Sazuna/UAT_keywords huggingface dataset:
The Distance to High-velocity Cloud Complex M. λ-21 cm HI4PI survey data are used to study the anomalous-velocity hydrogen gas associated with high-velocity cloud Complex M. These high-sensitivity, high-resolution, high-dynamic-range data show that many of the individual features, including MI, MIIa, and MIIb, are components of a long, arched filament that extends from about (l, b) = (105°, 53°) to (l, b) = (196°, 55°). Maps at different velocities, results from Gaussian analysis, and observations of associated high-energy emission make a compelling case that the MI cloud and the arched filament are physically interacting. If this is the case, we can use the distance to MI, 150 pc as reported by Schmelz &amp; Verschuur, to set the distance to Complex M. The estimated mass of Complex M is then about 120 M ⊙, and the energy implied using the observed line-of-sight velocity, -85 km s-1, is 8.4 × 1048 erg. Integrating over 4π sr, the total energy for a spherically symmetrical explosion is estimated to be 1.9 × 1050 erg, well within the energy budget of a typical supernova.

Keywords: High-velocity clouds, Interstellar clouds
On the Cosmic Evolution of AGN Obscuration and the X-Ray Luminosity Function: XMM-Newton and Chandra Spectral Analysis of the 31.3 deg<SUP>2</SUP> Stripe 82X. We present X-ray spectral analysis of XMM-Newton and Chandra observations in the 31.3 deg2 Stripe-82X (S82X) field. Of the 6181 unique X-ray sources in this field, we analyze a sample of 2937 candidate active galactic nuclei (AGNs) with solid redshifts and sufficient counts determined by simulations. Our results show an observed population with median values of spectral index ${\rm{\Gamma }}={1.94}_{-0.39}^{+0.31}$ , column density log $\,{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}={20.7}_{-0.5}^{+1.2}$ and intrinsic, de-absorbed, 2-10 keV luminosity log $\,{L}_{{\rm{X}}}/\mathrm{erg}\,\ {{\rm{s}}}^{-1}={44.0}_{-1.0}^{+0.7}$ , in the redshift range 0-4. We derive the intrinsic, model-independent, fraction of AGNs that are obscured ( $22\leqslant \mathrm{log}\,{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}\lt 24$ ), finding a significant increase in the obscured AGN fraction with redshift and a decline with increasing luminosity. The average obscured AGN fraction is 57% ± 4% for log L X/erg s-1 &gt; 43. This work constrains the AGN obscuration and spectral shape of the still uncertain high-luminosity and high-redshift regimes (log L X/erg s-1 &gt; 45.5, z &gt; 3), where the obscured AGN fraction rises to 64% ± 12%. We report a luminosity and density evolution of the X-ray luminosity function, with obscured AGNs dominating at all luminosities at z &gt; 2, and unobscured sources prevailing at log L X/erg s-1 &gt; 45 at lower redshifts. Our results agree with the evolutionary models in which the bulk of AGN activity is triggered by gas-rich environments and in a downsizing scenario. Moreover, the black hole accretion density (BHAD) is found to evolve similarly to the star formation rate density, confirming the coevolution between AGN and host galaxy, but suggesting different timescales in their growing history. The derived BHAD evolution shows that Compton-thick AGNs contribute to the accretion history of AGNs as much as all other AGN populations combined.

Keywords: Cosmology, Cosmological evolution, Cosmological models, Active galaxies, X-ray active galactic nuclei, Galaxy evolution, Active galactic nuclei, X-ray surveys
A Bayesian Inference of a Relativistic Mean-field Model of Neutron Star Matter from Observations of NICER and GW170817/AT2017gfo. Observations of optical and near-infrared counterparts of binary neutron star mergers not only enrich our knowledge about the abundance of heavy elements in the universe and help reveal the remnant object just after the merger, which is generally known, but can also effectively constrain the dense properties of the nuclear matter and the equation of state (EOS) in the interior of the merging stars. Following the relativistic mean-field description of nuclear matter, we perform a Bayesian inference of the EOS and the properties of the nuclear matter using the first multi-messenger event GW170817/AT2017gfo, together with the NICER mass-radius measurements of pulsars. The kilonova is described by a radiation-transfer model with the dynamical ejecta, and light curves connect with the EOS through the quasi-universal relations between the properties of the ejecta (the ejected mass, velocity, opacity, or electron fraction) and binary parameters (the mass ratio and reduced tidal deformability). It is found that the posterior distributions of the reduced tidal deformability from the AT2017gfo analysis display a bimodal structure, with the first peak enhanced by the GW170817 data, leading to slightly softened posterior EOSs, while the second peak cannot be achieved by a nuclear EOS with saturation properties in their empirical ranges. The inclusion of NICER data results in a stiffened EOS posterior because of the massive pulsar PSR J0740+6620. We provide the results at nuclear saturation density for the nuclear incompressibility, the symmetry energy, and its slope, as well as the nucleon effective mass, from our analysis of the observational data.

Keywords: Neutron stars, Gravitational waves, Pulsars
Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford-Znajek Flux. We examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (BHs), by applying our two-dimensional particle-in-cell simulation code. Assuming a stellar-mass BH, we find that the created pairs fail to screen the electric field along the magnetic field, provided that the mass accretion rate is much small compared to the Eddington limit. Magnetic islands are created by reconnection near the equator and migrate toward the event horizon, expelling magnetic flux tubes from the BH vicinity during a large fraction of time. When the magnetic islands stick to the horizon due to redshift and virtually vanish, a strong magnetic field penetrates the horizon, enabling efficient extraction of energy from the BH. During this flaring phase, a BH gap appears around the inner light surface with a strong meridional return current toward the equator within the ergosphere. If the mass accretion rate is 0.025% of the Eddington limit, the BH's spin-down luminosity becomes 16-19 times greater than its analytical estimate during the flares, although its long-term average is only 6% of it. We demonstrate that the extracted energy flux concentrates along the magnetic field lines threading the horizon in the middle latitudes. It is implied that this meridional concentration of the Poynting flux may result in the formation of limb-brightened jets from low-accreting BH systems.

Keywords: High energy astrophysics, Kerr black holes, Relativistic jets, Plasma astrophysics, General relativity, Magnetic fields
Tracing the Accretion Geometry of H1743-322 with Type C Quasiperiodic Oscillations in Multiple Outbursts. We present a systematic analysis of type C quasiperiodic oscillation (QPO) observations of H1743-322 throughout the Rossi X-ray Timing Explorer era. We find that, while different outbursts have significant flux differences, they show consistent positive correlations between the QPO fractional rms amplitude and nonthermal fraction of the emission, which indicate an independence of the intrinsic QPO rms on individual outburst brightnesses in H1743-322. However, the dependence of the QPO rms on frequency is different between the outburst rise and decay phases, where the QPO fractional rms of the decay phase is significantly lower than that of the rise phase at low frequencies. The spectral analysis also reveals different ranges of coronal temperature between the two outburst stages. A semiquantitative analysis shows that the Lense-Thirring precession model could be responsible for the QPO rms differences, requiring a variable coronal geometric shape. However, the variable-Comptonization model could also account for the findings. The fact that the rms differences and the hysteresis traces in the hardness-intensity diagram accompany each other indicates a connection between the two phenomena. By correlating the findings with QPO phase lags and the quasi-simultaneous radio flux previously published, we propose there could be corona-jet transitions in H1743-322 similar to those that have been recently reported in GRS 1915+105.

Keywords: Accretion, Black hole physics, X-ray binary stars, Stellar mass black holes
Beyond UVJ: Color Selection of Galaxies in the JWST Era. We present a new rest-frame color-color selection method using synthetic u  s  - g  s  and g  s  - i  s , (ugi) s  colors to identify star-forming and quiescent galaxies. Our method is similar to the widely used U - V versus V - J (UVJ) diagram. However, UVJ suffers known systematics. Spectroscopic campaigns have shown that UVJ-selected quiescent samples at z ≳ 3 include ~10%-30% contamination from galaxies with dust-obscured star formation and strong emission lines. Moreover, at z &gt; 3, UVJ colors are extrapolated because the rest-frame band shifts beyond the coverage of the deepest bandpasses at &lt;5 μm (typically Spitzer/IRAC 4.5 μm or future JWST/NIRCam observations). We demonstrate that (ugi) s  offers improvements to UVJ at z &gt; 3, and can be applied to galaxies in the JWST era. We apply (ugi) s  selection to galaxies at 0.5 &lt; z &lt; 6 from the (observed) 3D-HST and UltraVISTA catalogs, and to the (simulated) JAGUAR catalogs. We show that extrapolation can affect (V - J)0 color by up to 1 mag, but changes ${({g}_{s}-{i}_{s})}_{0}$ color by ≤0.2 mag, even at z ≃ 6. While (ugi) s -selected quiescent samples are comparable to UVJ in completeness (both achieve ~85%-90% at z = 3-3.5), (ugi) s  reduces contamination in quiescent samples by nearly a factor of 2, from ≃35% to ≃17% at z = 3, and from ≃60% to ≃33% at z = 6. This leads to improvements in the true-to-false-positive ratio (TP/FP), where we find TP/FP ≳2.2 for (ugi) s  at z ≃ 3.5 - 6, compared to TP/FP &lt; 1 for UVJ-selected samples. This indicates that contaminants will outnumber true quiescent galaxies in UVJ at these redshifts, while (ugi) s  will provide higher-fidelity samples.

Keywords: Surveys, Galaxy photometry, High-redshift galaxies, Catalogs
Using Neural Networks to Differentiate Newly Discovered BL Lacertae Objects and FSRQs among the 4FGL Unassociated Sources Employing Gamma-Ray, X-Ray, UV/Optical, and IR Data. Among the ~2157 unassociated sources in the third data release (DR3) of the fourth Fermi catalog, ~1200 were observed with the Neil Gehrels Swift Observatory pointed instruments. These observations yielded 238 high signal-to-noise ratio X-ray sources within the 95% Fermi uncertainty regions. Recently, Kerby et al. employed neural networks to find blazar candidates among these 238 X-ray counterparts to the 4FGL unassociated sources and found 112 likely blazar counterpart sources. A complete sample of blazars, along with their subclassification, is a necessary step to help understand the puzzle of the blazar sequence and for the overall completeness of the gamma-ray emitting blazar class in the Fermi catalog. We employed a multi-perceptron neural network classifier to identify flat spectrum radio quasars (FSRQs) and BL Lac objects among these 112 blazar candidates using the gamma-ray, X-ray, UV/optical, and IR properties. This classifier provided probability estimates for each source to be associated with one or the other category, such that P fsrq represents the probability for a source to be associated with the FSRQ subclass. Using this approach, four FSRQs and 50 BL Lac objects are classified as such with &gt;99% confidence, while the remaining 58 blazars could not be unambiguously classified as either BL Lac objects or FSRQs.

Keywords: X-ray astronomy, Blazars, Active galactic nuclei, High energy astrophysics
Gamma-Ray Emission from Galaxies Hosting Molecular Outflows. Many star-forming galaxies and those hosting active galactic nuclei show evidence of massive outflows of material in a variety of phases including ionized, neutral atomic, and molecular. Molecular outflows in particular have been the focus of recent interest as they may be responsible for removing gas from the galaxy, thereby suppressing star formation. As material is ejected from the cores of galaxies, interactions of the outflowing material with the interstellar medium can accelerate cosmic rays and produce high-energy gamma rays. In this work, we search for gamma-ray emission from a sample of local galaxies known to host molecular outflows using data collected by the Fermi Large Area Telescope. We employ a stacking technique in order to search for and characterize the average gamma-ray emission properties of the sample. Gamma-ray emission is detected from the galaxies in our sample at the 4.4σ level with a power-law photon index of Γ ≈ 2 in the 1-800 GeV energy range. The emission is found to correlate with tracers of star formation activity, namely the 8-1000 μm infrared luminosity. We also find that the observed signal can be predominantly attributed to H II galaxies hosting energy-driven outflows. While we do not find evidence suggesting that the outflows are accelerating charged particles directly, galaxies with molecular outflows may produce more gamma rays than galaxies without outflows. In particular, the set consisting of gamma-ray-detected galaxies with molecular outflows are nearly perfect calorimeters and may be future targets for searches of high-energy neutrinos.

Keywords: AGN host galaxies, Galactic winds, High energy astrophysics, Gamma-rays, Particle astrophysics, Cosmic rays
Quasi-parallel Whistler Waves and Their Interaction with Resonant Electrons during High-velocity Bulk Flows in the Earth's Magnetotail. In collisionless space, plasma waves are important channels of energy conversion, affecting the local particle velocity distribution functions through wave-particle interactions. In this paper we present a comparative statistical analysis of the characteristics of quasi-parallel narrowband whistler waves and the properties of resonant electrons interacting with these waves during the intervals of earthward and tailward high-velocity bulk flows produced by the near-Earth X-line and observed by Magnetospheric Multiscale Mission spacecraft. We found that on both sides of the X-line, the suprathermal electrons (≥1 keV) having large pitch angles make the major contribution to the maximal growth rate (γ) of these waves. The whistler waves were observed almost simultaneously with strong enhancements of perpendicular magnetic gradients localized at electron scales near dipolarization fronts associated with the earthward bulk flows, and near flux ropes/magnetic islands embedded into the tailward bulk flows. Betatron energization of electrons due to the appearance of such gradients increases the perpendicular anisotropy of electron distribution, which could be responsible for the whistler wave generation. We found that in the course of electron interactions with the whistler waves the lower-energy resonant electrons can transfer a part of their kinetic energy to the higher-energy electrons, especially in the Central Plasma Sheet. This results in formation/enhancement of energy-dependent perpendicular anisotropy and power-law tails in the high-energy range of electron velocity distribution. We conclude that despite the differences in the magnetic structure of the earthward and tailward bulk flows, the mechanisms of the quasi-parallel whistler wave generation and the properties of resonant electrons are quite similar.

Keywords: Planetary magnetospheres, Space plasmas
The Event Horizon Telescope Image of the Quasar NRAO 530. We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5-7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of ~20 μas, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ~5%-8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle ~ -28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin.

Keywords: Extragalactic astronomy
Possible Gravitational Microlensing Events in the Optical Lightcurve of Active Galaxy S5 0716+714. A well-known active galaxy of the blazar type, S5 0716+714, is characterized by a particularly high-variability duty cycle on short timescales at optical frequencies. As such, the source was subjected to numerous monitoring programs, including both ground-based as well as spaceborne telescopes. On closer inspection of the most recent accumulation of the data provided by the Transiting Exoplanet Survey Satellite, we have noticed several conspicuous events with "volcano-like" symmetric shape, all lasting for several hours, which closely resemble the achromatic events detected with the previous Whole Earth Blazar Telescope campaigns targeting the source. We propose that those peculiar features could be due to the gravitational microlensing of the innermost segments of the precessing jet in the system by a binary lens. We study the magnification pattern of the lens with the inverse-ray shooting method and the source trajectory parameters with the Python package MULENSMODEL. In this way, we were able to fit successfully all the selected events with a single lens, adjusting slightly only the source trajectory parameters for each lensing event. Based on the fit results, we postulate the presence of a massive binary lens containing an intermediate-mass black hole, possibly even a supermassive one, and a much less massive companion (by a factor of ≲0.01) located within the host galaxy of the blazar, most likely the central kiloparsec region. We discuss the major physical implications of the proposed scenario regarding the quest for the intermediate-mass and dual supermassive black holes in active galaxies.

Keywords: Black holes, Blazars, Active galaxies, Active galactic nuclei, Gravitational lensing
Molecular Hydrogen and its Proxies HCO<SUP>+</SUP> and CO in the Diffuse Interstellar Medium. There is a robust polyatomic chemistry in diffuse, partially molecular interstellar gas that is readily accessible in absorption at radio/millimeter/submillimeter wavelengths. Accurate column densities are derived owing to the weak internal excitation, so relative molecular abundances are well known with respect to each other but not with respect to H2. Here we consider the use of proxies for hydrogen column densities N(H2) and N(H) = N(H I)+2N(H2) based on measurements of HCO+ absorption and CO emission and absorption, and we compare these with results obtained by others when observing H I, H2 and CO toward stars and active galactic nuclei. We consider the use of HCO+ as a proxy for H2 and show that the assumption of a relative abundance N(H2) = N(HCO+)/3 × 10-9 gives the same view of the atomic-molecular hydrogen transition that is seen in UV absorption toward stars. CO on the other hand shows differences between the radio and optical regimes because emission is always detected when N(HCO+) ≳ 6 × 1011 cm-2 or N(H2) ≳ 2 × 1020 cm-2. Wide variations in the integrated CO J = 1 - 0 brightness WCO and N(CO)/N(H2) imply equivalent variations in the CO-H2 conversion factor even while the ensemble mean is near the usual Galactic values. Gas/reddening ratios found in absorption toward stars, N(H)/E(B - V) = 6.2 × 1021 H cm-2 (mag)-1 overall or 6.8 × 1021 H cm-2 (mag)-1 for sightlines at E(B - V) ≤ 0.08 mag lacking H2 are well below the Galactic mean measured at low reddening and high Galactic latitude, 8.3 × 1021 H cm-2 (mag)-1.

Keywords: Interstellar molecules, Interstellar atomic gas, Diffuse interstellar clouds
A New Component from the Quiet Sun from Radio to Gamma Rays: Synchrotron Radiation by Galactic Cosmic-Ray Electrons. The quiet Sun, i.e., in its nonflaring state or nonflaring regions, emits thermal radiation from radio to ultraviolet. The quiet Sun also produces nonthermal radiation observed in gamma rays due to interactions of Galactic cosmic rays (GCRs) with the solar atmosphere and photons. We report on a new component: the synchrotron emission by GCR electrons in the solar magnetic field. To the best of our knowledge this is the first time this emission has been theoretically claimed and modeled. We find that the measured GCR electrons with energies from tens of GeV to a few TeV produce synchrotron emission in X-rays, which is a few orders of magnitude lower than current upper limits of the quiet Sun set by RHESSI and FOXSI, with no energy losses included. For a radially decreasing solar magnetic field we find the expected synchrotron intensity to be almost constant in the solar disk, to peak in the close proximity of the Sun, and to quickly drop away from the Sun. We also estimate the synchrotron emission from radio to gamma rays, and we compare it with current observations, especially with LOFAR. While it is negligible from radio to UV compared to the solar thermal radiation, this emission can potentially be observed at high energies with NuSTAR and more promising future FOXSI observations. This could potentially allow for constraining GCR densities and magnetic-field intensities at the Sun. This study provides a more complete description and a possible new way for understanding the quiet Sun and its environment.

Keywords: High-energy cosmic radiation, Quiet sun, Solar x-ray emission, Galactic cosmic rays, Solar radio emission, Cosmic rays