Sazuna/UAT_keywords huggingface dataset:
Mapping the Star Formation and H I Gas Properties of Galaxies along Large-scale Structures around the Virgo Cluster. We investigate the star formation and neutral atomic hydrogen (H I) gas properties of galaxies along three large-scale filaments and two galaxy groups in the wide field around the Virgo cluster. Our goal is to understand how galaxies are processed in low-density environments before falling into high-density regions. Combining the spatial distribution of galaxies with multiwavelength colors such as W3 ‑ W1, NUV ‑ r, and g ‑ r, we find a predominance of blue galaxies across the structures, indicating normal-to-enhanced star formation, similar to that of isolated galaxies. However, one filament and one group show a significant number of red galaxies (32% and 20%, respectively), suggesting that star formation has been suppressed in low-density environments before reaching high-density regions. Intriguingly, these red galaxies span a wide range of stellar masses, and the presence of red dwarfs support that not only mass but also environment plays an important role in the quenching of star formation in cluster outskirts. One particular filament, potentially connected to Virgo, already has a group of red populations outside Virgo's R200, making these galaxies good candidates for being "preprocessed" before entering the Virgo cluster. In addition, several galaxies in the filaments and groups possess relatively low H I gas contents, similar to cluster galaxies. However, the overall fraction of H I-deficient galaxies is not as significantly high as the fraction of red galaxies in these structures. This suggests that H I gas properties are less influenced by the environment than star formation properties in low-density regions, possibly due to gas replenishment through accretion.

Keywords: Interstellar atomic gas, Galaxy environments, Star formation, Cosmic web, Galaxy groups, Galaxy evolution
Red Supergiant Problem Viewed from the Nebular Phase Spectroscopy of Type II Supernovae. The red supergiant (RSG) problem refers to the observed dearth of luminous RSGs identified as progenitors of Type II supernovae (SNe II) in pre-SN imaging. Understanding this phenomenon is essential for studying pre-SN mass loss and the explodability of core-collapse SNe. In this work, we reassess the RSG problem using late-phase spectroscopy of a sample of 50 SNe II. The [O I] λλ6300,6363 emission in the spectra is employed to infer the zero-age main-sequence (ZAMS) mass distribution of the progenitors, which is then transformed into a luminosity distribution via an observation-calibrated mass–luminosity relation. The resulting luminosity distribution reveals an upper cutoff at  logL/L⊙=5.21‑0.07+0.09 dex, and the RSG problem is statistically significant at the 2σ–3σ level. Assuming single RSG progenitors that follow the mass–luminosity relation of KEPLER models, this luminosity cutoff corresponds to an upper ZAMS mass limit of  20.63‑1.64+2.42M⊙ . Comparisons with independent measurements, including pre-SN imaging and plateau-phase light curve modeling, consistently yield an upper ZAMS mass limit below ∼25 M⊙, with a significance level of 1σ–3σ. While each individual method provides only marginal significance, the consistency across multiple methodologies suggests that the lack of luminous RSG progenitors may reflect a genuine physical problem. Finally, we discuss several scenarios to account for this issue should it be confirmed as a true manifestation of stellar physics.

Keywords: Red supergiant stars, Core-collapse supernovae
Resonant Absorption and Fluctuations via Hybrid Simulations on Coronal Loops. I. Plasma Multifluid Description. We investigate the resonant absorption process of a combination of left- and right-hand polarized waves (with a fixed perturbation amplitude) in a plasma slab with linearly inhomogeneous particle densities. Different thicknesses of the layers and angles of the background magnetic field to the plane of the slab, representing the degree of magnetization of the slab, are studied via 2D‑3V PIC-hybrid simulations with a fixed perturbation amplitude. We identify the process of resonant absorption of the large-scale mode in the inhomogeneous layers and compare the damping rate of the transverse oscillations with single-fluid, linear MHD estimations. By following the spectral densities of the magnetic field fluctuations, it is found that kinetic scales are achieved in most of the simulated cases, particularly in the case of thinner inhomogeneous layers and in cases where the plasma slab is not weakly magnetized. In particular, the scales of the fluctuations can reach the proton inertial length. The small-scale fluctuations are identified as quasi-perpendicular oscillations localized within the inhomogeneous layers, and their properties in the spectral representation agree with theoretical properties of kinetic Alfvén waves predicted by kinetic and Hall-MHD theories.

Keywords: Solar atmosphere, Magnetohydrodynamics, Plasma physics, Solar physics, Alfven waves
A Persistent Disk Wind and Variable Jet Outflow in the Neutron-star Low-mass X-Ray Binary GX 13+1. In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multiwavelength campaign (using the Very Large Array (VLA), Chandra/High Energy Transmission Grating Spectrometer (HETG), and NICER) on the near-Eddington neutron-star Z-source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations—contrary to typical behavior in Z sources—and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.

Keywords: Low-mass x-ray binary stars, X-ray astronomy, Stellar accretion disks, Radio jets
The Roman View of Strong Gravitational Lenses. Galaxy─galaxy strong gravitational lenses can constrain dark matter models and the Lambda cold dark matter cosmological paradigm at subgalactic scales. Currently, there is a dearth of images of these rare systems with high signal-to-noise ratio (SNR) and angular resolution. The Nancy Grace Roman Space Telescope (hereafter Roman), scheduled for launch in late 2026, will play a transformative role in strong-lensing science with its planned wide-field surveys. With its remarkable 0.281 square degree field of view and diffraction-limited angular resolution of ~0 .″ 1, Roman is uniquely suited to characterizing dark matter substructure from a robust population of strong lenses. We present a yield simulation of detectable strong lenses in Roman's planned High Latitude Wide Area Survey (HLWAS). We simulate a population of galaxy─galaxy strong lenses across cosmic time with cold dark matter subhalo populations, select those detectable in the HLWAS, and generate simulated images accounting for realistic Wide Field Instrument detector effects. For a fiducial case of single 146 s exposures, we predict around 160,000 detectable strong lenses in the HLWAS, of which about 500 will have sufficient SNR to be amenable to detailed substructure characterization. We investigate the effect of variation of the point-spread function across Roman's field of view on detecting individual subhalos and the suppression of the subhalo mass function at low masses. Our simulation products are available to support strong-lens science with Roman, such as training neural networks and validating dark matter substructure analysis pipelines.

Keywords: Strong gravitational lensing, Dark matter distribution, Dark matter
Electrostatic Field Formed by Charge Separation in Antiparallel Magnetic Reconnection. The Hall effect resulting from the decoupled motions between ions and electrons is a critical factor in modeling collisionless magnetic reconnection. It leads to the production of charge separation in the reconnection plane, generating the electrostatic field with components perpendicular and parallel to the magnetic field. In this paper, using a 2.5-dimensional particle-in-cell simulation, we investigate the formation of the charge separation in antiparallel magnetic reconnection. The charge separation is formed in three regions: the electron inflow region and the dipolarization front (DF) region both exhibit a positive charge density, while the electron outflow region exhibits a negative charge density. These charge separations generate the Hall electric field perpendicular to the magnetic field and the parallel electrostatic field. We quantitatively analyze the effects of the magnetic flux tube's geometric dimensions and the parallel electron flux on the formation of charge separation. In the electron inflow region, the parallel electron flux from regions with smaller cross sections to regions with larger cross sections reduces electron density, generating a positive charge density near the separatrix. In contrast, within the outflow region, the parallel electron flux from regions with larger cross sections to regions with smaller cross sections increases electron density, generating a negative charge density near the separatrix. Besides, we attribute the charge separation in the DF region mainly to the acceleration of electrons, which generates a sharply varying parallel electron flux. This drives a net outflow of electrons and establishes an accumulation of positive charge.

Keywords: Space plasmas, Planetary magnetospheres, Plasma physics
Li-rich Unevolved Stars from LAMOST-MRS. Based on the spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope medium-resolution spectroscopic survey, we select a sample of 88 Li-rich unevolved star candidates. We redetermine their photospheric lithium abundances, A(Li), through the spectral synthesis method, and take the nonlocal thermodynamic equilibrium (NLTE) into account. It is found that there are 62 stars with A(Li) ranging from 3.33 to 4.59 dex. Among them, 23 stars are young stellar objects. There are 33 super Li-rich unevolved stars with A(Li) higher than 3.8 dex, and 24 of them are newly identified. The NLTE corrections for A(Li) are negative, with a maximum value of around 0.5 dex. Our results suggest that the mechanisms such as mass transfer in binary systems, accretion of circumstellar materials, and diffusion processes may contribute to lithium enrichment in their respective samples.

Keywords: Binary stars, Stellar abundances, Circumstellar matter, Young stellar objects, Lithium stars, Overabundances, Chemically peculiar stars
Morphological Feature Distances among the Spectral Types of SDSS Galaxies. This study investigates the morphological feature distances among various spectral types of galaxies from the Sloan Digital Sky Survey, including strong and weak active galactic nuclei (AGN), quasi-stellar objects (QSOs), quiescent, and star-forming galaxies. We evaluated the clustering and relative distances of these spectral types in the multidimensional morphological feature space. The results indicate that AGN and QSOs are more closely associated with quiescent galaxies than with star-forming ones, indicating a potential regulation of star formation by AGN activity. Furthermore, the analysis underlines the role of AGN feedback in the dwarf regime having ∼10%–50% closer distances from AGN types to the quiescent type than to the star-forming type in the dwarf regime ‑18 &gt; Mr &gt; ‑20, compared to &lt;15% closer in the massive regime Mr &lt; ‑21. The continuous probability analysis of spectral types being Hubble types upholds the distance analysis results having a range of the probability distribution of AGN types similar to the quiescent type, especially in dwarf galaxies.

Keywords: AGN host galaxies, Galaxy quenching, Dwarf galaxies, Galaxy classification systems
FAST Reveals the Extended H I Halo and Accretion Signatures of NGC 2683. We present the results of our recent H I observations conducted on the edge-on galaxy NGC 2683 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In comparison to previous observations made by the Very Large Array (VLA), FAST has detected a more extensive distribution of H I. Particularly noteworthy is that the detections made by FAST extend approximately 4 times farther than those of the VLA in the vertical direction from the galactic plane. The total H I flux measured for NGC 2683 amounts to FH I = 112.1 Jy km s‑1 (equivalent to a total H I mass of MH I = 2.32 × 109 M⊙), which is slightly higher than that detected by VLA. FAST has also identified three dwarf galaxies in close proximity to NGC 2683, namely KK 69, NGC 2683dw1, and NGC 2683dw3? (hereafter dw3?). dw3? is situated within the extended H I distribution of NGC 2683 in projection and lies near the tail of KK 69 extending toward NGC 2683. These observations suggest that dw3? is likely a result of the accretion process from NGC 2683 to KK 69. Furthermore, FAST has detected three high-velocity clouds, with complex B potentially undergoing accretion with NGC 2683. Based on the model from B. Vollmer et al. and incorporating the H I halo component, we found that the model with the added H I halo aligns more closely with our FAST observations in NGC 2683. The estimated mass of this H I halo is 3 × 108 M⊙, constituting approximately 13% of the total H I mass of the galaxy. We suggest that the origination of this H I halo is more likely attributed to external gas accretion.

Keywords: Interstellar medium, Galaxy interactions, Galaxy accretion
Recurrent Eruptions from the Emergence of a Toroidal Flux Tube. Solar eruptive behavior is often modeled with magnetohydrodynamic simulations of magnetic flux emergence. The usual geometry considered is that of a horizontal cylindrical magnetic flux tube. An alternative is the toroidal tube geometry, which has some advantages over the cylindrical one, namely, that the emerging bipolar pair of sunspots does not drift apart indefinitely. In addition to the toroidal tube, we include an oblique, ambient field in the simulation, which leads to the production of increased activity from the interaction of ambient and emerging fields. Letting the simulation run for a long time reveals that six eruptive jets take place after an initial reconnection jet. In an attempt to better understand the eruptive activity, we examine the evolution of free energy and relative helicity of the coronal volume, as well as the magnetic tension forces acting on the magnetic system. We find that all quantities decrease in magnitude during the eruptive jets and rebuild afterwards. This recurrent activity continues even after flux emergence ceases and stops once the examined quantities saturate to nearly constant values.

Keywords: Magnetohydrodynamical simulations
Unveiling Physical Conditions and Star Formation Processes in the G47 Filamentary Cloud. We present a multiwavelength study of the filamentary cloud G47 (d ∼ 4.44 kpc), which hosts the mid-infrared bubbles N98, B1, and B2. The SMGPS 1.3 GHz continuum map detects ionized emission toward all the bubbles, marking the first detection of ionized emission toward the B2 bubble. Analysis of the unWISE 12.0 μm image, the Spitzer 8.0 μm image, and the Herschel column density and temperature maps reveals two previously unreported hub–filament system candidates associated with the H II regions B2 and N98, which are powered by massive OB stars. This indirectly favors the applicability of a global nonisotropic collapse scenario for massive star formation in N98 and B2. The position–position–velocity diagram of FUGIN 13CO (1–0) shows significant velocity variations from 61 to 53 km s‑1 toward areas between B2 and N98, where the magnetic field morphology exhibits significant curvature and high velocity dispersion (i.e., 2.3–3.1 km s‑1) is observed. This may be explained by the expansion of the H II regions B2 and N98. The energy budget of the cloud, estimated using SOFIA/HAWC+ and molecular line data, suggests that the magnetic field dominates over turbulence and gravity in G47. Furthermore, the radial column density and velocity profiles of G47 display signatures of converging flows in a sheet-like structure. The relative orientations between the magnetic field and local gravity suggest that G47 may undergo gravitational contraction along the magnetic field lines once it becomes magnetically supercritical.

Keywords: Star forming regions, Interstellar dust extinction, Star formation, Interstellar clouds, H II regions
Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15 yr Data Set. Galaxy mergers, each hosting a supermassive black hole (SMBH), are thought to form SMBH binaries. Motivated by recent observations from the East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) showing periodic behavior in the M87 jet, a precession of about 11 yr and a transverse oscillation of about 0.9 yr, we constrain the mass of a hypothetical secondary black hole orbiting the primary SMBH in M87. To constrain the mass ratio between the primary SMBH (M1) and the secondary black hole (M2) defined as q ≡ M2/M1 ≤ 1, and the length of the semimajor axis of the binary system (a), we impose the following three constraints: (i) the lower limit of a, below which the SMBH binary is expected to merge; (ii) the strain amplitude of the gravitational-wave background at nanohertz frequencies shown in the NANOGrav 15 yr data set; and (iii) a finite length of the semimajor axis of M1, which can induce periodic behavior in the jet. By combining these constraints, we obtain the allowed parameter space for q and a. If either of the EAVN-detected periods (T) corresponds to the binary's orbital period, the allowed range of q is 6.9 × 10‑3 ≤ q ≤ 4.2 × 10‑2 for T ≈ 11 yr, and 3.7 × 10‑2 ≤ q ≤ 1 for T ≈ 0.9 yr. VLBI astrometric monitoring of the jet base of M87 is essential to explore the allowed parameter space for q and a.

Keywords: Supermassive black holes, Very long baseline interferometry, Gravitational wave astronomy, Active galactic nuclei, Radio interferometry
IGR J12580+0134: The Nearest Tidal Disruption Event and Its Faint Resurrection. Tidal disruption events (TDEs) are X-ray and gamma-ray radiations emerging from the tidal disintegration of a star or substellar object that passes too close to a supermassive black hole (SMBH) at the center of a galaxy. In 2010 November, a TDE designated as IGR J12580+0134 occurred in the galaxy NGC 4845, and it was traced by follow-up XMM-Newton observations in 2011 January. To identify a further TDE based on the radio outburst cycle, we requested NICER monitoring observations for nearly 1 yr beginning in 2023 March, which we studied here along with the previous XMM-Newton observations. We analyzed X-ray brightness changes using hardness analysis and principal component analysis (PCA) and conducted spectral analysis of the source continuum. The NICER observations revealed the presence of some X-ray flares during 2023 March–June that were much fainter than the TDE observed using XMM-Newton in 2011. The PCA component that mainly contributes to the X-ray outbursts during the TDE is a heavily absorbed power-law continuum emission, whereas there is a small contribution from collisionally ionized plasma in the soft excess, likely from a colliding wind or jet. Similarly, the PCA of the NICER data relates the X-ray flares to a power-law spectrum, albeit with a much lower absorbing column, and partially to soft collisional plasma. The faint X-ray flares captured by NICER could be associated with extremely weak accretion onto the SMBH resident in this galaxy and thus potentially a low-luminosity active galactic nucleus.

Keywords: Black hole physics, Tidal disruption, Active galaxies, Principal component analysis, Active galactic nuclei, X-ray sources
Dust Continuum Radiation Maps from MHD Simulations of Accretion-ejection Systems around Single and Binary Stars. We study the launching of magnetized jets from a resistive circumstellar disk within a binary system, employing a unique combination of 3D MHD jet launching simulations (PLUTO code) and post-processed 3D radiative transfer modeling (RADMC-3D code). Our findings reveal a well-defined jet originating from the inner region of the disk, extending to a larger disk area. While the model attains steady states for a single star, a binary system leads to the emergence of tidal effects such as the formation of "spiral arms" in the disk and inside the jet. Here, we have consistently implemented a time-dependent Roche potential for the gravity of the binary. As a major step forward, we further present the first 3D radiation maps of the dust continuum for the disk-jet structure. In principle, this allows us to compare MHD simulation results to observed disk-outflow features. We, therefore, present convolved images of the dust continuum emission, employing exemplary point spread functions of the MIRI instrument (5 μm band) and the Atacama Large Millimeter/submillimeter Array (320 μm band). In these bands, we identify distinguishable features of the disk-jet structure, such as "spiral arms," which we have also seen in the MHD dynamics. For gas density increased by an order of magnitude, the disk becomes optically thick at 5 μm, but remains bright at 320 μm. At this wavelength, 320 μm, enhanced structural features in the disk and the base of the wind become more pronounced and are well resolved in the convolved image.

Keywords: Magnetohydrodynamics, Binary stars, Stellar jets, Circumstellar disks, Radiative transfer simulations, Magnetohydrodynamical simulations
Increased Lyα Opacity in White Dwarf Photospheres from Transient H<SUP>‑</SUP> Resonances. The structure and emergent flux of hydrogen atmosphere white dwarfs depend on the opacity of the Lyα and Lyβ spectral lines. The opacity here is set by the strength and broadening of these lines; the latter is dictated by the far line wing, which is in the "quasi-static" limit of electron broadening, placing it in the incomplete collision regime, and describes the transient parts of electron and ion collisions. These transient stages of the collision form resonances: In the case of ions, they manifest as molecular resonances, while for electrons they are H‑ resonances, both of which can only be captured quantum-mechanically. Quantum-mechanical calculations have historically preserved only a handful of broadening terms that are most important near the center of the line. However, in the wings of the line, the previously neglected terms that describe the transient stages of the collision need to be included. This requirement arises because, in the line wings, the broadening from the 1s ground state, which is generally assumed to be extremely small compared to the broadening of the upper state, is no longer negligible within a quantum-mechanical model that takes into account exchange interactions. The inclusion of all the transient terms results in asymmetries and extra broadening. The increased broadening of Lyα increases the opacity at the energy where most of the flux leaves the star. The broader Lyα lines also impact the visible flux, raising it by an amount that exceeds previously estimated errors.

Keywords: Atomic physics, White dwarf stars, Collision physics, Atomic spectroscopy, DA stars, Stellar spectral lines