Sazuna/UAT_keywords huggingface dataset:
Proton and Helium Heating by Cascading Turbulence in a Low-beta Plasma. How ions are energized and heated is a fundamental problem in the study of energy dissipation in magnetized plasmas. In particular, the heating of heavy ions (including 4He2+, 3He2+, and others) has been a constant concern for understanding the microphysics of impulsive solar flares. In this article, via two-dimensional hybrid-kinetic particle-in-cell simulations, we study the heating of helium ions (4He2+) by turbulence driven by cascading waves launched at large scales from the left-handed polarized helium ion cyclotron wave branch of a multi-ion plasma composed of electrons, protons, and helium ions. We find significant parallel (to the background magnetic field) heating for both helium ions and protons due to the formation of beams and plateaus in their velocity distribution functions along the background magnetic field. The heating of helium ions in the direction perpendicular to the magnetic field starts with a lower rate than that in the parallel direction, but overtakes the parallel heating after a few hundreds of the proton gyro-periods due to cyclotron resonances with mainly obliquely propagating waves induced by the cascade of injected helium ion cyclotron waves at large scales. There is, however, little evidence for proton heating in the perpendicular direction due to the absence of left-handed polarized cyclotron waves near the proton cyclotron frequency. Our results are useful for understanding the preferential heating of 3He and other heavy ions in the 3He-rich solar energetic particle events, in which helium ions play a crucial role as a species of background ions regulating the kinetic plasma behavior.

Keywords: Solar energetic particles, Space plasmas, Solar flares, Plasma physics
Structure and Spectroscopic Signatures of Interstellar Sodium Isocyanate Isomers. The investigation of metal-containing interstellar molecules stands as a prolific field for current astrochemical research. However, the search for many of these systems in the interstellar medium has remained inaccessible to date due to the lack of preliminary spectroscopic data. In this context, pioneering theoretical studies have inspired quantum chemists to study new appealing candidates to enable their subsequent search in space. The aim of this study is to provide high-level theoretical spectroscopic signatures of the tetratomic system [Na, N, C, O]. We have performed a thorough exploration of its potential energy surface employing different state-of-the-art quantum chemical methods and nine different species have been characterized. Moreover, we have evaluated the stability of the most stable isomers against dissociation and explored their main isomerization processes. We therefore suggest sodium isocyanate (NaNCO,1Σ) and sodium cyanate, (NaOCN, 1Σ) as the most relevant candidates for laboratory and interstellar detection. To aid in their eventual spectral search by means of rotational spectroscopy, we report a complete set of the required spectroscopic parameters including the nuclear quadrupole coupling constants, which are needed to interpret their complex hyperfine structure. NaNCO and NaOCN present exceptionally high values of the electric dipole moment (11.4 and 13.6 Debyes, respectively at the CCSD(T,rw)/aug-cc-pVTZ level), which strongly support to perform an eventual radio astronomical search. Furthermore, both isomers exhibit rather small vibrational frequencies, which indicates that these species are certainly floppy molecules.

Keywords: Computational methods, Molecular data, Interstellar medium, Astrochemistry
Active Galactic Nucleus Variability in the Age of Rubin. Over the next 10 years, the Vera C. Rubin Observatory (Rubin) will observe ~10 million active galactic nuclei (AGNs) with a regular and high cadence. During this time, the intensities of most of these AGNs will fluctuate stochastically. Here, we explore the prospects to quantify precisely these fluctuations with Rubin measurements of AGN light curves. To do so, we suppose that each light curve is described by a damped random walk with a given fluctuation amplitude and correlation time. Theoretical arguments and some current measurements suggest that the correlation timescale and fluctuation amplitude for each AGN may be correlated with other observables. We use an expected-information analysis to calculate the precision with which these parameters will be inferred from the measured light curves. We find that the measurements will be so precise as to allow the AGNs to be separated into up to ~10 different correlation-timescale bins. We then show that if the correlation time varies as some power of the luminosity, the normalization and power-law index of that relation will be determined to ${ \mathcal O }({10}^{-4} \% )$ . These results suggest that with Rubin, precisely measured variability parameters will take their place alongside spectroscopy in the detailed characterization of individual AGNs and in the study of AGN population statistics. Analogous analyses will be enabled by other time-domain projects, such as CMB-S4.

Keywords: High energy astrophysics, Optical astronomy, Astrostatistics, Active galactic nuclei, Time domain astronomy, Optical telescopes
HYPHY: Deep Generative Conditional Posterior Mapping of Hydrodynamical Physics. Generating large-volume hydrodynamical simulations for cosmological observables is a computationally demanding task necessary for next-generation observations. In this work, we construct a novel fully convolutional variational autoencoder (VAE) to synthesize hydrodynamic fields conditioned on dark matter fields from N-body simulations. After training the model on a single hydrodynamical simulation, we are able to probabilistically map new dark-matter-only simulations to corresponding full hydrodynamical outputs. By sampling over the latent space of our VAE, we can generate posterior samples and study the variance of the mapping. We find that our reconstructed field provides an accurate representation of the target hydrodynamical fields as well as reasonable variance estimates. This approach has promise for the rapid generation of mocks as well as for implementation in a full inverse model of observed data.

Keywords: Neural networks, Convolutional neural networks, Intergalactic gas, Intergalactic medium, Extragalactic astronomy
Radio Observations of Four Active Galactic Nuclei Hosting Intermediate-mass Black Hole Candidates: Studying the Outflow Activity and Evolution. Observational searches for intermediate-mass black holes (IMBHs; 102-106 M ⊙) include relatively isolated dwarf galaxies. For those that host active galactic nuclei (AGNs), the IMBH nature may be discerned through the accretion-jet activity. We present radio observations of four AGN-hosting dwarf galaxies, which potentially harbor IMBHs. Very large array (VLA) observations indicate steep spectra (indices of -0.63 to -1.05) between 1.4 and 9 GHz. However, a comparison with the 9 GHz in-band spectral index shows a steepening for GH047 and GH158 (implying older/relic emission) and flattening for GH106 and GH163 (implying recent activity). Overlapping emission regions in the VLA 1.4 GHz and our very long baseline array (VLBA) 1.5 GHz observations, and possibly symmetric pc-scale extensions, are consistent with recent activity in the latter two. Using the compact VLBA radio luminosity, X-ray luminosity (probing the accretion activity), and the black hole masses, all AGNs are found to lie on the empirical fundamental plane relation. The four AGNs are radio-quiet with relatively higher Eddington ratios (0.04-0.32) and resemble X-ray binaries during spectral state transitions that entail an outflow ejection. Furthermore, the radio to X-ray luminosity ratio $\mathrm{log}{R}_{{\rm{X}}}$ of -3.9 to -5.6 in these four sources support the scenarios that include corona mass ejection from the accretion disk and wind activity. The growth to kpc-scales likely proceeds along a similar trajectory to young AGNs and peaked spectrum sources. These complex clues can thus aid in the detection and monitoring of IMBHs in the nearby universe.

Keywords: Accretion, Intermediate-mass black holes, Very long baseline interferometry, Dwarf galaxies, Radio sources
Relation of Observable Stellar Parameters to Mass-loss Rate of AGB Stars in the LMC. Using the data set of Riebel et al. for 6889 pulsating AGB stars in the LMC, we have derived formulae for mass-loss rate as a function of luminosity and pulsation period, or luminosity and mass, in three ways, for each of five subsets of data: fundamental-mode oxygen-rich stars, first-overtone-mode oxygen-rich stars, fundamental-mode carbon stars, first-overtone-mode carbon stars, and extreme carbon stars. Using the distribution of the stars in period versus luminosity and mass versus luminosity, we are able to derive a power-law fit to the dependence of mass-loss rate on those quantities. This results in formulae that reproduce observed mass-loss rates and are in general agreement with the expectation from mass-loss models that the mass-loss rate is highly sensitive to luminosity, mass, and pulsation period. In the process of carrying out this analysis we have found radius-mass-luminosity relations and examined pulsation-mass-radius relations using published evolutionary and pulsation models. These allow us to derive mass and radius from the observed quantities luminosity and pulsation period. We also derived new mass-loss rate versus color relations.

Keywords: Evolved stars, Pulsating variable stars, Stellar pulsations, Carbon stars, Stellar mass loss, Semi-regular variable stars, Mira variable stars, Asymptotic giant branch stars, Pulsation modes, Low mass stars, Late-type giant stars, M giant stars
The Poor Old Heart of the Milky Way. Our Milky Way should host an ancient, metal-poor, and centrally concentrated stellar population, which reflects the star formation and enrichment in the few most massive progenitors that coalesced at high redshift to form the proto-Galaxy. While metal-poor stars are known to reside in the inner few kiloparsecs of our Galaxy, current data do not yet provide a comprehensive picture of such a metal-poor "heart" of the Milky Way. We use information from Gaia Data Release 3, especially the XP spectra, to construct a sample of 2 million bright (G BP &lt; 15.5 mag) giant stars within 30° of the Galactic center (GC) with robust [M/H] estimates, δ[M/H] ≲ 0.1. For ~1.25 million stars we calculate orbits from Gaia Radial Velocity Spectrometer velocities and astrometry. This sample reveals an extensive, ancient, and metal-poor population that includes ~18,000 stars with -2.7 &lt; [M/H] &lt; -1.5, representing a stellar mass of ≳5 × 107 M ⊙. The spatial distribution of these [M/H] &lt; -1.5 stars has a Gaussian extent of only ${\sigma }_{{{R}}_{{\rm{GC}}}}\sim 2.7\,\mathrm{kpc}$ around the GC, with most orbits confined to the inner Galaxy. At high orbital eccentricities, there is clear evidence for accreted halo stars in their pericentral orbit phase. Most stars show [α/Fe] enhancement and [Al/Fe]-[Mn/Fe] abundances expected for an origin in the more massive portions of the proto-Galaxy. Stars with [M/H] &lt; -2 show no net rotation, whereas those with [M/H] ~ -1 are rotation dominated. These central, metal-poor stars most likely predate the oldest disk population (τ age ≈ 12.5 Gyr), which implies that they formed at z ≳ 5, forging the proto-Milky Way.

Keywords: Galaxy formation, Milky Way formation, Gaia, Milky Way dynamics, Chemical enrichment, Metallicity
The High-ionization IR Fine Structure Lines as Bolometric Indicators of the AGN Power: Study of the Complete 12 μm AGN Sample. The high-ionization mid-IR lines, excited in the narrow-line regions of active galactic nuclei (AGN), barely affected by stellar excitation and dust extinction, trace the AGN bolometric power. We used the complete 12 μm sample of Seyfert galaxies, for which 100/116 objects have reliable 2-10 keV observations. The [Ne V] and [O IV] mid-IR lines linearly correlate with several AGN bolometric indicators (intrinsic 2-10 keV and observed 14-195 keV X-ray emission, compact nuclear 12 μm emission, [O III] λ5007 Å line emission) in terms of both flux and luminosity. No evidence of systematic differences in these correlations is found among the Seyfert populations, including types 1 and 2 and Compton-thick and Compton-thin AGN. Nevertheless, we find that a sequence of high-to-low Eddington ratios together with strong-to-weak line excitation (traced by the [O IV]/[Ne II] line ratio) encompasses from type 1 through type 2 AGN to low-ionization nuclear emission-line region galaxies, showing intrinsic differences in these three AGN populations. A positive correlation between the black hole accretion rate (BHAR) and the star formation rate (SFR) is found, but no correlation between the specific SFR and the ratio BHAR/M BH, simply reflecting the fact that the more massive a galaxy is, the more it is forming stars and feeding its central black hole. The JWST, just beginning operations, will allow large samples of AGN to be observed in these lines in the nearby universe (z &lt; 0.9).

Keywords: AGN host galaxies, Starburst galaxies, Infrared spectroscopy, Active galaxies, Seyfert galaxies, X-ray active galactic nuclei, Infrared galaxies, X-ray observatories
A Molecular Gas Ring Hidden in the Sombrero Galaxy. We present Herschel, ALMA, and MUSE observations of the molecular ring of Messier 104, also known as the Sombrero galaxy. These previously unpublished archival data shed new light on the content of the interstellar medium of M104. In particular, molecular hydrogen measured by CO emission and dust measured by far-infrared light are uniformly distributed along the ring. The ionized gas revealed by Hα and [C II] emission is distributed in knots along the ring. Despite being classified as an SAa galaxy, M104 displays features typical of early-type galaxies. We therefore compared its [C II] and dust emission to a sample of early-type galaxies observed with Herschel and SOFIA. The [C II]/FIR ratio of M104 is much lower than that of typical star-forming galaxies and is instead much more similar to that of early-type galaxies. By classifying regions using optical emission line diagnostics, we also find that regions classified as H II lie closer to star-forming galaxies in the [C II]/FIR diagram than those classified as low-ionization emission regions. The good match between [C II] and Hα emission, in conjunction with the lack of correlation between CO emission and star formation, suggests that there is very limited active star formation along the ring and that most of the [C II] emission is from ionized and neutral atomic gas rather than molecular gas. From the total intensity of the CO line, we estimate a molecular hydrogen mass of 0.9 × 109 M ☉, a value intermediate between those of early-type galaxies and the content of the molecular ring of our galaxy.

Keywords: Molecular gas, Infrared galaxies, Interstellar medium, Galaxy environments
Conditional H I Mass Functions and the H I-to-halo Mass Relation in the Local Universe. We present a new H I mass estimator that relates ${\mathrm{log}}_{10}$ (M HI/M *) to a linear combination of four galaxy properties: stellar surface mass density, color index u - r, stellar mass, and concentration index, with the scatter of individual galaxies around the mean H I mass modeled with a Gaussian distribution function. We calibrate the estimator using the xGASS sample, including both H I detection and nondetection, and constrain the model parameters through Bayesian inferences. Tests with mock catalogs demonstrate that our estimator provides unbiased H I masses for optical samples like SDSS. We apply our estimator to the SDSS spectroscopic sample to estimate the H I mass function (HIMF) of local galaxies, as well as the conditional H I mass function in galaxy groups and the H I-halo mass relation. Our HIMF agrees with the ALFALFA measurements at M HI ≳ 5 × 109 M ⊙, but with higher amplitude and a steeper slope at lower masses. We show that this discrepancy is caused primarily by the cosmic variance, which is corrected for the SDSS sample but not for ALFALFA. The total CHIMFs for all halo masses can be described by a single Schechter function, while those of central galaxies show a double-Gaussian profile. The total H I mass in a group increases monotonically with halo mass, but for central galaxies, the H I mass shows weak dependence on halo mass when M h ≳ 1012 M ☉. The observed H I-halo mass relation is not reproduced by current hydrodynamic simulations and semianalytic models of galaxy formation.

Keywords: Galaxy dark matter halos, Cold dark matter, Neutral hydrogen clouds, Interstellar clouds, Cold neutral medium
SPYGLASS. II. The Multigenerational and Multiorigin Star Formation History of Cepheus Far North. Young stellar populations provide a record of past star formation, and by establishing their members' dynamics and ages, it is possible to reconstruct the full history of star formation events. Gaia has greatly expanded the number of accessible stellar populations, with one of the most notable recently discovered associations being Cepheus Far North (CFN), a population containing hundreds of members spanning over 100 pc. With its proximity (d ≲ 200 pc), apparent substructure, and relatively small population, CFN represents a manageable population to study in depth, with enough evidence of internal complexity to produce a compelling star formation story. Using Gaia astrometry and photometry combined with additional spectroscopic observations, we identify over 500 candidate CFN members spread across seven subgroups. Combining ages from isochrones, asteroseismology, dynamics, and lithium depletion, we produce well-constrained ages for all seven subgroups, revealing a largely continuous 10 Myr star formation history in the association. By tracing back the present-day populations to the time of their formation, we identify two spatially and dynamically distinct nodes in which stars form, one associated with β Cephei, which shows mostly co-spatial formation, and one associated with EE Draconis with a more dispersed star formation history. This detailed view of star formation demonstrates the complexity of the star formation process, even in the smallest of regions.

Keywords: Pre-main sequence stars, Star formation, Stellar ages, Stellar associations
Spitzer/IRS Full Spectral Modeling to Characterize Mineralogical Properties of Silicate Dust in Heavily Obscured AGNs. Mid-infrared silicate dust bands observed in heavily obscured active galactic nuclei (AGNs) include information on the mineralogical properties of silicate dust. We aim to investigate the mineralogical picture of the circumnuclear region of heavily obscured AGNs to reveal obscured AGN activities through the picture. In our previous study, we investigated the properties of silicate dust in heavily obscured AGNs, focusing on the mineralogical composition and the crystallinity with Spitzer/IRS 5.3-12 μm spectra. In this study, we model the full-range Spitzer/IRS 5-30 μm spectra of 98 heavily obscured AGNs using a one-dimensional radiative transfer calculation with four dust species in order to evaluate wider ranges of the properties of silicate dust more reliably. Comparing fitting results between four dust models with different sizes and porosities, 95 out of the 98 galaxies prefer a porous silicate dust model without micron-sized large grains. The pyroxene mass fraction and the crystallinity are overall consistent with-but significantly different from-the previous results for the individual galaxies. The pyroxene-poor composition, small dust size, and high porosity are similar to newly formed dust around mass-loss stars as seen in our Galaxy, which presumably originates from the recent circumnuclear starburst activity. The high crystallinity on average suggests dust processing induced by AGN activities.

Keywords: Astrophysical dust processes, Active galactic nuclei, Infrared galaxies
The JCMT BISTRO Survey: A Spiral Magnetic Field in a Hub-filament Structure, Monoceros R2. We present and analyze observations of polarized dust emission at 850 μm toward the central 1 × 1 pc hub-filament structure of Monoceros R2 (Mon R2). The data are obtained with SCUBA-2/POL-2 on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields in Star-forming Region Observations survey. The orientations of the magnetic field follow the spiral structure of Mon R2, which are well described by an axisymmetric magnetic field model. We estimate the turbulent component of the magnetic field using the angle difference between our observations and the best-fit model of the underlying large-scale mean magnetic field. This estimate is used to calculate the magnetic field strength using the Davis-Chandrasekhar-Fermi method, for which we also obtain the distribution of volume density and velocity dispersion using a column density map derived from Herschel data and the C18O (J = 3 - 2) data taken with HARP on the JCMT, respectively. We make maps of magnetic field strengths and mass-to-flux ratios, finding that magnetic field strengths vary from 0.02 to 3.64 mG with a mean value of 1.0 ± 0.06 mG, and the mean critical mass-to-flux ratio is 0.47 ± 0.02. Additionally, the mean Alfvén Mach number is 0.35 ± 0.01. This suggests that, in Mon R2, the magnetic fields provide resistance against large-scale gravitational collapse, and the magnetic pressure exceeds the turbulent pressure. We also investigate the properties of each filament in Mon R2. Most of the filaments are aligned along the magnetic field direction and are magnetically subcritical.

Keywords: Molecular clouds, Polarimetry, Star formation, Submillimeter astronomy, Magnetic fields
The Origin of High-energy Emission in the Young Radio Source PKS 1718-649. We present a model for the broadband radio-to-γ-ray spectral energy distribution of the compact radio source PKS 1718-649. Because of its young age (≃100 yr) and proximity (z = 0.014), PKS 1718-649 offers a unique opportunity to study the nuclear conditions and the jet/host galaxy feedback process at the time of the initial radio jet expansion. PKS 1718-649 is one of a handful of young radio jets with γ-ray emission that has been confirmed by the Fermi/LAT detector. We show that in PKS1718-649 this γ-ray emission can be successfully explained by Inverse Compton scattering of the UV photons, presumably from an accretion flow, off nonthermal electrons in the expanding radio lobes. The origin of the X-ray emission in PKS 1718-649 is more elusive. While Inverse Compton scattering of the IR photons emitted by a cold gas in the vicinity of the expanding radio lobes contributes significantly to the X-ray luminosity, the data require an additional source of X-rays, e.g., a weak X-ray corona or a radiatively inefficient accretion flow, as expected from a LINER-type nucleus, such as that of PKS 1718-649. We find that the jet in PKS 1718-649 has low power, L  j  ≃ 2 × 1042 erg s-1, and expands in an environment with density n 0 ≃ 3-20 cm-3. The inferred mass accretion rate and gas mass reservoir within 50-100 pc of the galactic center are consistent with estimates from the literature obtained by tracing molecular gas in the innermost region of the host galaxy with SINFONI and the Atacama Large Millimeter/submillimeter Array.

Keywords: Accretion, Radio jets, Extragalactic radio sources, Active galaxies, Radio lobes, Non-thermal radiation sources, X-ray active galactic nuclei, Galaxy evolution, Gamma-rays