Sazuna/UAT_keywords huggingface dataset:
The Global Structure of the Heliosphere. As the Sun moves through the local interstellar medium (LISM), it emits charged particles, creating the heliosphere occupied by the plasma of solar origin. Determining the structure of the heliosphere is a fundamental question that can be answered only by numerical simulations based on sophisticated theoretical models. Apart from the physics involved in the interaction of fully ionized, collisionless solar wind (SW) with the partially ionized, weakly collisional LISM, it is natural for humankind to speculate about our place of habitat as seen from a distance. This is especially germane now in light of recently observed astrospheres that possess substantially different shapes and structures. We present simulations of the SW–LISM interaction in a very large computational box, paying specific attention to modifications of the LISM properties caused by the presence of the heliosphere. Our results show that the heliosphere has a long heliotail, whose morphology is affected by the interstellar magnetic field pressure, so it acquires a sheetlike shape oriented along the plane formed by the interstellar magnetic field and velocity vectors in the unperturbed LISM. The SW–LISM boundary is subject to instabilities. A possibility is demonstrated of a quasi-parallel, slow-mode bow shock that affects some parts of the LISM flow. We demonstrate that the complex heliospheric structure affects the distribution of plasma and magnetic field in the LISM, resulting in a Galactic cosmic ray anisotropy consistent with the Tibet air shower experiment. We also analyze the effect of turbulence on the length of the heliotail and its ultimate destruction.

Keywords: Heliopause, Astrosphere interstellar medium interactions, Heliosphere, Interstellar plasma, Galactic cosmic rays, Interstellar medium
Spectral Properties of Globally Distributed ENA Fluxes across Diverse Regions of the Heliosphere. This study analyzes energetic neutral atom (ENA) spectral properties across distinct regions of globally distributed flux (GDF) sky maps, using Interstellar Boundary Explorer data from a full solar cycle, corrected for time dispersion. By time-shifting the data to the heliosheath using GDF source distances from D. B. Reisenfeld et al., we achieve a more accurate representation of heliosheath GDF energy spectra. We quantify ENA spectral characteristics, heliosheath line-of-sight-integrated proton pressure, and heliosheath proton temperature, comparing these to solar wind properties at 1 au and interplanetary scintillation-derived solar wind data. Our findings show that the spectral index is generally anticorrelated with heliosheath proton temperature and pressure, except in the central tail, where a partial positive correlation is observed. The lowest spectral index values occur when high-latitude heliosheath regions are dominated by fast solar wind from polar coronal holes. The south pole exhibits the flattest energy spectra due to plasma heating from both fast solar wind and a late-2014 pressure pulse. The central tail shows shorter variability (5–6 yr) for spectral index and heliosheath proton temperature, while proton pressure follows the 11 yr solar cycle. Most spectral shapes exhibit a "knee" distribution, peaking during solar maximum, with an "ankle" shape observed only at the south pole during solar cycle transitions. Asymmetry in proton pressure in the lobes is driven by the draping effect of the local interstellar magnetic field. This study provides insights into the energetic properties of GDF across the heliosphere, enhancing our understanding of the heliospheric environment.

Keywords: Heliosphere
Prospects for EMRI/MBH Parameter Estimation Using Quasiperiodic Eruption Timings: Short-timescale Analysis. Quasiperiodic eruptions (QPEs) are luminous, recurring X-ray outbursts from galactic nuclei, with timescales of hours to days. While their origin remains uncertain, leading models invoke accretion disk instabilities or the interaction of a massive black hole (MBH) with a lower-mass secondary in an extreme mass ratio inspiral (EMRI). EMRI scenarios offer a robust framework for interpreting QPEs by characterizing observational signatures associated with the secondary's orbital dynamics. This, in turn, enables extraction of the MBH/EMRI physical properties and provides a means to test the EMRI scenario, distinguishing models and addressing the question: what can QPE timings teach us about MBHs and EMRIs? In this study, we employ analytic expressions for Kerr geodesics to efficiently resolve the trajectory of the secondary object and perform GPU-accelerated Bayesian inference to assess the information content of QPE timings. Using our inference framework, referred to as QPE-FIT (Fast Inference with Timing; https://github.com/joheenc/QPE-FIT/tree/main), we explore QPE timing constraints on astrophysical parameters, such as EMRI orbital parameters and MBH mass/spin. We find that mild-eccentricity EMRIs (e ∼ 0.1–0.3) can constrain MBH mass and EMRI semimajor axis/eccentricity to the 10% level within tens of orbital periods, while MBH spin is unconstrained for the explored semimajor axes ≥100Rg and monitoring baselines  O (10–100) orbits. Introducing a misaligned precessing disk generally degrades inference of EMRI orbital parameters, but can constrain disk precession properties within 10%–50%. This work both highlights the prospect of QPE observations as dynamical probes of galactic nuclei and outlines the challenge of doing so in the multimodal parameter space of EMRI–disk collisions.

Keywords: Supermassive black holes, X-ray transient sources, Bayesian statistics, Gravitational waves
DESI Emission-line Galaxies: Clustering Dependence on Stellar Mass and [O II] Luminosity. We measure the projected two-point correlation functions of emission-line galaxies (ELGs) from the Dark Energy Spectroscopic Instrument One-Percent Survey and model their dependence on stellar mass and [O II] luminosity. We select ∼180,000 ELGs with redshifts of 0.8 &lt; z &lt; 1.6, and define 27 samples according to cuts in redshift and both galaxy properties. Following a framework that describes the conditional [O II] luminosity─stellar mass distribution as a function of halo mass, we simultaneously model the clustering measurements of all samples at fixed redshift. Based on the modeling result, most ELGs in our samples are classified as central galaxies, residing in halos of a narrow mass range with a typical median of ∼1012.2−12.4 h−1 M⊙. We observe a weak dependence of clustering amplitude on stellar mass, which is reflected in the model constraints and is likely a consequence of the 0.5 dex measurement uncertainty in the stellar mass estimates. The model shows a trend between galaxy bias and [O II] luminosity at high redshift (1.2 &lt; z &lt; 1.6) that is otherwise absent at lower redshifts.

Keywords: Cosmology, Galaxy dark matter halos, Galaxies, Large-scale structure of the universe
A Detection of Helium in the Bright Superluminous Supernova SN 2024rmj. We present extensive ultraviolet, optical, and near-infrared (NIR) photometric and spectroscopic observations of the nearby hydrogen-poor superluminous supernova (SLSN-I) SN 2024rmj at z = 0.1189. SN 2024rmj reached a peak absolute magnitude of Mg ≍ −21.9, placing it at the luminous end of the SLSN-I distribution. The light curve exhibits a pronounced prepeak bump (≍60 days before the main peak) and a postpeak bump (≍55 days after the main peak). The bulk of the light curve is otherwise well fit by a magnetar spin-down model, with typical values (spin: ≍2.1 ms; magnetic field: ≍6 × 1013 G; ejecta mass: ≍12 M⊙). The optical spectra exhibit characteristic SLSN-I features and evolution, but with a relatively high velocity of ≍8000 km s−1 postpeak. Most significantly, we find a clear detection of helium in the NIR spectra at He Iλ1.083 μm and λ2.058 μm, blueshifted by ≍15,000 km s−1 (13 days before peak) and ≍13,000 km s−1 (40 days after peak), indicating that helium is confined to the outermost ejecta; based on these NIR detections, we also identify likely contribution from He Iλ5876 in the optical spectra on a similar range of timescales. This represents the most definitive detection of helium in a bright SLSN-I to date, and indicates that progenitors with a thin helium layer can still explode as SLSNe.

Keywords: Type Ic supernovae, Core-collapse supernovae, Helium-rich stars, Transient sources, Time domain astronomy, Spectroscopy, Supernovae, Near infrared astronomy
Radio Variability in Recently Quenched Galaxies: The Impact of Tidal Disruption Event or Active Galactic Nucleus-Driven Outflows. Outflows and jets launched from the nuclei of galaxies emit radio synchrotron emission that can be used to study the impact of accretion energy on the host galaxy. The decades-long baseline now enabled by large radio surveys allows us to identify cases where new outflows or jets have been launched. Here, we present the results of a targeted Very Large Array program observing four poststarburst galaxies that have brightened significantly in radio emission over the past ∼20 yr. We obtain quasi-simultaneous observations in five bands (1─18 GHz) for each source. We find peaked spectral energy distributions, indicative of self-absorbed synchrotron emission. While all four sources have risen significantly over the past ∼20 yr in the 1─2 GHz band, two also show clear recent flares in the 2─4 GHz band. These sources are less luminous than typical peaked-spectrum radio active galactic nucleus (AGN). It remains unclear whether these sources are low luminosity analogs of the peaked radio AGN from accreted gas, or driven by tidal disruption events with missed optical flares. Regardless of the source of the accreted material, these newly launched outflows contain sufficient energy to drive the molecular gas outflows observed in poststarburst galaxies and to drive turbulence, suppressing star formation.

Keywords: Extragalactic radio sources, Supermassive black holes, Post-starburst galaxies, E+A galaxies
High-sensitivity Molecular Line Observations toward the L1544 Prestellar Core Challenge Current Models. The increased sensitivity and spectral resolution of observed spectra toward the prestellar core L1544 are challenging the current physical and chemical models. With the aim of further constraining the structure of L1544 as well as assessing the completeness of chemical networks, we turn to radiative transfer modeling of observed molecular lines toward this source. We obtained high-sensitivity and high spectral resolution observations of HCO+ (J = 1─0), CS (J = 2─1), C34S (J = 2─1), H2CO (J Ka,Kc  = 21,2─11,1), c-C3H2 (J Ka,Kc  = 21,2─10,1), SO (N, J = 2, 3─1, 2), and 34SO (N, J = 2, 3─1, 2) with the IRAM 30 m telescope toward the dust peak of L1544. A non─local thermodynamic equilibrium radiative transfer code is coupled to the Markov Chain Monte Carlo method to model the observations. We find that with just one transition for each isotope, the modeling cannot find a global minimum that fits the observations. The derived fractional abundance profiles are compared to those computed with chemical models. The observed transitions trace gas components with distinct dynamics at different distances along the radius of the core. Moreover, the results evidence a poor reproduction of sulfur chemistry by chemical modeling and stress the need to include a more consistent S-depletion process to accurately reproduce the S-chemistry toward dense cores. *Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

Keywords: Interstellar molecules, Dense interstellar clouds, Astrochemistry, Star formation, Radiative transfer
Surface Composition of Asteroid 269 Justitia: Insights from Spectral Mixture Modeling. Asteroid (269) Justitia is one of the more unusual asteroids in the main belt due to its extremely red spectral slope at visible and near infrared (VNIR) wavelengths. While the surface composition of (269) Justitia remains uncertain due to a lack of diagnostic absorption features in the VNIR region, intriguing clues to its nature are provided by recent mid- and thermal-infrared wavelength observations (MIR and TIR, respectively). In the VNIR, no identifiable analogs to Justitia can be found among the known meteorites. Instead, the best spectral matches come from Trans-Neptunian Objects (TNOs), possibly suggesting a genetic relationship with those bodies. On the other hand, recent TIR emissivity spectra reveal the likely presence of fine-grained anhydrous silicates on Justitia's surface, possibly inconsistent with a TNO origin. To explore this issue, we used a radiative transfer mixing model to investigate the spectral nature of Justitia in the VNIR and TIR. In the VNIR, our results are consistent with mixtures of space weathered silicates and carbonaceous material, though the presence of complex organics cannot be ruled out. In the TIR, our results favor either carbonaceous material or a mixture of space-weathered silicates and carbonaceous components. The best spectral match to Justitia's spectra was found by blending carbonaceous material with moderate to extensively space-weathered silicates. This combination could, in turn, indicate a potential collision between silicate-rich and carbonaceous bodies during the early history of Justitia.

Keywords: Surface composition, Asteroids
Exploration of the Outer Envelope of the K-giant Star Beta Cet<SUP></SUP>. Investigating the atmospheres of giants and supergiants is critical to expanding our knowledge of stellar life cycles, galaxy formation, and the origin of material that forms exoplanets. This paper presents the analysis of the evolved K-type giant β Cet using high-quality spectral data collected by the Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS), including an ultraviolet atlas with line identifications that will support future studies of cool, evolved stars. Beta Cet exhibits chromosphere emission, transition region diagnostics, and coronal X-ray flux, placing it near the Linsky─Haisch dividing line that separates objects with strong coronal signatures from the cooler giants and supergiants with massive stellar winds. The transition region in β Cet produces clear features in the STIS spectra that are formed at  logT&lt;  5.40 K, in addition to the highly ionized Fe XXIλ1354. It is stronger and more dominant than observed in the K5III hybrid star γ Dra, with a line surface flux as much as 2─3 orders of magnitude greater. The majority of the transition region lines are significantly broader than expected from thermal motion alone, and this nonthermal broadening appears to increase with formation temperature. The nonthermal width of the C IV and Si IV doublets is used to investigate the dominant heating mechanisms in β Cet's transition region. We find that the radiative losses observed in the ultraviolet are balanced by an energy influx from sound waves and turbulence, while the Alfvén waves supported by a magnetic field are required to account for the reported X-ray flux. *The material is based upon work supported by NASA under award number 80GSFC24M0006.

Keywords: K giant stars, Stellar chromospheres, Emission line stars, Stellar winds
Testing the Young Fast Radio Burst Progenitor Hypothesis: A Crossmatch of Catalog-1 CHIME Bursts with Historic Local Universe Supernovae. Fast radio bursts (FRBs) are among the most energetic and enigmatic transients in the radio sky, with mounting evidence suggesting newborn, highly magnetized neutron stars formed in core-collapse supernovae (CCSNe) as their sources. A definitive spatial association between an FRB and a historic CCSN would confirm this link and tightly constrain young neutron-star source models. Here we report on the first systematic crossmatching of 886 spectroscopically classified CCSNe in the local Universe (z ≤ 0.043) against 241 CHIME/FRB Catalog 1 events, applying rigorous spatial, dispersion measure (DM), and scattering time (τ) criteria. We identify four positional overlaps, all consistent with a chance alignment; however, one pair, FRB 20190412B─SN 2009gi, also satisfies independent host-DM and τ constraints, making it a promising candidate for targeted follow-up. Next, we search for compact (persistent or transient) radio emission at all matched supernova sites using multiepoch Very Large Array Sky Survey data and detect none. Treating every CCSN sight line as a nondetection, we derive Poisson upper limits on the FRB burst rate at these locations, which lie well below the rates observed for the most active repeaters unless their activity is heavily suppressed by beaming, intermittency, or residual free─free absorption. We then develop a galaxy-integrated FRB-rate model that incorporates an intrinsic spectral index, secular magnetar-activity decay, and frequency-dependent free─free opacity. Applying this formalism to existing FRB data shows that reproducing the observed CHIME/CRAFT all-sky rate ratio requires a steep decline in magnetar burst rate with age. Finally, our work underscores the necessity of subarcsecond localizations and multiwavelength follow-up to definitively test the young neutron star source hypothesis.

Keywords: Magnetars, Supernovae, Radio transient sources
Probing the Turbulent Corona and Heliosphere Using Radio Spectral Imaging Observation during the Solar Conjunction of the Crab Nebula. Measuring plasma parameters in the upper solar corona and inner heliosphere is challenging because of the region's weakly emissive nature and inaccessibility for most in situ observations. Radio imaging of broadened and distorted background astronomical radio sources during solar conjunction can provide unique constraints for the coronal material along the line of sight. In this study, we present radio spectral imaging observations of the Crab Nebula (Tau A) from 2024 June 9 to June 22 when it was near the Sun with a projected heliocentric distance of 5–27 solar radii, using the Owens Valley Radio Observatory's Long Wavelength Array at multiple frequencies in the 30–80 MHz range. The imaging data reveal frequency-dependent broadening and distortion effects caused by anisotropic wave propagation through the turbulent solar corona at different distances. We analyze the brightness, size, and anisotropy of the broadened images. Our results provide detailed observations showing that the eccentricity of the unresolved source increases as the line of sight approaches the Sun, suggesting a higher anisotropic ratio of the plasma turbulence closer to the Sun. In addition, the major axis of the elongated source is consistently oriented in the direction perpendicular to the radial direction, suggesting that the turbulence-induced scattering effect is more pronounced in the direction transverse to the coronal magnetic field. Lastly, when the source undergoes large-scale refraction as the line of sight passes through a streamer, the apparent source exhibits substructures at lower frequencies. This study demonstrates that observations of celestial radio sources with lines of sight near the Sun provide a promising method for measuring turbulence parameters in the inner heliosphere.

Keywords: Radio astrometry, Solar corona
Joint Analysis of H I Absorption Zeeman Measurements and the Morphology of Filamentary H I Emission. We present a joint analysis of H I absorption Zeeman measurements and the morphology of filamentary H I emission to investigate the 3D structure of the magnetic field in the diffuse neutral interstellar medium. Our analysis is based on the Arecibo Millennium Survey and new data from the Five-hundred-meter Aperture Spherical radio Telescope toward radio sources 3C 75, 3C 207, and 3C 409. Toward 3C 409, we make a 4σ Zeeman detection and infer BLOS = 9.1 ± 1.9 μG, in agreement with Arecibo results. We quantify the dispersion of H I filaments at the locations and velocities of Zeeman components using GALFA-H I narrow-channel emission maps. Focusing on a subsample of 42 spectrally distinct components, we find a weak but statistically significant positive correlation (Spearman ρ = 0.3, p = 0.01) between ∣BLOS∣ and the circular variance of H I filament orientation angles. To examine its origin, we characterize the environments probed by H I absorption using dust emission, 3D dust maps, OH absorption, and CO emission. We find evidence that existing H I absorption Zeeman measurements trace magnetic fields that are coherent on parsec scales, probe primarily local gas (100─500 pc, often at distances consistent with the Local Bubble wall), and exhibit systematic differences in the magnitude of BLOS. We attribute the correlation between Zeeman measurements and filamentary H I morphology to large-scale variations in magnetic field strength and/or inclination angle across different Galactic environments, which could arise due to the Local Bubble geometry or enhanced total field strength in denser regions.

Keywords: Radio spectroscopy, Spectropolarimetry, Interstellar filaments, Neutral hydrogen clouds, Interstellar magnetic fields, Cold neutral medium
Examining Active Galactic Nucleus UV/Optical Variability beyond the Simple Damped Random Walk. II. Insights from 22 yr Observations of SDSS, PS1, and ZTF. A damped random walk (DRW) process is often used to describe the temporal UV/optical continuum variability of active galactic nuclei (AGN). However, recent investigations have shown that this model fails to capture the full spectrum of AGN variability. In this work, we model the 22 yr long light curves of 21,767 quasars, spanning the redshift range 0.28 &lt; z &lt; 2.71, as a noise-driven damped harmonic oscillator (DHO) process. The light curves, in the optical g and r bands, are collected and combined from the Sloan Digital Sky Survey, the Panoramic Survey Telescope and Rapid Response System, and the Zwicky Transient Facility. A DHO process can be defined using four parameters, two for describing its long-term behavior/variability, and the other two for describing its short-term behavior/variability. We find that the best-fit DHO model describes the observed variability of our quasar light curves better than the best-fit DRW model. Furthermore, the best-fit DHO parameters exhibit correlations with the rest-frame wavelength, the Eddington ratio, and the black hole mass of our quasars. Based on the power spectral density shape of the best-fit DHOs and these correlations, we suggest that the observed long-term variability of our quasars can be best explained by accretion rate or thermal fluctuations originating from the accretion disk, and the observed short-term variability can be best explained by reprocessing of X-ray variability originating from the corona. The additional information revealed by DHO modeling emphasizes the need to go beyond DRW when analyzing AGN light curves delivered by next-generation wide-field time-domain surveys.

Keywords: Supermassive black holes, Sky surveys, Quasars, Active galactic nuclei, Red noise, Time series analysis