Sazuna/UAT_keywords huggingface dataset:
A Search for Be Stars in Multiple Systems within the Solar Neighborhood. Be stars are widely considered to be the product of binary interaction. However, whether all Be stars are formed via binary interaction is unclear, and detailed estimates of the multiplicity of Be stars and characterization of their components are required. In this study, we present speckle observations of 76 Be stars taken using the Gemini North and South speckle imagers spanning angular separations of 20 mas─1 .″ 2, reaching contrasts ∆m ∼ 5─6 mag at separations around 0 .″ 1. We identify 11 (6 previously unreported) binaries having separations in the 10─1000 au range, and ∆m between 0.8 and 5 mag in our sample. Using archival data to search for components outside our visibility range, we add further multiples (16), which include three triples, leading to a total of 24 multiple systems. Our findings rule out a multiplicity fraction &gt;27% at the 3σ level within the speckle observations separation range and detection limits. Future homogeneous spectroscopic/interferometric observations are essential to probe the inner separations, and along with analysis of available astrometry can cover the entire separation range to characterize the multiplicity fraction, and evolutionary scenario of Be stars.

Keywords: Be stars, Binary stars, Speckle interferometry
The Hierarchical Dynamical State of Molecular Gas from 3 to 300 pc in NGC 253. Understanding how the dynamical state of the interstellar medium (ISM) changes across spatial scales can provide important insights into how the gas is organized and ultimately collapses to form stars. To this end, we present ALMA 12CO(2─1) observations at 7 pc (0 .″ 4) spatial resolution across a 1.4 kpc × 5.6 kpc ( 1.'3×1.'3 ) region located in the disk of the nearby (D = 3.5 Mpc), massive, star-forming galaxy NGC 253. We decompose this emission with a hierarchical, multiscale dendrogram algorithm to identify 2463 structures with deconvolved sizes ranging from ∼3 to 300 pc, complete to a limiting mass of 104 M⊙. By comparing the virial parameter of these structures against physical properties including size, mass, surface density, velocity dispersion, and hierarchical position, we carry out a comprehensive search for a preferred scale at which gravitationally bound structures emerge. Ultimately, we do not identify evidence of an emergent scale for bound objects in our data, nor do we find a significant correlation between the virial parameter and structure sizes. These findings suggest that simple observational estimates of gravitational binding cannot be used to define molecular clouds and emphasize the need for multiscale approaches to characterize the ISM.

Keywords: Molecular gas, Starburst galaxies, Giant molecular clouds, Star formation, Interstellar medium
The Interstellar Medium Conditions of a Strong Lyα Emitter at z = 8.279 from JWST: A Robust Lyman Continuum Leaker Candidate at the Epoch of Reionization. Making use of JWST NIRSpec and NIRCam data, we conduct a detailed analysis of GN-z8-LAE, a strong Lyα emitter at z = 8.279. We investigate the interstellar medium (ISM) conditions that enable the Lyα detection in this source at the Epoch of Reionization (EoR) and scrutinize GN-z8-LAE as an early reionizer. In agreement with previous results, we find that GN-z8-LAE is a young galaxy (age ∼10 Myr) with a lower stellar mass (M⋆ ∼ 107.66 M⊙) than most Lyα emitters (LAEs) at similar redshifts. The derived stellar-mass and star formation rate surface densities are  ΣM⋆∼355M⊙pc-2  and ΣSFR ∼ 88 M⊙ yr−1 kpc2, respectively. Our spectral analysis indicates that: the Lyα line peak has a small velocity offset ∆v = 133 ± 72 km s−1 with respect to the galaxy systemic redshift; C IV]/C III] ≍ 3.3; and the ISM is characterized by a hard ionization field, although no signatures of active galactic nuclei are present. Moreover, we report the presence of N III]λ1750 emission, implying supersolar N abundance, which makes GN-z8-LAE one of the first strong Lyα and nitrogen emitters at the EoR. Based on all these properties, we apply a wide range of methods to constrain the Lyman continuum escape fraction ( fescLyC ) of GN-z8-LAE and report  fescLyC&gt;14%  in all cases. Therefore, we conclude that GN-z8-LAE is a robust candidate for a Lyman continuum leaker at the EoR that is being caught at the moment of efficiently reionizing its surrounding medium.

Keywords: Infrared spectroscopy, Infrared astronomy, James Webb Space Telescope, Galaxy photometry, Galaxy evolution, Lyman-alpha galaxies, High-redshift galaxies
New Interpretation for the Orientation of the LMC's Gaseous Arms B and E Using ULLYSES. The Large Magellanic Cloud (LMC) has experienced disruption from tidal and ram-pressure forces as it travels through the halo of the Milky Way. In this project, we combine radio emission-line observations from the Galactic All Sky Survey and Galactic Australian Square Kilometre Array Pathfinder surveys with UV absorption-line observations from the Hubble Space Telescope Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program to trace the material in front of the LMC. Along our eight stellar sight lines near 30 Doradus, we observe gaseous structures likely associated with two arm-like features flowing in and around the LMC's disk. We detect the nearside gas in neutral, low-, and medium-ionization species. The lower-ionization species likely undergo both thermal and nonthermal broadening while the moderately ionized phase is influenced by more nonthermal processes. The total integrated column density of Al III decreases with increasing angular offset from 30 Doradus, with sight lines within ∆θ ≲ 0 .° 25 containing more moderately ionized gas. We demonstrate from a Gaussian decomposition technique on the H I emission that both arms likely trace an additional  ∼1.°0  in Galactic longitude toward the 30 Doradus region than previously predicted. We constrain the orientation of the arms by suggesting that they likely converge around  (l,b)=(280.°5,−31.°2)  and at least partially cross in front of the LMC. Our observations are consistent with two competing origins of the arms: (1) outflowing material is swept back by tidal and ram-pressure forces or (2) tidally stripped inflows fuel the ongoing stellar activity inside the LMC. Future studies are needed to distinguish between these scenarios. ∗Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract No. NAS5-26555.

Keywords: Galactic winds, Galaxy environments, Galaxy infall, Large Magellanic Cloud, Circumgalactic medium
Role of Sunspot Latitude versus Tilt in Determining the Polar Field and Amplitude of the Next Cycle: Cause of the Weak Solar Cycle 20. One prominent feature of the solar cycle is its irregular variation in its cycle strength, making it challenging to predict the amplitude of the next cycle. Studies show that fluctuations and nonlinearity in the process of generating poloidal field through the decay and dispersal of tilted sunspots produce variation in the solar cycle. The flux, latitudinal position, and tilt angle of sunspots are the primary parameters that determine the polar field and, thus, the next solar cycle strength. By analyzing the observed sunspots and polar field proxy, we show that the nonlinearity in the poloidal field generation becomes important for strong cycles. Except for strong cycles, we can reasonably predict the polar field at the end of the cycle (and thus the next cycle strength) using the total sunspot area alone. Combining the mean tilt angle and latitude positions with the sunspot area, we can predict the polar field of Cycles 15─24 (or the amplitude of sunspot Cycles 16─25) with reasonable accuracy, except for Cycle 23 for which the average tilt angle cannot predict the polar field. For Cycles 15─22, we show that the average tilt angle variation dominates over the latitude variation in determining the polar field of a cycle. In particular, the reduction of tilt in Cycle 19 was the primary cause of the following weak cycle (Cycle 20). Thus, we conclude that tilt quenching is essential in regulating the solar cycle strength in the solar dynamo.

Keywords: Solar cycle, Sunspots, Solar dynamo, Solar magnetic fields, Solar activity
Mitigating Random-phase Sampling Noise in the Cepheid Period─Luminosity Relation: A Cross-filter Consistency Approach. The period─luminosity (PL) relation is usually derived using time-averaged magnitudes, which require multiple-epoch observations to determine periods and adequately sample the light curves. Although single-epoch observations are more practical and require significantly less observational effort, they inherently introduce greater photometric scatter, leading to an increased dispersion in the derived PL relations. In this paper, we explore, in detail, a method that transforms single random-phase data to their mean-light values, using information obtained in other bands for the same Cepheid. This approach enables the accurate reconstruction of mean-light PL relations for wavelengths observed with space-based facilities, for instance, where the number of epochs per star makes simple averaging or template fitting less than optimal, with the latter requiring very high-precision periods for predictive phasing. While applying this technique across multiple bands, from optical to mid-IR, we focus particularly on widely separated bands covering the mid-IR to the optical. We showcase this method using the J band (as being observed by JWST) as the random-phase component. Our results show that this correction reduces the scatter of the PL relation in the J band by a factor of approximately 0.7×, equivalent to increasing the number of random-phase observations by a factor of 10, needed to obtain the same increase in precision as delivered here.

Keywords: Cepheid distance
Optically Overluminous Tidal Disruption Events: Outflow Properties and Implications for Extremely Relativistic Disruptions. Recent studies suggest that tidal disruption events (TDEs) with off-axis jets may manifest as optically overluminous events. To search for jet signatures at late times, we conducted radio observations of eight such optically overluminous (Mg,peak &lt; −20.8 mag) TDEs with the Very Large Array. We detect radio counterparts in four events. The observed radio luminosities (L6 GHz ∼ 1038─1039 erg s−1) are two orders of magnitude lower than those of on-axis jetted TDEs, and we find no evidence for off-axis jets within a rest-frame time of 3 yr. Two of them (AT2022hvp and AT2021aeou) exhibit evolving radio emission, consistent with synchrotron emission from non-relativistic outflows launched near the time of first optical light. Two events (AT2020ysg and AT2020qhs) show no statistically significant variability, which can be attributed to either non-relativistic outflows or pre-existing active galactic nuclei. Compared to a control sample of fainter TDEs with Mg,peak &gt; −20.5 mag observed at similar rest-frame timescales (trest ∼ 1.5 yr), our sample shows systematically more luminous radio emission, suggesting that optically overluminous TDEs may launch more powerful prompt non-relativistic outflows. We speculate that strong general relativistic effects near high-mass black holes (MBH ∼ 108 M⊙) may play a key role. These findings motivate further investigation into the nature of relativistic disruptions around massive black holes and the physical conditions necessary for jet formation.

Keywords: Supermassive black holes, Tidal disruption, Time domain astronomy, Radio transient sources
Gravitational Waves from Massive Black Hole Mergers in ASTRID: Predictions for LISA. We use the ASTRID cosmological simulation to forecast massive black hole (MBH) mergers detectable by Laser Interferometer Space Antenna (LISA) down to z = 0. ASTRID directly models MBH dynamical friction, allowing a realistic tracking of their trajectory. It also incorporates relatively low-mass MBH seeds down to 5 × 104M⊙, providing a more complete picture of LISA MBH mergers. We find that LISA MBH mergers initially have high eccentricities, peaking around e0 = 0.8 across all redshifts. Accounting for this boosts the event rate from 5.6 yr−1 (if circular orbits are assumed) to 10.5 yr−1. This enhancement is largely due to additional inspiral sources that will coalesce after LISA's observation, which constitute 46% of detected events. This underscores the importance of LISA's sensitivity to the early inspiral phase, especially for eccentric binaries that emit gravitational waves across a wider frequency band. Most LISA events in ASTRID arise from MBH ∼ 105−6 M⊙, low-redshift (z &lt; 2) and low-mass-ratio (q ∼ 0.01─0.1) mergers. Accounting for eccentricity broadens the detectable MBH mass range up to 109 M⊙ and shifts the peak of detectable mergers to a lower redshift zpeak = 0.8. This implies that the most massive LISA events may also be PTA sources. We predict LISA events to be in various galaxy environments, including many low-mass satellite galaxies. The electromagnetic (EM) counterparts of most LISA sources have active galactic nuclei (AGN) luminosities Lbol &gt; 1042 erg s−1, albeit only 1% with &gt;1044 erg s−1. The brightest AGN are those associated with the rare LISA/PTA events with MBH &gt; 108 M⊙.

Keywords: AGN host galaxies, Supermassive black holes, Galaxy mergers, Hydrodynamical simulations
The Hourglass-shaped Magnetic Fields and Dust Filaments in the HH 211 Protostellar Envelope. Magnetic fields influence the structure and evolution of protostellar systems; thus, understanding their role is essential for probing the earliest stages of star formation. We present Atacama Large Millimeter/submillimeter Array Band 3 and 6 polarized continuum observations at ∼0 .″ 5 resolution toward the Class 0 protostellar system HH 211. Three dust filaments (∼4000 au in length) are found in the HH 211 protostellar envelope, two of which are aligned with core-scale (∼10,000 au) magnetic fields detected by previous James Clerk Maxwell Telescope observations. This result suggests that the formation of the dust filaments may be influenced by magnetic fields. In the inner envelope (∼1000 au), we detect a clear hourglass-shaped magnetic field morphology near the protostar and toroidal fields along the outflow directions. We also estimate the line-of-sight averaged temperature and column density distributions in the inner envelope and find that the temperature is higher in the east, while the column density is enhanced in the southern and western regions. The southern dense regions of the inner envelope may trace either outflow cavity walls, due to their alignment with the outflow, or possible infalling channels in the midplane, given the close correspondence between the observed magnetic fields and the predicted infall trajectories.

Keywords: Observational astronomy, Polarimetry, Interstellar magnetic fields, Young stellar objects, Star formation, Protostars, Radio astronomy
Statistical Investigations of the Radial Interplanetary Magnetic Field Component Impact on the Magnetotail Current Sheet Structure of Mars: MAVEN Observations. In this study, we investigated the role of interplanetary magnetic field (IMF) orientation in controlling the location and structure of the current sheet (CS) in the Martian magnetotail. Based on carefully selected cases as well as statistical studies using the magnetic field and plasma data of Mars Atmosphere and Volatile EvolutioN from 2014 October to 2020 February, our work shows that the IMF orientation can systematically influence the magnetotail CS structure of Mars. Our results reveal a systematic dawn─dusk (Y-axis) asymmetry in CS positioning under different IMF orientations. Specifically, a sunward-directed IMF (cone angle &lt; 60°) shifts the CS toward the dusk (+Y) hemisphere, while a tailward-directed IMF (cone angle &gt; 120°) shifts it toward the dawn (−Y) hemisphere. Under cross-flow IMF conditions (70° &lt; cone angle &lt; 110°), no significant CS displacement is observed. This pattern persists even after accounting for possible confounding influences such as Martian crustal magnetic fields and solar EUV intensity. Our findings suggest that the cone angle of the IMF can systematically control the CS structure and magnetic lobes in the magnetotail of Mars. This IMF-controlled CS asymmetry has implications for understanding planetary ion escape and magnetotail dynamics at unmagnetized bodies.

Keywords: Space plasmas, Mars, Solar wind, Solar-planetary interactions, Planetary science, Planetary magnetospheres
Using LHASSO-observed Gamma-Ray Bursts to Study the Extragalactic Background Light. The extragalactic background light (EBL), a diffuse radiation field produced by all galaxies throughout cosmic history, plays a crucial role in the propagation of high-energy gamma-rays through photon─photon interactions. These interactions lead to characteristic absorption features in the observed TeV gamma-ray spectrum. Motivated by these effects, we analyze observations of GRB 221009A, the most energetic gamma-ray burst (GRB) ever detected by the Large High Altitude Air Shower Observatory, to investigate the EBL via gamma─gamma absorption signatures imprinted on the TeV spectrum. To minimize potential effects from Lorentz invariance violation and axion-like particles, we restrict our analysis to gamma rays with energies below 8 TeV. By comparing the modeled intrinsic spectra with the observed data, we constrain the spectral energy distribution of the EBL in the wavelength range of 0.1─40 μm. Our results are consistent with existing EBL models and observational limits derived from galaxy counts and infrared surveys. Furthermore, the inferred cosmic emissivity, which represents the integrated light from galaxies, is found to be primarily dominated by spiral-type galaxies.

Keywords: Gamma-ray bursts, Cosmic background radiation
Probing the Dust Torus Radius─Luminosity Relation: A WISE View. We present measurements of the dusty torus sizes of 51 active galactic nuclei (AGNs) with a redshift of z &lt; 0.8. Our analysis utilizes about 16 yr of optical photometric data of 146 AGNs from various time-domain surveys, including ASAS-SN, CRTS, and ZTF, along with 14 yr of infrared data in the W1 (∼3.4 μm) and W2 (∼4.6 μm) bands obtained from the Wide-Field Infrared Survey Explorer. The estimated dust torus size ranges from 1000 to 3000 days, using both the cross-correlation analysis and light-curve modeling through "MICA." The measured lag has been corrected by (1 + z)−0.37, to account for cosmological time dilation and the torus temperature-gradient scaling. We conduct a linear regression analysis for both the W1 and W2 bands to examine the radius─luminosity (R─LBOL) relationship under two conditions: one where the slope is fixed at 0.5 and one where it is allowed to vary. For the fixed slope of 0.5, we find the ratio of RBLR: RW1: RW2 to be 1: 9: 12, indicating that the torus lies outside the BLR and that its size increases with wavelength. Furthermore, we determine the relationship between torus size and LBOL, yielding best-fit slopes of 0.413 ± 0.047 for the W1 band and 0.397 ± 0.058 for the W2 band. Both slopes are shallower than predicted by the dust radiation equilibrium model. Furthermore, our findings indicate that the torus size systematically decreases as the Eddington ratio increases, a trend that can be explained by the self-shadowing effects of slim disks.

Keywords: Active galactic nuclei
JWST and ALMA Joint Analysis with [O II] λλ3726, 3729, [O III] λ4363, [O III] 88 μm, and [O III] 52 μm: Multizone Evolution of Electron Densities at z ∼ 0─14 and its Impact on Metallicity Measurements. We present a JWST and Atacama Large Millimeter/submillimeter Array (ALMA) detailed study of the interstellar medium properties of high-redshift galaxies. Our JWST/NIRSpec integral field unit spectroscopy targeting three galaxies at z = 6─7 detects key rest-frame optical emission lines, allowing us to derive [O II] λλ3726, 3729─based electron densities of ne,optical ∼ 1000 cm−3 on average and [O III] λ4363─based metallicities of  12+log(O/H)=8.0-8.2  in two galaxies. New ALMA Band 9 and 10 observations detect the [O III] 52 μm line in one galaxy but do not in the others, resulting in far-infrared (FIR)-based densities of ne,FIR ≲ 500 cm−3 from the [O III] 52 μm/[O III] 88 μm ratio, systematically lower than the optical [O II]-based measurements. These low FIR-based densities are comparable to those at both z ∼ 0 and z &gt; 6 in the literature, including JADES-GS-z14-0 at z = 14.18, suggesting little evolution up to z ∼ 14, in contrast to the increasing trend of optical-based densities with redshift. By conducting a JWST and ALMA joint analysis using emission lines detected with both telescopes, we find that the observed FIR [O III] 52 and 88 μm luminosities are too high to be explained by the optical-based densities at which they would be significantly collisionally de-excited. Instead, a two-zone model with distinct high- and low-density regions is required to reproduce all observed lines, indicating that FIR [O III] emission arises predominantly from low-density gas, while the optical [O III] and [O II] lines trace both regions. We further demonstrate that the direct-Te method can sometimes significantly underestimate metallicities up to 0.8 dex due to the presence of the low-density gas not fully traced by optical lines alone, highlighting the importance of combining optical and FIR lines to accurately determine gas-phase metallicities in the early Universe.

Keywords: Galaxy formation, Galaxy evolution, High-redshift galaxy clusters
Warped Disk Galaxies. II. From the Cosmic Web to the Galactic Warp. Galactic warps are common in disk galaxies. While often attributed to galaxy─galaxy tides, a nonspherical dark matter halo has also been proposed as a driver of disk warping. We investigate links among warp morphology, satellite distribution, and large-scale structure using the Sloan Digital Sky Survey catalog of warped disks compiled by W.-B. G. Zee et al. Warps are classified into 244 S- and 127 U-types, hosting 1373 and 740 satellites, respectively, and are compared to an unwarped control matched in stellar mass, redshift, and local density. As an indirect, population-level proxy for the host halo's shape and orientation, we analyze the stacked spatial distribution of satellites. Warped hosts show a significant anisotropy: an excess at 45° &lt; ϕ &lt; 90° (measured from the host major axis), peaking at P(ϕ) ≃ 0.003, versus nearly isotropic controls. Satellites of S-type warps preferentially align with the nearest cosmic filament, whereas those of U-type warps are more often perpendicular. The incidence of warps increases toward filaments (rfila &lt; 4 Mpc h−1), while the number of satellites around warped hosts remains approximately constant with filament distance, indicating a direct influence of the large-scale environment. We discuss possible links between galactic warps and the cosmic web, including anisotropic tidal fields and differences in evolutionary stage.

Keywords: Galaxy dark matter halos, Galaxy interactions, Galaxy evolution, Disk galaxies