Sazuna/UAT_keywords huggingface dataset:
A New Physical Picture for Active Galactic Nuclei Lacking Optical Emission Lines. In this work, we use ~500 low-redshift (z ~ 0.1) X-ray active galactic nuclei (AGNs) observed by XMM-Newton and the Sloan Digital Sky Survey (SDSS) to investigate the prevalence and nature of AGNs that apparently lack optical emission lines ("optically dull AGNs"). Although one quarter of spectra appear absorption-line dominated in visual assessment, line extraction with robust continuum subtraction from the MPA/JHU catalog reveals usable [O III] measurements in 98% of the sample, allowing us to study [O III]-underluminous AGNs together with more typical AGNs in the context of the L [O III]-L X relation. We find that "optically dull AGNs" do not constitute a distinct population of AGNs. Instead, they are the [O III]-underluminous tail of a single, unimodal L [O III]-L X relation that has substantial scatter (0.6 dex). We find the degree to which an AGN is underluminous in [O III] correlates with the specific star formation rate or D 4000 index of the host, which are both linked to the molecular gas fraction. Thus the emerging physical picture for the large scatter seems to involve the gas content of the narrow-line region. We find no significant role for previously proposed scenarios for the presence of optically dull AGNs, such as host dilution or dust obscuration. Despite occasionally weak lines in SDSS spectra, &gt;80% of X-ray AGNs are identified as such with the Baldwin-Phillips-Terlevich diagram. More than 90% are classified as AGNs based only on [N II]/Hα, providing more complete AGN samples when [O III] or Hβ are weak. X-ray AGNs with LINER spectra obey essentially the same L [O III]-L X relation as Seyfert 2s, suggesting their line emission is produced by AGN activity.

Keywords: Active galaxies, Emission line galaxies, LINER galaxies, Seyfert galaxies, X-ray active galactic nuclei, Active galactic nuclei
On the Role of Dynamical Cooling in the Dynamics of Circumbinary Disks. Hydrodynamical interactions between binaries and circumbinary disks (CBDs) play an important role in a variety of astrophysical systems, from young stellar binaries to supermassive black hole binaries. Previous simulations of CBDs have mostly employed locally isothermal equations of state. We carry out 2D viscous hydrodynamic simulations of CBDs around equal-mass, circular binaries, treating the gas thermodynamics by thermal relaxation toward equilibrium temperature (the constant-β cooling ansatz, where β is the cooling time in units of the local Keplerian time). As an initial study, we use the grid-based code Athena++ on a polar grid, covering an extended disk outside the binary co-orbital region. We find that with a longer cooling time, the accretion variability is gradually suppressed, and the morphology of the CBD becomes more symmetric. The disk also shows evidence of hysteresis behavior depending on the initial conditions. Gas cooling also affects the rate of angular momentum transfer between the binary and the CBD, where given our adopted disk thickness and viscosity (H/r ~ 0.1 and α ~ 0.1), the binary orbit expands while undergoing accretion for most β values between 0 and 4.0 except over a narrow range of intermediate β values. The validity of using a polar grid excising the central domain is also discussed.

Keywords: Accretion, Hydrodynamical simulations, Black hole physics, Binary stars, Hydrodynamics, Circumstellar disks
The Small-scale Dynamo in a Multiphase Supernova-driven Medium. Magnetic fields grow quickly, even at early cosmological times, suggesting the action of a small-scale dynamo (SSD) in the interstellar medium (ISM) of galaxies. Many studies have focused on idealized, isotropic, homogeneous, turbulent driving of the SSD. Here we analyze more realistic simulations of supernova-driven turbulence to understand how it drives an SSD. We find that SSD growth rates are intermittently variable as a result of the evolving multiphase ISM structure. Rapid growth in the magnetic field typically occurs in hot gas, with the highest overall growth rates occurring when the fractional volume of hot gas is large. SSD growth rates correlate most strongly with vorticity and fluid Reynolds number, which also both correlate strongly with gas temperature. Rotational energy exceeds irrotational energy in all phases, but particularly in the hot phase while SSD growth is most rapid. Supernova rate does not significantly affect the ISM average kinetic energy density. Rather, higher temperatures associated with high supernova rates tend to increase SSD growth rates. SSD saturates with total magnetic energy density around 5% of equipartition to kinetic energy density, increasing slightly with magnetic Prandtl number. While magnetic energy density in the hot gas can exceed that of the other phases when SSD grows most rapidly, it saturates below 5% of equipartition with kinetic energy in the hot gas, while in the cold gas it attains 100%. Fast, intermittent growth of the magnetic field appears to be a characteristic behavior of supernova-driven, multiphase turbulence.

Keywords: Galaxy magnetic fields, Interstellar phases, Magnetohydrodynamics, Interstellar dynamics, Plasma astrophysics, Supernova remnants, Interstellar magnetic fields, Interstellar medium, Astrophysical fluid dynamics, Magnetohydrodynamical simulations
HETDEX Public Source Catalog 1: 220 K Sources Including Over 50 K Lyα Emitters from an Untargeted Wide-area Spectroscopic Survey. We present the first publicly released catalog of sources obtained from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral field spectroscopic survey designed to measure the Hubble expansion parameter and angular diameter distance at 1.88 &lt; z &lt; 3.52 by using the spatial distribution of more than a million Lyα-emitting galaxies over a total target area of 540 deg2. The catalog comes from contiguous fiber spectra coverage of 25 deg2 of sky from 2017 January through 2020 June, where object detection is performed through two complementary detection methods: one designed to search for line emission and the other a search for continuum emission. The HETDEX public release catalog is dominated by emission-line galaxies and includes 51,863 Lyα-emitting galaxy (LAE) identifications and 123,891 [O II]-emitting galaxies at z &lt; 0.5. Also included in the catalog are 37,916 stars, 5274 low-redshift (z &lt; 0.5) galaxies without emission lines, and 4976 active galactic nuclei. The catalog provides sky coordinates, redshifts, line identifications, classification information, line fluxes, [O II] and Lyα line luminosities where applicable, and spectra for all identified sources processed by the HETDEX detection pipeline. Extensive testing demonstrates that HETDEX redshifts agree to within Δz &lt; 0.02, 96.1% of the time to those in external spectroscopic catalogs. We measure the photometric counterpart fraction in deep ancillary Hyper Suprime-Cam imaging and find that only 55.5% of the LAE sample has an r-band continuum counterpart down to a limiting magnitude of r ~ 26.2 mag (AB) indicating that an LAE search of similar sensitivity to HETDEX with photometric preselection would miss nearly half of the HETDEX LAE catalog sample. Data access and details about the catalog can be found online at http://hetdex.org/. A copy of the catalogs presented in this work (Version 3.2) is available to download at Zenodo doi:10.5281/zenodo.7448504. * Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Lyman-alpha galaxies, Emission line galaxies, Redshift surveys, Catalogs
Quijote-PNG: The Information Content of the Halo Power Spectrum and Bispectrum. We investigate how much can be learnt about four types of primordial non-Gaussianity (PNG) from small-scale measurements of the halo field. Using the QUIJOTE-PNG simulations, we quantify the information content accessible with measurements of the halo power spectrum monopole and quadrupole, the matter power spectrum, the halo-matter cross spectrum, and the halo bispectrum monopole. This analysis is the first to include small, nonlinear scales, up to ${k}_{\max }=0.5\,{\rm{h}}\,{\mathrm{Mpc}}^{-1}$ , and to explore whether these scales can break degeneracies with cosmological and nuisance parameters making use of thousands of N-body simulations. We perform all the halo measurements in redshift space with a single sample comprised of all halos with mass &gt;3.2 × 1013 h -1 M ⊙. For local PNG, measurements of the scale-dependent bias effect from the power spectrum using sample variance cancellation provide significantly tighter constraints than measurements of the halo bispectrum. In this case measurements of the small scales add minimal additional constraining power. In contrast, the information on equilateral and orthogonal PNG is primarily accessible through the bispectrum. For these shapes, small-scale measurements increase the constraining power of the halo bispectrum by up to 4×, though the addition of scales beyond k ≈ 0.3 h Mpc-1 improves constraints largely through reducing degeneracies between PNG and the other parameters. These degeneracies are even more powerfully mitigated through combining power spectrum and bispectrum measurements. However, even with combined measurements and small-scale information, equilateral non-Gaussianity remains highly degenerate with σ 8 and our bias model.

Keywords: Cosmology, Non-Gaussianity, Observational cosmology, Large-scale structure of the universe
REQUIEM-2D: A Diversity of Formation Pathways in a Sample of Spatially Resolved Massive Quiescent Galaxies at z   2. REQUIEM-2D (Resolving Quiescent Magnified Galaxies with 2D Grism Spectroscopy) comprises a sample of eight massive ( ${\rm{log}}({M}_{\ast }/{M}_{\odot })\gt 10.6$ ) strongly lensed quiescent galaxies at z ~ 2. REQUIEM-2D combines the natural magnification from strong gravitational lensing with the high-spatial-resolution grism spectroscopy of the Hubble Space Telescope through a spectrophotometric fit to study spatially resolved stellar populations. We show that quiescent galaxies in the REQUIEM-2D survey have diverse formation histories with age gradients at the 1σ-3σ level, including examples of (1) a younger central region supporting outside-in formation, (2) flat age gradients that show evidence for both spatially uniform early formation and inside-out quenching, and (3) regions at a fixed radial distance having different ages (such asymmetries cannot be recovered when averaging stellar population measurements azimuthally). The typical dust attenuation curve for the REQUIEM-2D galaxies is constrained to be steeper than Calzetti's law in the UV and generally consistent with A  V  &lt; 1. Combined together and accounting for the different physical radial distances and formation timescales, we find that the REQUIEM-2D galaxies that formed earlier in the universe exhibit slow and uniform growth in their inner core, whereas the galaxies that formed later have rapid inner growth in their inner core with younger ages than the outskirts. These results challenge the currently accepted paradigm of how massive quiescent galaxies form, where the earliest galaxies are thought to form most rapidly. Significantly larger samples close to the epoch of formation with similar data quality and higher spectral resolution are required to validate this finding.

Keywords: Extragalactic astronomy, Galaxy formation, Observational astronomy
Observations of Magnetic Reconnection and Particle Acceleration Locations in Solar Coronal Jets. We present a multiwavelength analysis of two flare-related jets on 2014 November 13, using data from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), the Reuven High Energy Solar Spectroscopic Imager (RHESSI), the Hinode/X-ray Telescope (XRT), and the Interface Region Imaging Spectrograph (IRIS). Unlike most coronal jets, where hard X-ray (HXR) emissions are usually observed near the jet base, in these events HXR emissions are found at several locations, including in the corona. We carry out the first differential emission measure analysis that combines both AIA (and XRT, when available) bandpass filter data and RHESSI HXR measurements for coronal jets, and obtain self-consistent results across a wide temperature range and into nonthermal energies. In both events, hot plasma first appears at the jet base, but as the base plasma gradually cools, hot plasma also appears near the jet top. Moreover, nonthermal electrons, while only mildly energetic, are found in multiple HXR locations and contain large amounts of total energy. In particular, the energetic electrons that produce the HXR sources at the jet top are accelerated near the top location, rather than traveling from a reconnection site at the jet base. This means that there is more than one particle acceleration site in each event. Jet velocities are consistent with previous studies, including the upward and downward velocities around ~200 km s-1 and ~100 km s-1, respectively, and fast outflows of 400-700 km s-1. We also examine the energy partition in the later event, and find that the nonthermal energy in the accelerated electrons is most significant compared to the other energy forms considered. We discuss the interpretations and provide constraints on the mechanisms for coronal jet formation.

Keywords: Solar energetic particles, The Sun, Jets, Solar x-ray flares
Three-stage Collapse of the Long Gamma-Ray Burst from GRB 160625B Prompt Multiwavelength Observations. This article presents the early results of synchronous multiwavelength observations of one of the brightest gamma-ray bursts (GRBs) GRB 160625B with the detailed continuous fast optical photometry of its optical counterpart obtained by MASTER and with hard X-ray and gamma-ray emission, obtained by the Lomonosov and Konus-Wind spacecraft. The detailed photometry led us to detect the quasi-periodical emission components in the intrinsic optical emission. As a result of our analysis of synchronous multiwavelength observations, we propose a three-stage collapse scenario for this long and bright GRB. We suggest that quasiperiodic fluctuations may be associated with forced precession of a self-gravitating rapidly rotating superdense body (spinar), whose evolution is determined by a powerful magnetic field. The spinar's mass allows it to collapse into a black hole at the end of evolution.

Keywords: Neutron stars, Gamma-ray bursts, Black holes
Discovery of a New Molecular Bubble-Outflow Structure in the Taurus B18 Cloud. Star formation can produce bubbles and outflows, as a result of stellar feedback. Outflows and bubbles inject momentum and energy into the surrounding interstellar medium, and so are related to the overall energy balance of the molecular cloud. Molecular bubbles can be resolved by higher-resolution radio telescopes to quantify the effect of star formation on molecular clouds. We report here the identification of a new molecular bubble with an outflow, and a Herbig-Haro object, HH 319, located at the bubble center. Multiwavelength data have been utilized to study its spatial structure, energy injection, and dynamical timescale. This bubble has a kinetic energy of 5.8 × 1043 erg within the smallest radius of a bubble in Taurus, 0.077 pc. The bubble formed ~70,000 yr ago. According to the proper-motion velocities of protostars from Gaia EDR3, the T Tauri binary stars (FY Tau and FZ Tau) at the southwest edge of the bubble may have produced the outflow-bubble structure. This is an unusual new structure found in low- and intermediate-mass star formation regions. Only a bubble in Orion A, driven by V380 Ori, has a similar structure. The bubble-outflow structure provides additional observational evidence for the theory of stellar wind from T Tauri stars. It enhances our understanding of how stellar feedback acts on molecular clouds.

Keywords: Stellar feedback, Stellar wind bubbles, Molecular clouds, T Tauri stars, Stellar winds
Inner Habitable Zone Boundary for Eccentric Exoplanets. The climate of a planet can be strongly affected by its eccentricity due to variations in the stellar flux. There are two limits for the dependence of the inner habitable zone boundary (IHZ) on eccentricity: (1) the mean stellar flux approximation ( ${S}_{{\rm{IHZ}}}\propto \sqrt{1-{e}^{2}}$ ), in which the temperature is approximately constant throughout the orbit, and (2) the maximum stellar flux approximation (S IHZ ∝ (1 - e)2), in which the temperature adjusts instantaneously to the stellar flux. Which limit is appropriate is determined by the dimensionless parameter ${\rm{\Pi }}=\tfrac{C}{{BP}}$ , where C is the heat capacity of the planet, P is the orbital period, and $B=\tfrac{\partial {\rm{\Omega }}}{\partial {T}_{s}}$ , where Ω is the outgoing long-wave radiation and T  s  is the surface temperature. We use the Buckingham Π theorem to derive an analytical function for the IHZ in terms of eccentricity and Π. We then build a time-dependent energy balance model to resolve the surface temperature evolution and constrain our analytical result. We find that Π must be greater than about ~1 for the mean stellar flux approximation to be nearly exact and less than about ~0.01 for the maximum stellar flux approximation to be nearly exact. In addition to assuming a constant heat capacity, we also consider the effective heat capacity including latent heat (evaporation and precipitation). We find that for planets with an Earthlike ocean, the IHZ should follow the mean stellar flux limit for all eccentricities. This work will aid in the prioritization of potentially habitable exoplanets with nonzero eccentricity for follow-up characterization.

Keywords: Exoplanets, Elliptical orbits, Exoplanet astronomy, Habitable zone, Habitable planets
Constraints on Gamma-Ray Burst Models from GRB 221009A: GeV Gamma Rays versus High-energy Neutrinos. Gamma-ray bursts (GRBs) are generally believed to be efficient particle accelerators. In the presence of energetic protons in a GRB jet, interactions between these protons and the intense radiation field of the GRB are supposed to induce an electromagnetic cascade. Electrons/positrons generated in the cascade will produce an additional spectrum of a robust feature, which is in the form of a power-law distribution up to a GeV regime with an index of ≲2. We suggest that measurements of the Fermi Large Area Telescope at the GeV band can provide independent constraints on the key GRB model parameters such as the dissipation radius, the jet's bulk Lorentz factor, and the baryon loading factor. Taking GRB 221009A, the brightest GRB ever detected, as an example, we show that the constraints from GeV gamma-ray emission may be more stringent than that from the neutrino observation, providing us with deep insight into the origin of GRBs.

Keywords: Neutrino astronomy, Gamma-ray bursts, Cosmic ray sources
Photons' Scattering in Relativistic Plasma with Velocity Shear: Generation of High Energy Power-law Spectra. A high energy power law is a common feature in the spectra of many astrophysical objects. We show that the photons in an unmagnetized relativistic plasma composed of electrons and protons with a variable Lorentz factor (or a velocity shear) go through repeated scattering with electrons to gain energy. The escaped population of photons naturally produces a power-law-shaped spectrum making it a photon's analog to the conventional Fermi acceleration mechanism for charged particles. Thus, this mechanism provides a natural alternative to current explanations of high energy power-law spectra via synchrotron or thermal Comptonization. The model is applicable to any relativistic plasma beam with an arbitrary Lorentz factor profile. We implement the theory to the gamma-ray burst prompt phase and show that the obtained range of the photon indices is compatible with the observed values and the results of Monte Carlo simulations that we carry out independently. Therefore, the observed high energy spectral indices provide a unique indicator of the jet structure.

Keywords: Theoretical models, Gamma-ray bursts, Relativistic jets, High energy astrophysics
Polar Circumtriple Planets and Disks Can Only Form Close to a Triple Star. Observations of protoplanetary disks around binary and triple star systems suggest that misalignments between the orbital plane of the stars and the disks are common. Motivated by recent observations of polar circumbinary disks, we explore the possibility of polar circumtriple disks and therefore polar circumtriple planets that could form in such a disk. With n-body simulations and analytic methods, we find that the inclusion of a third star, and the associated apsidal precession, significantly reduces the radial range of polar orbits so that circumtriple polar disks and planets can only be found close to the stellar system. Outside of a critical radius that is typically in the range of 3-10 times the outer binary separation, depending upon the binary parameters, the orbits behave the same as they do around a circular orbit binary. For some observed systems that have shorter-period inner binaries, the critical radius is considerably larger. If polar circumtriple planets can form, we suggest that it is likely that they form in a disk that was subject to breaking.

Keywords: Exoplanet dynamics, Celestial mechanics, Trinary stars, Protoplanetary disks
Overmassive Black Holes in Dwarf Galaxies Out to z 0.9 in the VIPERS Survey. Supermassive black holes (SMBHs) are thought to originate from early universe seed black holes of mass M BH ~ 102-105 M ☉ and grown through cosmic time. Such seeds could be powering the active galactic nuclei (AGN) found in today's dwarf galaxies. However, probing a connection between the early seeds and local SMBHs has not yet been observationally possible. Massive black holes hosted in dwarf galaxies at intermediate redshifts, on the other hand, may represent the evolved counterparts of the seeds formed at very early times. We present a sample of seven broad-line AGN in dwarf galaxies with a spectroscopic redshift ranging from z = 0.35 to z = 0.93. The sources are drawn from the VIPERS survey as having an Large Magellanic Cloud (LMC) like stellar mass (M ∗) derived from spectral energy distribution fitting, and they are all star-forming galaxies. Six of these sources are also X-ray AGN. The AGN are powered by SMBHs of &gt;107 M ☉, more massive than expected from the M BH-M ∗ scaling relation of AGN. Based on semianalytical simulations, we find that these objects are likely overmassive with respect to their hosts since early times (z &gt; 4), independently of whether they formed as heavy (~105 M ☉) or light (~102 M ☉) seed black holes. In our simulations, these objects tend to grow faster than their host galaxies, contradicting models of synchronized growth. The host galaxies are found to possibly evolve into massive systems by z ~ 0, indicating that local SMBHs in massive galaxies could originate in dwarf galaxies hosting seed black holes at higher z.

Keywords: Dwarf galaxies