Sazuna/UAT_keywords huggingface dataset:
A Catalog of 406 AGNs in MaNGA: A Connection between Radio-mode AGNs and Star Formation Quenching. Accurate active galactic nucleus (AGN) identifications and spatially resolved host galaxy properties are a powerful combination for studies of the role of AGNs and AGN feedback in the coevolution of galaxies and their central supermassive black holes. Here, we present robust identifications of 406 AGNs in the first 6261 galaxies observed by the integral field spectroscopy survey Mapping Nearby Galaxies at Apache Point Observatory. Instead of using optical line flux ratios, which can be difficult to interpret in light of the effects of shocks and metallicity, we identify the AGNs via mid-infrared Wide-field Infrared Survey Explorer colors, Swift/BAT ultrahard X-ray detections, NVSS and FIRST radio observations, and broad emission lines in SDSS spectra. We subdivide the AGNs into radio-quiet and radio-mode AGNs, and examine the correlations of the AGN classes with host galaxy star formation rates and stellar populations. When compared to the radio-quiet AGN host galaxies, we find that the radio-mode AGN host galaxies are preferentially elliptical, lie further beneath the star-forming main sequence (with lower star formation rates at fixed galaxy mass), have older stellar populations, and have more negative stellar age gradients with galactocentric distance (indicating inside-out quenching of star formation). These results establish a connection between radio-mode AGNs and the suppression of star formation.

Keywords: Active galaxies, Star formation, Radio galaxies
Particle-in-cell Simulations of Decaying Plasma Turbulence: Linear Instabilities versus Nonlinear Processes in 3D and 2.5D Approximations. Particle-in-cell (PIC) simulations are used to examine the decay of strongly intermittent Alfvénic turbulence in a collisionless, homogeneous, and magnetized plasma. Results from three computational models are compared in simulations with similar plasma parameters and dimensions of approximately 100 di, where di is the ion inertial length. Each model utilizes three-dimensional velocities, but spatial variations differ: the 2.5D perpendicular PIC model uses two-dimensional spatial variations with the background magnetic field Bo perpendicular to the simulation plane, the 2.5D parallel PIC model uses two-dimensional spatial variations with Bo in the simulation plane, and the 3D model includes spatial variations in full three-dimensional space. Results from the three models are compared using plots of the joint probability distribution functions (PDFs) of maximum local linear instability growth rates versus the maximum local nonlinear frequencies. All results agree with previous demonstrations that linear growth rates are generally slower than the nonlinear frequencies of the turbulence at kdi = 1.0. However, it is the 3D PIC joint PDFs that most closely resemble joint PDFs recently observed in space plasmas because the 3D PDFs capture both the linear and nonlinear plasma processes, whereas the 2.5D parallel PIC runs do not represent the nonlinear turbulence processes and the 2.5D perpendicular PIC computations do not well represent the consequences of microinstabilities. These results suggest that 3D simulations are needed to properly capture important features of both microinstabilities and nonlinear turbulence.

Keywords: Interplanetary turbulence, Solar wind
A Hard Look at Local, Optically Selected, Obscured Seyfert Galaxies. We study the X-ray spectra of a sample of 19 obscured, optically selected Seyfert galaxies (Sy 1.8, 1.9, and 2) in the local universe (d ≤ 175 Mpc), drawn from the CfA Seyfert sample. Our analysis is driven by the high sensitivity of NuSTAR in the hard X-rays, coupled with soft X-ray spectra using XMM-Newton, Chandra, Suzaku, and Swift/XRT. We also analyze the optical spectra of these sources in order to obtain accurate mass estimates and Eddington fractions. We employ four different models to analyze the X-ray spectra of these sources, which all provide consistent results. We find that 79%-90% of the sources are heavily obscured with line-of-sight column density NH &gt; 1023 cm-2. We also find a Compton-thick (NH &gt; 1024 cm-2) fraction of 37%-53%. These results are consistent with previous estimates based on multiwavelength analyses. We find that the fraction of reprocessed to intrinsic emission is positively correlated with NH and negatively correlated with the intrinsic, unabsorbed X-ray luminosity (in agreement with the Iwasawa-Taniguchi effect). Our results support the hypothesis that radiation pressure regulates the distribution of the circumnuclear material. * Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 099.A-0403.

Keywords: X-ray astronomy, High energy astrophysics, Active galaxies, Seyfert galaxies, X-ray active galactic nuclei, Active galactic nuclei, X-ray surveys
Probing Magnetic Field Morphology in Galaxy Clusters with the Gradient Technique. Magnetic fields in the intracluster medium affect the structure and the evolution of galaxy clusters. However, their properties are largely unknown, and measuring magnetic fields in galaxy clusters is challenging, especially on large scales outside of individual radio sources. In this work, we probe the plane-of-the-sky orientation of magnetic fields in clusters using the intensity gradients. The technique is a branch of the gradient technique (GT) that employs emission intensity maps from turbulent gas. We utilize Chandra X-ray images of the Perseus, M87, Coma, and A2597 galaxy clusters, and the VLA radio observations of the synchrotron emission from Perseus. We find that the fields predominantly follow the sloshing arms in Perseus, which is in agreement with numerical simulations. The GT-predicted magnetic field shows signatures of magnetic draping around rising bubbles driven by supermassive black hole feedback in the centers of cool-core clusters, as well as draping around substructures merging with the Coma cluster. We calculate the mean-field orientation with respect to the radial direction in these clusters. In the central regions of cool-core clusters, the mean orientation of the magnetic fields is preferentially azimuthal. There is broad agreement between the magnetic field of Perseus predicted using the X-ray and radio data. Further numerical studies and better future observations with higher resolution and larger effective area will help reduce the uncertainties of this method.

Keywords: Galaxy clusters, Magnetohydrodynamics, Intracluster medium, Extragalactic magnetic fields
Probing the Growth of Massive Black Holes with Black Hole-Host Galaxy Spin Correlations. Supermassive black holes are commonly found at the centers of their host galaxies, but their formation still remains an open question. In light of the tight correlation between the black hole (BH) mass and the velocity dispersions of the bulge component of the host galaxy, a BH-host galaxy coevolution scenario has been established. Such a description, however, still contains many theoretical uncertainties, including puzzles about the formation of BH seeds at high redshifts and the growth channel fueling these seeds. In this work, we systematically analyze the signatures of different growth channels on massive BH (MBH) spins. We show that different growth channels can be partially distinguished with the magnitudes of MBH spins inferred from extreme-mass-ratio inspirals detected by the Laser Interferometer Space Antenna. In addition, we propose measuring the correlation between the directions of MBH spins and their host galaxy spins, which is possible for extreme-mass-ratio inspirals happening in low-redshift galaxies ( $z\leqslant 0.3$ ). With the inclusion of spin direction correlation different formation channels shall be significantly better constrained.

Keywords: Supermassive black holes, Gravitational waves, Galaxy mergers, Gravitational wave sources
Discovery of 18 Stars with -3.10 &lt; [Fe/H] &lt; -1.45 in the Sagittarius Dwarf Galaxy. Studies of the early chemical evolution of some larger dwarf galaxies (&gt;107 M⊙) are limited by the small number of stars known at low metallicities in these systems. Here we present metallicities and carbon abundances for eighteen stars with metallicities between -3.08 ≤ [Fe/H] ≤ -1.47 in the Sagittarius dwarf spheroidal galaxy, using medium-resolution spectra from the MagE spectrograph on the Magellan-Baade Telescope. This sample more than doubles the number of known very metal-poor stars ([Fe/H] ≤ -2.0) in the Sagittarius dwarf galaxy, and identifies one of the first known extremely metal-poor stars ([Fe/H] ≤ -3.0) in the system. These stars were identified as likely metal-poor members of Sagittarius using public, metallicity-sensitive photometry from SkyMapper DR1.1 and proper motion data from Gaia DR2, demonstrating that this dearth of metal-poor stars in some dwarf galaxies can be addressed with targeted searches using public data. We find that none of the stars in our sample are enhanced in carbon, in contrast to the relative prevalence of such stars in the Milky Way halo. Subsequent high-resolution spectroscopy of these stars would be key in detailing the early chemical evolution of the system. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Population II stars, Sagittarius dwarf spheroidal galaxy, Dwarf galaxies
Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB ∼ 180916.J0158+65. We report on simultaneous radio and X-ray observations of the repeating fast radio burst source FRB 180916.J0158+65 using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Effelsberg, and Deep Space Network (DSS-14 and DSS-63) radio telescopes and the Chandra X-ray Observatory. During 33 ks of Chandra observations, we detect no radio bursts in overlapping Effelsberg or Deep Space Network observations and a single burst during CHIME/FRB source transits. We detect no X-ray events in excess of the background during the Chandra observations. These non-detections imply a 5σ limit of &lt;5 × 10-10 erg cm-2 for the 0.5-10 keV fluence of prompt emission at the time of the radio burst and 1.3 × 10-9 erg cm-2 at any time during the Chandra observations. Given the host-galaxy redshift of FRB 180916.J0158+65 (z ∼ 0.034), these correspond to energy limits of &lt;1.6 × 1045 erg and &lt;4 × 1045 erg, respectively. We also place a 5σ limit of &lt;8 × 10-15 erg s-1 cm-2 on the 0.5-10 keV absorbed flux of a persistent source at the location of FRB 180916.J0158+65. This corresponds to a luminosity limit of &lt;2 × 1040 erg s-1. Using an archival set of radio bursts from FRB 180916.J0158+65, we search for prompt gamma-ray emission in Fermi/GBM data but find no significant gamma-ray bursts, thereby placing a limit of 9 × 10-9 erg cm-2 on the 10-100 keV fluence. We also search Fermi/LAT data for periodic modulation of the gamma-ray brightness at the 16.35 days period of radio burst activity and detect no significant modulation. We compare these deep limits to the predictions of various fast radio burst models, but conclude that similar X-ray constraints on a closer fast radio burst source would be needed to strongly constrain theory.

Keywords: Neutron stars, X-ray bursts, High energy astrophysics, Radio transient sources
Temperature Structures of Embedded Disks: Young Disks in Taurus Are Warm. The chemical composition of gas and ice in disks around young stars sets the bulk composition of planets. In contrast to protoplanetary disks (Class II), young disks that are still embedded in their natal envelope (Class 0 and I) are predicted to be too warm for CO to freeze out, as has been confirmed observationally for L1527 IRS. To establish whether young disks are generally warmer than their more evolved counterparts, we observed five young (Class 0/I and I) disks in Taurus with the Atacama Large Millimeter/submillimeter Array, targeting C17O 2 - 1, H2CO ${3}_{\mathrm{1,2}}-{2}_{\mathrm{1,1}}$ , HDO ${3}_{\mathrm{1,2}}-{2}_{\mathrm{2,1}}$ , and CH3OH 5K - 4K transitions at 0"48 × 0"31 resolution. The different freeze-out temperatures of these species allow us to derive a global temperature structure. C17O and H2CO are detected in all disks, with no signs of CO freeze-out in the inner ∼100 au and a CO abundance close to ∼10-4. The H2CO emission originates in the surface layers of the two edge-on disks, as witnessed by the especially beautiful V-shaped emission pattern in IRAS 04302+2247. HDO and CH3OH are not detected, with column density upper limits more than 100 times lower than for hot cores. Young disks are thus found to be warmer than more evolved protoplanetary disks around solar analogs, with no CO freeze-out (or only in the outermost part of ≳100 au disks) or processing. However, they are not as warm as hot cores or disks around outbursting sources and therefore do not have a large gas-phase reservoir of complex molecules.

Keywords: Protostars, Young stellar objects, Protoplanetary disks, Astrochemistry
Mirror Instability Driven by Pickup Ions in the Outer Heliosheath. The stability of the pickup ions in the outer heliosheath is a vital factor in the generation of the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer according to the secondary ENA mechanism. Most previous studies of the pickup ion stability assumed simple, idealized velocity distributions of the pickup ions and focused on the parallel-propagating modes only. This paper takes a more realistic multicomponent pickup ion velocity distribution given by the global modeling of neutral atoms in the heliosphere and investigates the role of the oblique mirror waves, in addition to the parallel modes. Both linear kinetic instability analysis and hybrid simulations are performed. In contrast to a recent investigation using the same distribution that demonstrated the growth of parallel waves but reported an insignificant contribution of oblique modes, our study reveals substantial growth of the oblique mirror instability. The oblique mirror modes and the parallel/quasi-parallel ion cyclotron waves grow simultaneously with different growth rates. The pickup ion scattering by two types of excited waves together is more pronounced than by either type of wave alone. More importantly, our two-dimensional hybrid simulation results demonstrate that the development of the mirror instability not only produces its own pickup ion scattering, but also leads to the growth of extra ion cyclotron waves (in a quasi-linear manner), which further enhances the pickup ion scattering. The results suggest an important role of the mirror modes that should not be ignored in the stability study of the outer heliosheath pickup ions.

Keywords: Heliopause, Heliosheath, Heliosphere, Pickup ions
Completing the Census of AGN in GOODS-S/HUDF: New Ultradeep Radio Imaging and Predictions for JWST. A global understanding of active galactic nuclei (AGN) and their host galaxies hinges on completing a census of AGN activity without selection biases down to the low-luminosity regime. Toward that goal, we identify AGN within faint radio populations at cosmic noon selected from new ultradeep, high-resolution imaging from the Karl G. Jansky Very Large Array at 6 and 3 GHz. These radio data are spatially coincident with the ultradeep legacy surveys in the GOODS-S/HUDF region, particularly the unparalleled Chandra 7 Ms X-ray imaging. Combined, these data sets provide a unique basis for a thorough census of AGN, allowing simultaneous identification via (1) high X-ray luminosity, (2) hard X-ray spectra, (3) excess X-ray relative to 6 GHz, (4) mid-IR colors, (5) SED fitting, (6) radio excess via the radio-infrared relation, (7) flat radio spectra via multiband radio, and (8) optical spectroscopy. We uncover AGN in fully half our faint radio sample, indicating a source density of one AGN arcmin-2, with a similar number of radio-undetected AGN identified via X-ray over the same area. Our radio-detected AGN are majority radio-quiet, with radio emission consistent with being powered predominantly by star formation. Nevertheless, we find AGN radio signatures in our sample: ∼12% with radio excess indicating radio-loud activity, and ∼16% of radio-quiet AGN candidates with flat or inverted radio spectra. The latter is a lower limit, pending our upcoming deeper 3 GHz survey. Finally, despite these extensive data sets, this work is likely still missing heavily obscured AGN. We discuss in detail this elusive population and the prospects for completing our AGN census with James Webb Space Telescope/MIRI.

Keywords: Radio continuum emission, Radio galaxies, Active galactic nuclei, High-redshift galaxies
Magnetic Activity and Period Variation Studies of the Four W Uma-type Eclipsing Binaries: UV Lyn, V781 Tau, NSVS 4484038, and 2MASS J15471055+5302107. We present new photometric data and LAMOST spectra for the W UMa binaries UV Lyn, V781 Tau, NSVS 4484038, and 2MASS J15471055+5302107. The orbital and starspot parameters are obtained using the Wilson-Devinney program. Comparing the starspot parameters at different times, there are magnetic activities in these four binaries. The orbital period of UV Lyn is increasing at a rate of dP/dt = +8.9(5) × 10-8 days yr-1, which maybe due to mass transfer from the less massive component to the more massive component (dM1/dt = -6.4 × 10-8 M⊙ yr-1). The period variation of 2MASS J15471055+5302107 is also increasing at a rate of 6.0(4) × 10-7 days yr-1, which can be explained by mass transfer from the less massive component to the more massive component (dM1/dt = -2.8 × 10-7 M⊙ yr-1). The period variation of V781 Tau presents the downward parabola superimposed the cyclic oscillation. The period of V781 Tau is decreasing (dP/dt = -3.2(4) × 10-8 days yr-1), which can be explained by mass transfer from the more massive component to the less massive component (dM2/dt = -2.2 × 10-8 M⊙ yr-1). The cyclic oscillation may be due to the magnetic activity with a period of 30.8(5) yr rather than a third body. The period variation of NSVS 4484038 also shows the cyclic oscillation, which could be explained by the magnetic activity with 10.8(1) yr or a black hole candidate. Interestingly, there is a depth variation between the light minimum times of NSVS 4484038, which may also be caused by stellar magnetic activity.

Keywords: Eclipsing binary stars, Starspots, Contact binary stars
Orbital Dynamics with the Gravitational Perturbation due to a Disk. The secular behavior of an orbit under gravitational perturbation due to a two-dimensional uniform disk is studied in this paper, through analytical and numerical approaches. We develop the secular approximation of this problem and obtain the averaged Hamiltonian for this system first. We find that when the ratio of the semimajor axes of the inner orbit and the disk radius takes a very small value (≪1), and if the inclination between the inner orbit and the disk is greater than the critical value of 30°, the inner orbit will undergo the (classical) Lidov-Kozai resonance in which variations of eccentricity and inclination are usually very large and the system has two equilibrium points at ω = π/2, 3π/2 (ω is the argument of perihelion). The critical value will slightly drop to about 27° as the ratio increases to 0.4. However, the secular resonances will not occur for the outer orbit and the variations of the eccentricity and inclination are small. When the ratio of the orbit and the disk radius is nearly 1, there are many more complicated Lidov-Kozai resonance types which lead to orbital behaviors that are different from the classical Lidov-Kozai case. In these resonances, the system has more equilibrium points which could appear at ω = 0, π/2, π, 3π/2, and even other values of ω. The variations of eccentricity and inclination become relatively moderate, moreover, and in some cases the orbit can be maintained at a highly inclined state. In addition, an analysis shows that a Kuzmin disk can also lead to the (classical) Lidov-Kozai resonance, and the critical inclination is also 30°.

Keywords: Orbital resonances, Orbital evolution, Galaxy disks, Celestial mechanics, Protoplanetary disks
Constraining the Bulk Composition of Disintegrating Exoplanets Using Combined Transmission Spectra from JWST and SPICA. Disintegrating planets are ultrashort-period exoplanets that appear to have a comet-like dust tail. They are commonly interpreted as low-mass planets whose solid surface is evaporating, and whose tails are made of recondensing minerals. Transmission spectroscopy of the dust tails could thus allow us to directly probe the elementary compositions of these planets. Previous work already investigated the feasibility of such observations using the James Webb Space Telescope (JWST) mid-infrared instrument. In this study, we explore if one can obtain a strong constrain on the tail composition by adding spectroscopy at longer wavelengths using the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) mid-infrared instrument. We use a simple model for the spatial distribution of the dust tails and produce their synthetic transmission spectra assuming various dust compositions. We find that combined infrared spectra from JWST and SPICA will allow us to diagnose various components of the dust tails. JWST will be able to detect silicate and carbide absorption features with a feature-to-noise ratio of ≳3 in the tail transmission spectrum of a disintegrating planet located within 100 pc from the Earth, with a transit depth deeper than 0.5%. SPICA can distinguish between Fe- and Mg-bearing crystalline silicates for planets at ≲100 pc with a transit depth of ≳2%. Transit searches with current and future space telescopes (e.g., TESS and PLATO) will provide ideal targets for such spectroscopic observations.

Keywords: Exoplanet astronomy, Transmission spectroscopy
The White Dwarf Opportunity: Robust Detections of Molecules in Earth-like Exoplanet Atmospheres with the James Webb Space Telescope. The near-term search for life beyond the solar system currently focuses on transiting planets orbiting small M dwarfs, and the challenges of detecting signs of life in their atmospheres. However, planets orbiting white dwarfs (WDs) would provide a unique opportunity to characterize rocky worlds. The discovery of the first transiting giant planet orbiting a WD, WD 1856+534, showed that planetary-mass objects can survive close-in orbits around WDs. The large radius ratio between WD planets and their host renders them exceptional targets for transmission spectroscopy. Here, we explore the molecular detectability and atmospheric characterization potential for a notional Earth-like planet, evolving in the habitable zone of WD 1856+534, with the James Webb Space Telescope (JWST). We establish that the atmospheric composition of such Earth-like planets orbiting WDs can be precisely retrieved with JWST. We demonstrate that robust &gt;5σ detections of H2O and CO2 can be achieved in a five-transit reconnaissance program, while the biosignatures O3 + CH4 and CH4 + N2O can be detected to &gt;4σ in as few as 25 transits. N2 and O2 can be detected to &gt;5σ within 100 transits. Given the short transit duration of WD habitable zone planets (∼2 minutes for WD 1856+534), conclusive molecular detections can be achieved in a small or medium JWST transmission spectroscopy program. Rocky planets in the WD habitable zone therefore represent a promising opportunity to characterize terrestrial planet atmospheres and explore the possibility of a second genesis on these worlds.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric composition , Bayesian statistics, White dwarf stars, Molecular spectroscopy, Transmission spectroscopy, Habitable planets, Exoplanet atmospheres