Sazuna/UAT_keywords huggingface dataset:
The Velocity Dispersion Function for Quiescent Galaxies in Massive Clusters from IllustrisTNG. We derive the central stellar velocity dispersion function (VDF) for quiescent galaxies in 280 massive clusters with  log(M200/M⊙)&gt;14  in IllustrisTNG300. The VDF is an independent tracer of the dark matter mass distribution of subhalos in galaxy clusters. Based on the IllustrisTNG cluster catalog, we select quiescent member subhalos with a specific star formation rate &lt;2 × 10‑11 yr‑1 and stellar mass  log(M*/M⊙)&gt;9 . We then simulate fiber spectroscopy to measure the stellar velocity dispersion of the simulated galaxies; we compute the line-of-sight velocity dispersions of star particles within a cylindrical volume that penetrates the core of each subhalo. We construct the VDFs for quiescent subhalos within R 200. The simulated cluster VDF exceeds the simulated field VDF for  logσ*&gt;2.2 , indicating the preferential formation of large velocity dispersion galaxies in dense environments. The excess is similar in simulations and in the observations. We also compare the simulated VDF for the three most massive clusters with  log(M200/M⊙)&gt;15  with the observed VDF for the two most massive clusters in the local Universe, Coma and A2029. Intriguingly, the simulated VDFs are significantly lower for  logσ*&gt;2.0 . This discrepancy results from (1) a smaller number of subhalos with  log(M*/M⊙)&gt;10  in TNG300 compared to the observed clusters, and (2) a significant offset between the observed and simulated M *–σ * relations. The consistency in the overall shape of the observed and simulated VDFs offers a unique window into galaxy and structure formation in simulations.

Keywords: Galaxy clusters, Stellar mass functions, Primordial galaxies, Early-type galaxies, Magnetohydrodynamical simulations
High-redshift Halo–Galaxy Connection via Constrained Simulations. The evolution of halos with masses around M h ≈ 1011 M ⊙ and M h ≈ 1012 M ⊙ at redshifts z &gt; 9 is examined using constrained N-body simulations. The average specific mass accretion rates,  Ṁh/Mh , exhibit minimal mass dependence and generally agree with existing literature. Individual halo accretion histories, however, vary substantially. About one-third of simulations reveal an increase in  Ṁh  around z ≈ 13. Comparing simulated halos with observed galaxies having spectroscopic redshifts, we find that for galaxies at z ≳ 9, the ratio between observed star formation rate and  Ṁh  is approximately 2%. This ratio remains consistent for the stellar-to-halo mass ratio (SHMR) but only for z ≳ 10. At z ≃ 9, the SHMR is notably lower by a factor of a few. At z ≳ 10, there is an agreement between specific star formation rates (sSFRs) and  Ṁh/Mh . However, at z ≃ 9, observed sSFRs exceed simulated values by a factor of 2. It is argued that the mildly elevated SHMR in high-z halos with M h ≈ 1011 M ⊙ can be achieved by assuming the applicability of the local Kennicutt–Schmidt law and a reduced effectiveness of stellar feedback due to deeper gravitational potential of high-z halos of a fixed mass.

Keywords: Star formation, High-redshift galaxies, Galaxies
Compression Acceleration of Protons and Heavier Ions at the Heliospheric Current Sheet. Recent observations by the Parker Solar Probe (PSP) suggest that protons and heavier ions are accelerated to high energies by magnetic reconnection at the heliospheric current sheet (HCS). By solving the energetic particle transport equation in large-scale MHD simulations, we study the compression acceleration of protons and heavier ions in the reconnecting HCS. We find that the acceleration of multispecies ions results in nonthermal power-law distributions with a spectral index consistent with the PSP observations. Our study shows that the high-energy cutoff of protons can reach  Emax∼0.1 –1 MeV depending on the particle diffusion coefficients. We also study how the high-energy cutoff of different ion species scales with the charge-to-mass ratio  Emax∝(Q/M)α . When determining the diffusion coefficients from the quasi-linear theory with a Kolmogorov magnetic power spectrum, we find that α ∼ 0.4, which is somewhat smaller than α ∼ 0.7 observed by PSP.

Keywords: Interplanetary particle acceleration, Solar magnetic reconnection, Heliosphere
Galaxy Assembly Bias in the Stellar-to-halo Mass Relation for Red Central Galaxies from SDSS. We report evidence of galaxy assembly bias—the correlation between galaxy properties and biased secondary halo properties at fixed halo mass (M H)—in the stellar-to-halo mass relation for red central galaxies from the Sloan Digital Sky Survey. In the M H = 1011.5–1013.5 h ‑1 M ⊙ range, central galaxy stellar mass (M *) is correlated with the number density of galaxies within 10 h ‑1 Mpc (δ 10), a common proxy for halo formation time. This galaxy assembly bias signal is also present when M H, M *, and δ 10 are substituted with group luminosity, galaxy luminosity, and metrics of the large-scale density field. To associate differences in δ 10 with variations in halo formation time, we fitted a model that accounts for (1) errors in the M H measured by the J. L. Tinker group catalog and (2) the level of correlation between halo formation time and M * at fixed M H. Fitting of this model yields that (1) errors in M H are ∼0.15 dex and (2) halo formation time and M * are strongly correlated (Spearman's rank correlation coefficient ∼0.85). At fixed M H, variations of ∼0.4 dex in M * are associated with ∼1–3 Gyr variations in halo formation time and galaxy formation time (from stellar population fitting). These results are indicative that halo properties other than M H can impact central galaxy assembly.

Keywords: Galaxy dark matter halos, Galaxies, Large-scale structure of the universe, Observational cosmology, Extragalactic astronomy, Dark matter, Early-type galaxies
Where Have All the Sulfur Atoms Gone? Polycyclic Aromatic Hydrocarbon as a Possible Sink for the Missing Sulfur in the Interstellar Medium. I. The C–S Band Strengths. Despite its biogenic and astrochemical importance, sulfur (S), the 10th most abundant element in the interstellar medium (ISM) with a total abundance of S/H ≈ 2.2 × 10‑5, largely remains undetected in molecular clouds. Even in the diffuse ISM where S was previously often believed to be fully in the gas phase, in recent years, observational evidence has suggested that S may also be appreciably depleted from the gas. What might be the dominant S reservoir in the ISM remains unknown. Solid sulfides like MgS, FeS, and SiS2 are excluded as major S reservoirs due to the nondetection of their expected infrared spectral bands in the ISM. In this work, we explore the potential role of sulfurated polycyclic aromatic hydrocarbon (PAH) molecules—PAHs with sulfur heterocycles (PASHs)—as a sink for the missing S. Utilizing density function theory, we compute the vibrational spectra of 18 representative PASH molecules. It is found that these molecules exhibit a prominent C–S stretching band at ∼10 μm and two relatively weak C–S deformation bands at 15 and 25 μm that are not mixed with the nominal PAH bands at 6.2, 7.7, 8.6, 11.3, and 12.7 μm. If several parts per million of S (relative to H) are locked up in PAHs, the 10 μm C–S band would be detectable by Spitzer and the James Webb Space Telescope (JWST). To quantitatively explore the amount of S/H depleted in PASHs, a detailed comparison of the infrared emission spectra of PASHs with the Spitzer and JWST observations is needed.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Interstellar medium, Astrochemistry
TESS Asteroseismology of β Hydri: A Subgiant with a Born-again Dynamo. The solar-type subgiant β Hyi has long been studied as an old analog of the Sun. Although the rotation period has never been measured directly, it was estimated to be near 27 days. As a Southern Hemisphere target, it was not monitored by long-term stellar activity surveys, but archival International Ultraviolet Explorer data revealed a 12 yr activity cycle. Previous ground-based asteroseismology suggested that the star is slightly more massive and substantially larger and older than the Sun, so the similarity of both the rotation rate and the activity cycle period to solar values is perplexing. We use two months of precise time-series photometry from the Transiting Exoplanet Survey Satellite to detect solar-like oscillations in β Hyi and determine the fundamental stellar properties from asteroseismic modeling. We also obtain a direct measurement of the rotation period, which was previously estimated from an ultraviolet activity─rotation relation. We then use rotational evolution modeling to predict the rotation period expected from either standard spin-down or weakened magnetic braking (WMB). We conclude that the rotation period of β Hyi is consistent with WMB and that changes in stellar structure on the subgiant branch can reinvigorate the large-scale dynamo and briefly sustain magnetic activity cycles. Our results support the existence of a "born-again" dynamo in evolved subgiants—previously suggested to explain the cycle in 94 Aqr Aa—which can best be understood within the WMB scenario.

Keywords: Stellar oscillations, Stellar rotation, Stellar evolution, Stellar activity
Using the Cartwheel CME to Predict Off-limb Observations of CMEs for New and Upcoming UV and EUV Spectrometers. Coronal mass ejections (CMEs) expel multithermal, magnetized plasma from the Sun, and when directed toward Earth, can cause extensive damage to space and ground-based electronics. To better understand the triggering, acceleration, and evolution of CMEs, it is critical to study CME plasma properties close to the Sun. High-resolution ultraviolet and extreme ultraviolet (UV-EUV) spectroscopy can give the most detailed plasma diagnostics of CMEs in the low solar corona. Unfortunately, very few spectrally resolved observations of CMEs in the low solar corona exist. However, with the recent launch of the Spectral Imaging of the Coronal Environment on board Solar Orbiter and the upcoming missions, including the EUV High-Throughput Solar Telescope (EUVST) on Solar-C and the Multi-slit Solar Explorer (MUSE), we will have the opportunity to obtain unprecedented, spectrally resolved CME observations. Using the only full EUV spectral observation of a CME by the Hinode/EUV Imaging Spectrometer, we predict the spectra that SPICE, EUVST, and MUSE are expected to observe during an off-limb CME eruption to investigate the diagnostic capabilities of each instrument. Finally, we provide a list of density-sensitive and temperature-sensitive ratios for CME plasma diagnostics along with the expected spectral atlas for each instrument to facilitate observing sequence planning.

Keywords: Spectrometers, Solar coronal mass ejections, Solar extreme ultraviolet emission, Solar instruments
Improved Astrophysical and Computational Oscillator Strengths for Ultraviolet P II Lines. Abundance measurements for the volatile element phosphorus are important for measuring the metallicity in interstellar and circumgalactic gas, where their accuracies are limited by uncertainties in the oscillator strengths. We report updated oscillator strength values for two resonant transitions of the dominant ion P II, the transitions at 961.041 and 963.801 Å, which have historically shown large uncertainties. Using a combination of observational measurements and highly accurate quasi-relativistic Hartree─Fock theoretical calculations, we present an updated oscillator strength of f = 0.147 ± 0.021 for the poorly constrained P II resonant transition at 961.401 Å, which arises from the ground electronic state 3s 23p 2 3P0 to the excited level 3s 23p3d 3D 1o . This result utilizes archival optical spectra obtained with the Very Large Telescope for the quasar PKS 0528─250, which has a damped Lyα absorber at z = 2.811. We calculate a theoretical f-value = 0.153 for 961.401 Å consistent with our empirically derived value, and calculate a theoretical f-value = 1.79 for 963.801 Å. We also present theoretical oscillator strengths for the P II resonant transitions at 972.779, 1124.945, 1152.818, 1301.874, and 1532.533 Å, as well as for multiple P II fine-structure and excited-level transitions. The updated f-value for the P II 961 Å transition will be useful in future studies of P abundances, especially in sight lines where the 1152 Å line is saturated.

Keywords: Metal line absorbers, Optical astronomy, Laboratory astrophysics, Atomic data, Ultraviolet astronomy
Electron Densities in H II Regions from Observation of [N II] 205 μm Fine Structure and Radio Recombination Lines. We employ observations of the 205 μm [N II] fine structure (FS) line and radio recombination line (RRL) emission to derive the electron density in 10 well-known H II regions. The combination of these two spectral lines (the RRL–FS line method) provides a sensitive probe of electron density in regions with n(e) ≥ 30 cm‑3 without requiring knowledge of the size of the ionized region. By using H54α data from the Green Bank Telescope and 205 μm data from the SOFIA Airborne Observatory, we have almost identical 18″ beamwidths, removing a significant source of error for observations of H II regions due to nonuniform density across the sources observed. The electron densities vary widely among the sources observed, from 2600 to 36,000 cm‑3, with two low-density outliers at 94 and 520 cm‑3. On average, these densities are a factor of 4 greater than the highest-resolution single-antenna data and a factor of almost 13 greater than the 182″ angular resolution single-antenna data having more sources in common. The total 1σ fractional uncertainties in n(e) are in the range 0.15–0.29. In the RRL–FS line method, the observationally determined quantity is proportional to ∫n 2(z)dz / ∫n(z)dz. For a Gaussian density distribution much more extended than its 1/e radius, this is equal to  n0/2 , where n 0 is the peak electron density. The high values of electron density found are plausibly the result of the RRL–FS line technique sampling the peak of a centrally condensed density distribution.

Keywords: H II regions
Explaining Muon Excess in Cosmic Rays Using the Gluon Condensation Model. Ultrahigh-energy cosmic rays are often characterized indirectly by analyzing the properties of secondary cosmic ray particles produced in the collisions with air nuclei. The particle number N  μ  of muon and the depth of shower maximum X max after air shower cascade are mostly studied to infer the energy and mass of the incident cosmic rays. Research has shown that there is a significant excess in the observed number of muons arriving at the ground from extensive air showers compared to the simulations using the existing cosmic ray hadronic interaction model. To explain this muon excess phenomenon, a new theoretical model, the gluon condensation model, is introduced in this paper and simulated by using the AIRES engine. We assume that the gluon condensation (GC) effect appears mainly in the first collision of the cascade, leading to a significant increase in the strangeness production, consequently, the production rate of kaons is increased, and n  K /n  π  is greater than the value of the usual hadronic interaction process. In the calculation, the model assumes that only pions and kaons are produced in the GC state. The increase of strange particle yield would mean that the energy transferred from the hadronic cascade to the electromagnetic cascade through π 0 → 2γ decay is reduced. This would in turn increase the number of muons at the ground level due to meson decays. Our model provides a new theoretical possibility to explain the muon excess puzzle.

Keywords: Particle astrophysics, Cosmic ray showers, High energy astrophysics
Exploring the Central Region of NGC 1365 in the Ultraviolet Domain. Active galactic nuclei (AGN) feedback and its impact on their host galaxies are critical to our understanding of galaxy evolution. Here, we present a combined analysis of new high resolution ultraviolet (UV) data from the Ultraviolet Imaging Telescope (UVIT) on AstroSat and archival optical spectroscopic data from the Very Large Telescope/MUSE, for the Seyfert galaxy, NGC 1365. Concentrating on the central 5 kpc region, the UVIT images in the far- and near-UV show bright star-forming knots in the circumnuclear ring as well as a faint central source. After correcting for extinction, we found the star formation rate (SFR) surface density of the circumnuclear 2 kpc ring to be similar to other starbursts, despite the presence of an AGN outflow, as seen in [O III] 5007 Å. On the other hand, we found fainter UV and thus lower SFR in the direction southeast of the AGN relative to northwest in agreement with observations at other wavelengths from JWST and Atacama Large Millimeter/submillimeter Array. The AGN outflow velocity is found to be lesser than the escape velocity, suggesting that the outflowing gas will rain back into the galaxy. The deep UV data have also revealed diffuse UV emission in the direction of the AGN outflow. By combining [O III] and UV data, we found the diffuse emission to be of AGN origin.

Keywords: Ultraviolet astronomy, Seyfert galaxies, Active galactic nuclei, AGN host galaxies
Electrostatic Waves and Electron Holes in Simulations of Low-Mach Quasi-perpendicular Shocks. Collisionless low-Mach-number shocks are abundant in astrophysical and space plasma environments, exhibiting complex wave activity and wave–particle interactions. In this paper, we present 2D Particle-in-Cell (PIC) simulations of quasi-perpendicular nonrelativistic (v sh ≈ (5500–22000) km s‑1) low-Mach-number shocks, with a specific focus on studying electrostatic waves in the shock ramp and precursor regions. In these shocks, an ion-scale oblique whistler wave creates a configuration with two hot counterstreaming electron beams, which drive unstable electron acoustic waves (EAWs) that can turn into electrostatic solitary waves (ESWs) at the late stage of their evolution. By conducting simulations with periodic boundaries, we show that the EAW properties agree with linear dispersion analysis. The characteristics of ESWs in shock simulations, including their wavelength and amplitude, depend on the shock velocity. When extrapolated to shocks with realistic velocities (v sh ≈ 300 km s‑1), the ESW wavelength is reduced to one-tenth of the electron skin depth and the ESW amplitude is anticipated to surpass that of the quasi-static electric field by more than a factor of 100. These theoretical predictions may explain a discrepancy, between PIC and satellite measurements, in the relative amplitude of high- and low-frequency electric field fluctuations.

Keywords: Shocks, Planetary bow shocks, Space plasmas, Plasma astrophysics
A Gamma-Ray Flare from TXS 1508+572: Characterizing the Jet of a z = 4.31 Blazar in the Early Universe. Blazars can be detected from very large distances due to their high luminosity. However, the detection of γ-ray emission of blazars beyond z = 3 has only been confirmed for a small number of sources. Such observations probe the growth of supermassive black holes close to the peak of star formation in the history of galaxy evolution. As a result from a continuous monitoring of a sample of 80 z &gt; 3 blazars with the Fermi Large Area Telescope (Fermi-LAT), we present the first detection of a γ-ray flare from the z = 4.31 blazar TXS 1508+572. This source showed high γ-ray activity from 2022 February to August, reaching a peak luminosity comparable to the most luminous flares ever detected with Fermi-LAT. We conducted a multiwavelength observing campaign involving XMM-Newton, the Neil Gehrels Swift Observatory, the Effelsberg 100 m radio telescope, and the Very Long Baseline Array. In addition, we make use of the monitoring programs by the Zwicky Transient Facility and the Near-Earth Object Wide-field Infrared Survey Explorer at optical and infrared wavelengths, respectively. We find that the source is particularly variable in the infrared band on daily timescales. The spectral energy distribution collected during our campaign is well described by a one-zone leptonic model, with the γ-ray flare originating from an increase of external Compton emission as a result of a fresh injection of accelerated electrons.

Keywords: High energy astrophysics, Blazars, Relativistic jets, Flat-spectrum radio quasars, Radiative processes, Gamma-ray astronomy, High-redshift galaxies
Insights into the Production of <SUP>44</SUP>Ti and Nickel Isotopes in Core-collapse Supernovae. We report nucleosynthetic results for both 44Ti and nickel isotopes for 18 three-dimensional (3D) core-collapse supernova (CCSN) simulations extended to ∼20 s after bounce. We find that many of our long-term models are able to achieve 44Ti/56Ni ratios similar to that observed in Cassiopeia A, and modern supernova models can synthesize up to 2 × 10‑4 M ⊙ of 44Ti. Neutrino-driven winds and the fact that there can be simultaneous accretion and explosion in 3D models of CCSNe play central roles in its production. We conclude that the 44Ti underproduction problem in previous CCSN models is no longer an issue. In addition, we discuss the production of both 57Ni and stable nickel/iron ratios and compare our results to observations of SN 1987A and the Crab.

Keywords: Nucleosynthesis, Core-collapse supernovae
Mock Observations: Three Different Types of Galaxy Alignment in TNG100 Simulations. In this study, galaxy samples have been generated using mock observation techniques based on the results of TNG100-1 simulations to investigate three forms of intrinsic alignment: satellite-central alignment between the orientation of the brightest group galaxies (BGG) and the spatial distribution of their satellites, radial alignment between the satellites' orientation and the direction toward their BGG, as well as direct alignment between the orientation of BGG and that of its satellites. Overall, the predictions of galaxy alignment generally align with observations, although minor discrepancies have been identified. For satellite-central alignment, the alignment strength and color-dependence trends are well replicated by the mock observations. Regarding radial alignment, the signals are weak but discernible, with no apparent color dependence. As for direct alignment, no signal is detected, nor is there any color dependence. We also investigate the alignment dependencies on halo or the BGG properties, and proximity effect. For satellite-central alignment, the predicted alignment signal shows a positive correlation with halo and BGG mass, consistent with observations and previous predictions. Similar correlations have also been observed with the BGG age and metallicity, which merit future observational analysis for confirmation. Proximity effects have been observed for all three types of alignment, with satellites closer to the BGG exhibiting stronger alignment signals. The influence of galaxy definition and shape determination on alignment studies is also analyzed. This study underscores the importance of employing mock observation techniques for a fair comparison between predictions and observations.

Keywords: Galaxy infall, Hydrodynamical simulations, Galaxy formation, Galaxy planes