their e ± products. The resulting e ± products can be directly observed in probes such as Voyager 1. Alternatively, the e ± products may produce bremsstrahlung radiation and upscatter the low-energy Galactic photon fields via the inverse Compton process, generating a broad emission from X-ray to γ-ray energies observable in experiments such as XMM-Newton. We find that we get a significant improvement in the DM annihilation and decay constraints from XMM-Newton (excluding thermally averaged cross sections of 10−31 cm3 s−1 ≲ 〈σ v〉 ≲ 10−26 cm3 s−1 and decay lifetimes of 1026 s ≲ τ ≲ 1028 s, respectively) by including best-fit CR propagation and diffusion parameters. This yields the strongest astrophysical constraints for this mass range of DM of 1 MeV to a few GeV and even surpasses cosmological bounds across a wide range of masses as well.

Keywords: Galactic cosmic rays, Dark matter
Testing MOND on Small Bodies in the Remote Solar System. Modified Newtonian dynamics (MOND), which postulates a breakdown of Newton's laws of gravity/dynamics below some critical acceleration threshold, can explain many otherwise puzzling observational phenomena on galactic scales. MOND competes with the hypothesis of dark matter, which successfully explains the cosmic microwave background and large-scale structure. Here we provide the first solar system test of MOND that probes the subcritical acceleration regime. Using the Bekenstein–Milgrom "aquadratic Lagrangian" (or AQUAL) formulation, we simulate the evolution of myriads of test particles (planetesimals or comets) born in the trans-Neptunian region and scattered by the giant planets over the lifetime of the Sun to heliocentric distances of 102–105 au. We include the effects of the Galactic tidal field and passing stars. While Newtonian simulations reproduce the distribution of binding energies of long-period and Oort-cloud comets detectable from Earth, MOND-based simulations do not. This conclusion is robust to plausible changes in the migration history of the planets, the migration history of the Sun, the MOND transition function, effects of the Sun's birth cluster, and the fading properties of long-period comets. For the most popular version of AQUAL, characterized by a gradual transition between the Newtonian and MOND regimes, our MOND-based simulations also fail to reproduce the orbital distribution of trans-Neptunian objects in the detached disk (perihelion q &gt; 38 au). Our results do not rule out some MOND theories more elaborate than AQUAL, in which non-Newtonian effects are screened on small spatial scales, at small masses, or in external gravitational fields comparable in strength to the critical acceleration.

Keywords: Gravitation, Oort cloud, Non-standard theories of gravity, Comet dynamics, Detached objects, Trans-Neptunian objects, Modified Newtonian dynamics
FEASTS Combined with Interferometry. I. Overall Properties of Diffuse H I and Implications for Gas Accretion in Nearby Galaxies. We present a statistical study of the properties of diffuse H I in 10 nearby galaxies, comparing the H I detected by the single-dish telescope FAST (FEASTS program) and the interferometer Very Large Array (THINGS program), respectively. The THINGS observation missed H I with a median of 23% due to the short-spacing problem of interferometry and limited sensitivity. We extract the diffuse H I by subtracting the dense H I, which is obtained from the THINGS data with a uniform flux-density threshold, from the total H I detected by FAST. Among the sample, the median diffuse-H I fraction is 34%, and more diffuse H I is found in galaxies exhibiting more prominent tidal-interaction signatures. The diffuse H I we detected seems to be distributed in disk-like layers within a typical thickness of 1 kpc, different from the more halo-like diffuse H I detected around NGC 4631 in a previous study. Most of the diffuse H I is cospatial with the dense H I and has a typical column density of 1017.7–1020.1 cm‑2. The diffuse and dense H I exhibit a similar rotational motion, but the former lags by a median of 25% in at least the inner disks, and its velocity dispersions are typically twice as high. Based on a simplified estimation of circumgalactic medium properties and assuming pressure equilibrium, the volume density of diffuse H I appears to be constant within each individual galaxy, implying its role as a cooling interface. Comparing with existing models, these results are consistent with a possible link between tidal interactions, the formation of diffuse H I, and gas accretion.

Keywords: Galaxy formation, Galaxy evolution, Interstellar atomic gas, Circumgalactic medium
The SDSS-V Black Hole Mapper Reverberation Mapping Project: C IV Broad Absorption Line Acceleration in the Quasar SBS 1408+544. We present the results of an investigation of a highly variable C IV broad absorption line (BAL) feature in spectra of the quasar SBS 1408+544 (z = 2.337) that shows a significant shift in velocity over time. This source was observed as a part of the Sloan Digital Sky Survey (SDSS) Reverberation Mapping project and the SDSS-V Black Hole Mapper Reverberation Mapping project, and has been included in two previous studies, both of which identified significant variability in a high-velocity C IV BAL on timescales of just a few days in the quasar rest frame. Using ∼130 spectra acquired over 8 yr of spectroscopic monitoring with SDSS, we have determined that this BAL is not only varying in strength, but is also systematically shifting to higher velocities. Using cross-correlation methods, we measure the velocity shifts (and corresponding acceleration) of the BAL over a wide range of timescales, measuring an overall velocity shift of  Δv=‑683‑84+89  km s‑1 over the 8 yr monitoring period. This corresponds to an average rest-frame acceleration of a = 1.04 ‑0.13+0.14  cm s‑2, though the magnitude of the acceleration on shorter timescales is not constant throughout. We place our measurements in the context of BAL-acceleration models and examine various possible causes of the observed velocity shift.

Keywords: Active galactic nuclei, Quasars, Broad-absorption line quasar
Polarization Properties of 128 Nonrepeating Fast Radio Bursts from the First CHIME/FRB Baseband Catalog. We present a 400–800 MHz polarimetric analysis of 128 nonrepeating fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, increasing the total number of FRB sources with polarization properties by a factor of ∼3. A total of 89 FRBs have &gt;6σ linearly polarized detections, 29 FRBs fall below this significance threshold and are deemed linearly unpolarized, and for 10 FRBs, the polarization data are contaminated by instrumental polarization. For the 89 polarized FRBs, we find Faraday rotation measure (RM) amplitudes, after subtracting approximate Milky Way contributions, in the range 0.5–1160 rad m‑2 with a median of 53.8 rad m‑2. Most nonrepeating FRBs in our sample have RMs consistent with Milky Way–like host galaxies, and their linear polarization fractions range from ≤10% to 100% with a median of 63%. We see marginal evidence that nonrepeating FRBs have more constraining lower limits than repeating FRBs for the host electron-density-weighted line of sight magnetic field strength. We classify the nonrepeating FRB polarization position angle (PA) profiles into four archetypes: (i) single component with constant PA (57% of the sample), (ii) single component with variable PA (10%), (iii) multiple components with a single-constant PA (22%), and (iv) multiple components with different or variable PAs (11%). We see no evidence for population-wide frequency-dependent depolarization, and, therefore, the spread in the distribution of fractional linear polarization is likely intrinsic to the FRB emission mechanism. Finally, we present a novel method to derive redshift lower limits for polarized FRBs without host galaxy identification and test this method on 20 FRBs with independently measured redshifts.

Keywords: Radio bursts, Polarimetry, Radio transient sources
Investigating the Ultracompact X-Ray Binary Candidate SLX 1735-269 with NICER and NuSTAR. We present two simultaneous NICER and NuSTAR observations of the ultracompact X-ray binary (UCXB) candidate SLX 1735‑269 while the source was in two different spectral states. Using various reflection modeling techniques, we find that XILLVERCO, a model used for fitting X-ray spectra of UCXBs with high carbon and oxygen abundances is an improvement over RELXILL or RELXILLNS, which instead contains solar-like chemical abundances. This provides indirect evidence in support of the source being ultracompact. We also use this reflection model to get a preliminary measurement of the inclination of the system,  i=57‑7+23  degrees. This is consistent with our timing analysis, where a lack of eclipses indicates an inclination of i &lt; 80°. The timing analysis is otherwise inconclusive, and we cannot confidently measure the orbital period of the system.

Keywords: Low-mass x-ray binary stars, Neutron stars, X-ray binary stars
Properties of Galactic B[e] Supergiants. X. Refined Orbit and Fundamental Parameters of the HD 327083 Binary System. HD 327083 is a binary system that consists of two supergiant components and exhibits the B[e] phenomenon. In this paper, we report the determination of a new set of the system's fundamental parameters using a combination of photometric and spectroscopic data as well as the Gaia EDR3 distance. We found that the orbital period of the system is 107.68 ± 0.02 days. The spectral line content implies the effective temperatures of ≍7000 K and 25,400 ± 1400 K, while the photometric variations are consistent with the radii of ≍106 R ⊙ and ≍10 R ⊙ for the cool and hot components, respectively. The absorption lines of the cool component show a radial velocity semiamplitude of 48.3 ± 1.7 km s−1, similar to that of the emission lines that originate around the hot component. The inclination of the system to the line of sight is  47−20+17 °. Modeling of the system's evolutionary history suggests that the components have masses of ∼12.5 M ⊙ and currently undergo mass transfer between them. This configuration, which takes in heating of the surface of the cool component by the radiation from the hot one, can reproduce the photometric and spectroscopic data and is in agreement with previous infrared observations of the circumbinary disk. The results of this study further confirm the hypothesis that the reason for the presence of the B[e] phenomenon in most objects is a consequence of the evolution of various binary systems.

Keywords: Emission line stars, Binary stars, A stars
Equator to Pole Solar Chromospheric Differential Rotation Using Ca-K Features Derived from Kodaikanal Data. Differential rotation is one of the basic characteristics of the Sun, and it plays an important role in generating the magnetic fields and its activities. We investigated rotation rate using chromospheric features such as plages, enhanced network (EN), active network (AN), and quiet network (QN) separately (for the first time). The digitized Ca-K images from Kodaikanal Observatory for 1907–1996 are used to study rotation over 0°–80° latitudes at an interval of 10°. We find that plages and all types of networks exhibit the differential rotation of the chromosphere. Furthermore, the rotation rate shows a decreasing pattern as one move from the equator to the higher polar latitudes for all the features used in the study. At the equator the rotation rate (rotation period) is obtained to be ∼13.98° day‑1 (25.74 days), ∼13.91° day‑1 (25.88 days), ∼13.99° day‑1 (25.74 days), and ∼14.11° day‑1 (25.51 days) for plage, EN, AN, and QN areas, respectively. By analyzing how the area of chromospheric features varies over time, we can effectively map the Sun's rotation rate at all latitudes, including the polar regions. Interestingly, both plages and small-scale networks exhibit a similar differential rotation rate. This suggests these features likely rooted at the same layer below the visible surface of the Sun. Therefore, the long-term Ca-K data is very useful for studying the solar rotation rate at all latitudes including the polar regions.

Keywords: Solar chromosphere, Solar rotation, Solar differential rotation, Plages
Hot Gas Outflow Properties of the Starburst Galaxy NGC 4945. We analyze 330 ks of Chandra X-ray imaging and spectra of the nearby, edge-on starburst and Seyfert type 2 galaxy NGC 4945 to measure the hot gas properties along the galactic outflows. We extract and model spectra from 15 regions extending from ‑0.55 to +0.85 kpc above and below the galactic disk to determine the best-fit parameters and metal abundances. We find that the hot gas temperatures and number densities peak in the central regions and decrease along the outflows. These profiles are inconsistent with a spherical, adiabatically expanding wind model, suggesting the need to include mass loading and/or a nonspherical outflow geometry. We estimate the mass outflow rate of the hot wind to be 1.6 M ⊙ yr‑1. Emission from charge exchange is detected in the northern outflow, and we estimate it contributes 12% to the emitted, broadband (0.5–7 keV) X-ray flux.

Keywords: Galactic winds, Starburst galaxies
Spectropolarimetric Radio Imaging of Faint Gyrosynchrotron Emission from a CME: A Possible Indication of the Insufficiency of Homogeneous Models. The geo-effectiveness of coronal mass ejections (CMEs) is determined primarily by their magnetic fields. Modeling of gyrosynchrotron (GS) emission is a promising remote sensing technique to measure the CME magnetic field at coronal heights. However, faint GS emission from CME flux ropes is hard to detect in the presence of bright solar emission from the solar corona. With high dynamic-range spectropolarimetric meter wavelength solar images provided by the Murchison Widefield Array, we have detected faint GS emission from a CME out to ∼8.3 R ⊙, the largest heliocentric distance reported to date. High-fidelity polarimetric calibration also allowed us to robustly detect circularly polarized emission from GS emission. For the first time in the literature, Stokes V detection has jointly been used with Stokes I spectra to constrain GS models. One expects that the inclusion of polarimetric measurement will provide tighter constraints on the GS model parameters. Instead, we found that homogeneous GS models, which have been used in all prior works, are unable to model both the total intensity and circular polarized emission simultaneously. This strongly suggests the need for using inhomogeneous GS models to robustly estimate the CME magnetic field and plasma parameters.

Keywords: Spectropolarimetry, Solar physics, Solar radio emission, Solar coronal mass ejections, Polarimetry