Sazuna/UAT_keywords huggingface dataset:
The Impact of Low-luminosity AGNs on Their Host Galaxies: A Radio and Optical Investigation of the Kiloparsec-scale Outflow in MaNGA 1-166919. One way an active galactic nucleus (AGN) influences the evolution of their host galaxy is by generating a large-scale (kiloparsec-scale) outflow. The content, energetics, and impact of such outflows depend on the properties of both the AGN and host galaxy, and understanding the relationship between them requires measuring the properties of all three. In this paper, we do so by analyzing recent radio and optical integral field unit spectroscopic observations of MaNGA 1-166919. Our results indicate that the biconical outflow in this galaxy is powered by a low-luminosity, low Eddington ratio AGN ejecting material that drives ~100-200 km s-1 shocks into the surrounding interstellar medium-producing the hot, ionized gas and relativistic particles associated with the observed outflow. The energetics of the relativistic and ionized gas material produced at this shock are comparable, and both the mass outflow and kinetic power of the ionized gas in this outflow are higher than other AGNs with similar bolometric luminosities. Lastly, while the host galaxy's total star formation rate is comparable to that of other star-forming galaxies with a similar stellar mass, there is evidence that the outflow both suppresses and enhances star formation in its immediate surroundings.

Keywords: AGN host galaxies, LINER galaxies, Low-luminosity active galactic nuclei, Active galactic nuclei, Radio continuum emission
H<SUB>2</SUB> Rovibrational Excitation in Protoplanetary Disks and Its Effects on the Chemistry. The effect of H2 rovibrational excitation on the chemistry of protoplanetary disks is studied using a framework that solves for the disk physical and chemical structure and includes a detailed calculation of H2 level populations. Chemistry with rovibrationally excited H2 is found to be important for the formation of several commonly observed species in disks and this work demonstrates the need to accurately treat photon-dominated-region chemistry in disks if we are to make inferences on the chemical state of the disk during planet formation epochs. This is found to be even more critical for molecules like C2H, CN, or HCN that are commonly used to infer changes in the elemental disk C/O and N/O ratios, with implications for planetesimal formation and the composition of exoplanet atmospheres. Computed vertical column densities with the full H2 population calculation are increased by ~1-2 orders of magnitude for molecules such as CN and HCN/HNC compared to calculations with no treatment of excited H2. For the commonly used pseudo-level approximation, the computed columns of these molecules are overestimated by a factor of ~3-5 when compared to the full model. We further note that the computed abundance for these molecules strongly depends on the strength of the FUV photons at energies that pump H2 (i.e., 11-13.6 eV), which is not well constrained in disks, and that rate constants as a function of H2 rovibrational levels for the key reaction N + H2 → NH are needed for a more accurate assessment of CN/HCN chemistry but are currently unavailable.

Keywords: Star formation, Protoplanetary disks, Chemical abundances, Astrochemistry
Statistical Properties of Small-scale Linear Magnetic Holes in the Martian Magnetosheath. The small-scale linear magnetic hole (LMH) is a magnetic dip with a size less than or on the order of ρi (proton gyroradius), which may contribute to turbulence properties in the solar wind and other astrophysical plasmas. Based on one-month measurements of the Mars Atmosphere and Volatile EvolutioN mission, 174 small-scale LMH events in the Martian magnetosheath are used to investigate their statistical properties in this study. Our results show that small-scale linear LMHs are ubiquitous in the Martian magnetosheath, and their occurrence rate is estimated to be approximately 1.5 events per hour based on one-month observations. Compared with the ambient plasma, the averaged magnitude of the magnetic field in these holes can decrease from 6.8-3.5 nT. Nearly 66% of events have a Bmin/B value in the range of (0.45, 0.75). The duration of small-scale MHs is mainly less than 0.4 s. For 90% of the events, the size along the solar wind flow is less than ρi. As the rotation angle increases, the occurrence rate of small-scale LMHs decrease. However, the Bmin/B, size, and duration of small-scale LMHs have no obvious dependence on their rotation angle.

Keywords: Space plasmas, Mars
Accurate Gaunt Factors for Nonrelativistic Quadrupole Bremsstrahlung. The exact result for nonrelativistic quadrupole bremsstrahlung in a Coulomb field was established only recently in Pradler &amp; Semmelrock. It requires the evaluation and integration of hypergeometric functions across a wide range of parameters and arguments, which, in practice, is unfeasible. Here we provide a highly accurate tabulation of the Gaunt factor for quadrupole radiation, its thermal average in a Maxwellian plasma, and the associated cooling function over the entire kinematically relevant range. In addition, we provide a simple approximate formula for the emission cross section that works to within a few percent accuracy for all practical purposes. The results can be applied to the scattering of electrons with themselves, for which quadrupole radiation is the dominant process.

Keywords: Interstellar thermal emission, Interstellar emissions, Interstellar medium
A Signature of 27 day Solar Rotation in the Concentration of Metallic Ions within the Terrestrial Ionosphere. We present observations during the interval 2006-2014 of 27 day and 13.5 day periodic oscillations in the ionospheric sporadic E (Es) layer. This is a thin, dense layer composed of metallic ions in the Earth's upper atmosphere between 90 and 130 km. Lomb-Scargle spectral and wavelet analyses reveal that these pronounced periodicities observed from ground-based ionosondes and GPS/GNSS radio occultations are associated with high-speed solar winds generated from persistent coronal holes on successive 27 day solar rotations. The 27 day and 13.5 day oscillations in the Es layers are dependent on latitude, showing a higher magnitude of periodicities at low latitudes between 0° and 15° and at high latitudes between 45° and 90° (10%-14%) than those at midlatitudes between 15° and 45° (4%-10%). The 27 day and 13.5 day oscillations in the high-latitude Es layers correlate well with the geomagnetic activity Dst and Ap indices, and these periodic oscillations become more significant at the solar maximum (2000-2003 and 2011-2014) than at the solar minimum.

Keywords: Solar-terrestrial interactions, Ionospheric scintillation, E layer, Earth ionosphere
Can Small-scale Magnetic Fields Be the Major Cause for the Near-surface Effect of the Solar p-mode Frequencies?. Small-scale magnetic fields are not only the fundamental element of the solar magnetism but also closely related to the structure of the solar atmosphere. The observations have shown that there is a ubiquitous tangled small-scale magnetic field with a strength of 60-130 G in the canopy-forming layer of the quiet solar photosphere. On the other hand, the multidimensional MHD simulations show that the convective overshooting expels the magnetic field to form the magnetic canopies at a height of about 500 km in the upper photosphere. However, the distribution of such small-scale "canopies" in the solar photosphere cannot be rigorously constrained by either observations or numerical simulations. Based on stellar standard models, we identify that these magnetic canopies can act as a global magnetic arch splicing layer, and we find that the reflections of the solar p-mode oscillations at this magnetic arch splicing layer result in significant improvement on the discrepancy between the observed and calculated p-mode frequencies. The location of the magnetic arch splicing layer is determined at a height of about 630 km, and the inferred strength of the magnetic field is about 90 G. These features of the magnetic arch splicing layer derived independently in the present study are quantitatively in agreement with the presence of small-scale magnetic canopies such as those obtained by the observations and 3D MHD simulations.

Keywords: Solar atmosphere, Solar convective zone, Solar magnetic fields, Solar oscillations
Estimating the Black Hole Spin for the X-Ray Binary MAXI J1820+070. MAXI J1820+070 is a newly discovered black hole X-ray binary, whose dynamical parameters, namely the black hole mass, the inclination angle, and the source distance, have recently been estimated. Insight-HXMT have observed its entire outburst from 2018 March 14. In this work, we attempted to estimate the spin parameter a*, using the continuum-fitting method and applying a fully relativistic thin disk model to the soft-state spectra obtained by Insight-HXMT. It is well known that a* is strongly dependent on three dynamical parameters in this method, and we have examined two sets of parameters. Adopting our preferred parameters: M = ${8.48}_{-0.72}^{+0.79}\,{M}_{\odot }$, i = 63° ± 3°, and D = 2.96 ± 0.33 kpc, we found a slowly spinning black hole of a* = 0.14 ± 0.09 (1σ), which gives a prograde spin parameter as the majority of other systems show. It is also possible for the black hole to have a retrograde spin (less than 0) if different dynamical parameters are taken.

Keywords: Black hole physics, X-ray binary stars
The Growth of Protoplanets via the Accretion of Small Bodies in Disks Perturbed by the Planetary Gravity. Planets grow via the collisional accretion of small bodies in a protoplanetary disk. Such small bodies feel strong gas drag, and their orbits are significantly affected by the gas flow and atmospheric structure around the planet. We investigate the gas flow in the protoplanetary disk perturbed by the gravity of the planet by 3D hydrodynamical simulation. We then calculate the orbital evolutions of particles in the gas structure obtained from the hydrodynamical simulation. Based on the orbital calculations, we obtain the collision rate between the planet and centimeter-to-kilometer-sized particles. Our results show that meter-sized or larger particles effectively collide with the planet owing to the atmospheric gas drag, which significantly enhances the collision rate. On the other hand, the gas flow plays an important role for smaller particles. Finally, considering the effects of the atmosphere and gas flow, we derive the new analytic formula for the collision rate, which is in good agreement with our simulations. We estimate the growth timescale and accretion efficiency of drifting bodies for the formation of a gas giant solid core using the formula. We find that the accretion of sub-kilometer-sized bodies achieves a short growth timescale (~0.05 Myr) and a high accretion efficiency (~1) for the core formation at 5 au in the minimum-mass solar nebula model.

Keywords: Protoplanetary disks, Planet formation
The Detectability of Kiloparsec-scale Dual Active Galactic Nuclei: The Impact of Galactic Structure and Black Hole Orbital Properties. Observational searches for dual active galactic nuclei (dAGNs) at kiloparsec separations are crucial for understanding the role of galaxy mergers in the evolution of galaxies. In addition, kiloparsec-scale dAGNs may serve as the parent population of merging massive black hole (MBH) binaries, an important source of gravitational waves. We use a semi-analytical model to describe the orbital evolution of unequal mass MBH pairs under the influence of stellar and gaseous dynamical friction in post-merger galaxies. We quantify how the detectability of approximately 40,000 kpc-scale dAGNs depends on the structure of their host galaxies and the orbital properties of the MBH pair. Our models indicate that kiloparsec-scale dAGNs are most likely to be detected in gas-rich post-merger galaxies with smaller stellar bulges and relatively massive, rapidly rotating gas disks. The detectability is also increased in systems with MBHs of comparable masses following low eccentricity prograde orbits. In contrast, dAGNs with retrograde, low eccentricity orbits are some of the least detectable systems among our models. The dAGNs in models in which the accreting MBHs are allowed to exhibit radiative feedback are characterized by a significantly lower overall detectability. The suppression in detectability is most pronounced in gas-rich merger remnant galaxies, where radiation feedback is more likely to arise. If so, then large, relatively gas-poor galaxies may be the best candidates for detecting dAGNs.

Keywords: AGN host galaxies, Supermassive black holes, Galaxy mergers, Galaxy evolution, Dynamical friction
Outflow Bubbles from Compact Binary Mergers Embedded in Active Galactic Nuclei: Cavity Formation and the Impact on Electromagnetic Counterparts. We propose a novel scenario for possible electromagnetic (EM) emission by compact binary mergers in the accretion disks of active galactic nuclei (AGNs). Nuclear star clusters in AGNs are a plausible formation site of compact-stellar binaries (CSBs) whose coalescences can be detected through gravitational waves (GWs). We investigate the accretion onto and outflows from CSBs embedded in AGN disks. We show that these outflows are likely to create outflow cavities in the AGN disks before the binaries merge, which makes EM or neutrino counterparts much less common than would otherwise be expected. We discuss the necessary conditions for detectable EM counterparts to mergers inside the outflow cavities. If the merger remnant black hole experiences a high recoil velocity and can enter the AGN disk, it can accrete gas with a super-Eddington rate, newly forming a cavity-like structure. This bubble can break out of the disk within a day to a week after the merger. Such breakout emission can be bright enough to be detectable by current soft X-ray instruments, such as Swift-XRT and Chandra.

Keywords: Accretion, Transient sources, Stellar mass black holes, Active galactic nuclei, Gravitational waves
Dynamical Model of the Milky Way Using APOGEE and Gaia Data. We construct a dynamical model of the Milky Way disk from a data set that combines Gaia EDR3 and APOGEE data throughout galactocentric radii in the range 5.0 kpc ≤ R ≤ 19.5 kpc. We make use of the spherically aligned Jeans anisotropic method to model the stellar velocities and their velocity dispersions. Building upon our previous work, our model is now fitted to kinematic maps that have been extended to larger galactocentric radii due to the expansion of our data set, probing the outer regions of the Galactic disk. Our best-fitting dynamical model suggests a logarithmic density slope of αDM = -1.602 ± 0.079syst for the dark matter halo and a dark matter density of ρDM(R⊙) = (8.92 ± 0.56syst) × 10-3 M⊙ pc-3 (0.339 ± 0.022syst GeV cm3). We estimate a circular velocity at the solar radius of vcirc = (234.7 ± 1.7syst) km s-1 with a decline toward larger radii. The total mass density is ρtot(R⊙) = (0.0672 ± 0.0015syst) M⊙ pc-3 with a slope of αtot = -2.367 ± 0.047syst for 5 kpc ≤ R ≤ 19.5 kpc, and the total surface density is Σ(R⊙, ∣z∣ ≤ 1.1 kpc) = (55.5 ± 1.7syst) M⊙ pc-2. While the statistical errors are small, the error budget of the derived quantities is dominated by the three to seven times larger systematic uncertainties. These values are consistent with our previous determination, but the systematic uncertainties are reduced due to the extended data set covering a larger spatial extent of the Milky Way disk. Furthermore, we test the influence of nonaxisymmetric features on our resulting model and analyze how a flaring disk model would change our findings.

Keywords: Milky Way disk, Milky Way dynamics
Long Live the Disk: Lifetimes of Protoplanetary Disks in Hierarchical Triple-star Systems and a Possible Explanation for HD 98800 B. The gas dissipation from a protoplanetary disk is one of the key processes affecting planet formation, and it is widely accepted that it happens on timescales of a few million years for disks around single stars. In recent years, several protoplanetary disks have been discovered in multiple-star systems, and despite the complex environment in which they find themselves, some of them seem to be quite old, a situation that may favor planet formation. A clear example of this is the disk around HD 98800 B, a binary in a hierarchical quadruple stellar system, which at an ~10 Myr age seems to still be holding significant amounts of gas. Here we present a 1D+1D model to compute the vertical structure and gas evolution of circumbinary disks in hierarchical triple-star systems considering different stellar and disk parameters. We show that tidal torques due to the inner binary, together with the truncation of the disk due to the external companion, strongly reduce the viscous accretion and expansion of the disk. Even allowing viscous accretion by tidal streams, disks in these kind of environments can survive for more than 10 Myr, depending on their properties, with photoevaporation being the main gas dissipation mechanism. We particularly apply our model to the circumbinary disk around HD 98800 B and confirm that its longevity, along with the current nonexistence of a disk around the companion binary HD 98800 A, can be explained with our model and by this mechanism.

Keywords: Protoplanetary disks
Origins of the Long-term Variability of the Near-infrared Emission of the Black Hole X-Ray Binary GRS 1915+105 in the X-Ray Low Luminous State. Since 2018 July, the black hole X-ray binary GRS 1915+105 has been in an X-ray low luminous state (XLLS), which is the faintest period ever observed in a soft X-ray band. We present here the results of near-infrared (NIR) observations from 2019 April-December in the XLLS using HONIR attached to the Kanata telescope, together with radio data obtained by the Yamaguchi Interferometer and archival X-ray data. We found the historical NIR brightening in the XLLS. For several tens of days in the XLLS, NIR flux showed a positive correlation with radio flux and negative correlation with X-ray flux. This result suggests that at least a jet contributes to the NIR bands in the NIR-bright XLLS period. An accretion disk is not likely a candidate for the NIR emission because of the decrease of X-ray flux. In contrast to the NIR band, there was no historical radio brightening in the XLLS. This implies that the NIR emission in the NIR-bright period cannot be explained by the jet alone. The X-ray obscuration suggested by X-ray data is another possible candidate for the nonjet emission component in the NIR band.

Keywords: Low-mass x-ray binary stars, Black hole physics, Accretion, Near infrared astronomy
The Effect of Thermal Nonequilibrium on Helmet Streamers. Solar loops in which the coronal heating scale is short compared to the loop length are known to be susceptible to thermal nonequilibrium (TNE). We investigate the effects of this process on the largest loops in the corona, those of a helmet streamer. Our numerical study uses a 2.5D MHD code that includes the full magnetic field dynamics as well as the detailed plasma thermodynamics. The simulation model is axisymmetric, consisting of an equatorial streamer belt and two polar coronal holes. As in previous 1D loop studies, we find that TNE occurs in coronal loops with sufficiently large length, but in contrast to these studies, we find that the process also drives substantial magnetic dynamics, especially near the top of the streamer where the plasma beta becomes of order unity. From the simulation results we determine predictions for spectroscopic and imaging observations of both the hot and cool helmet streamer plasma. Simulations are preformed using different scale heights for the heating and different numerical resolution in order to determine the dependence of our findings on these important parameters. We conclude that TNE in streamers may explain several puzzling observations, such as the ubiquitous blueshifts observed at the edges of active regions. We also discuss the implications of our results for the solar wind.

Keywords: Magnetohydrodynamics, Solar coronal loops, Solar coronal heating, Solar physics, Solar corona, Solar magnetic fields, Solar coronal streamers
Modeling the Sgr A* Black Hole Immersed in a Dark Matter Spike. In this paper, we investigate the effects of a dark matter (DM) spike on the neighborhood of Sgr A*, the black hole (BH) in the center of the Milky Way. Our main goal is to investigate whether current and future astronomical observations of Sgr A* could detect the presence of such a DM spike. At first, we construct the spacetime metric around a static and spherically symmetric BH with a DM spike, and later, this solution is generalized for a rotating BH using the Newman-Janis-Azreg-Aïnou algorithm. For the static BH metric, we use the data of the S2 star orbiting Sgr A* to determine and analyze the constraints on the two free parameters characterizing the density and innermost boundary of the DM halo surrounding the BH. Furthermore, by making use of the available observational data for the DM spike density ρsp and the DM spike radius Rsp in the Milky Way, we consider a geometrically thick accretion disk model around the Sgr A* BH and demonstrate that the effect of DM distribution on the shadow radius and the image of the BH is considerably weak for realistic DM densities, becoming significant only when the DM density is of the order ρsp ~ (10-19-10-20) g cm-3 near the BH. We further analyze the possibility of observing this effect with radio interferometry, simulating observations with an EHT-like array, and find that it is unlikely to be detectable in the near future.

Keywords: Dark matter density, Milky Way dark matter halo, Supermassive black holes, Accretion
A Search for TeV Gamma-Ray Emission from Pulsar Tails by VERITAS. We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205, and PSR J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits with other pulsar wind nebulae detected in X-rays and the tail emission model predictions. We find that at least one of the three tails is likely to be detected in observations that are a factor of 2-3 more sensitive. The analysis presented here also has implications for deriving the properties of pulsar tails, for those pulsars whose tails could be detected in TeV.

Keywords: Gamma-rays, Pulsars
Recovering Density Fields inside Quasar Proximity Zones at z   6. The matter density field at z ~ 6 is very challenging to probe. One of the traditional probes of the low density intergalactic medium that works successfully at lower redshifts is the Lyα forest in quasar spectra. However, at the end of reionization, the residual neutral hydrogen usually creates saturated absorption, thus much of the information about the gas density is lost. Luckily, in a quasar proximity zone, the ionizing radiation is exceptionally intense, thus creating a large region with nonzero transmitted flux. In this study we use the synthetic spectra from simulations to investigate how to recover the density fluctuations inside the quasar proximity zones. We show that, under ideal conditions, the density can be recovered accurately with a small scatter. We also discuss how systematics such as the quasar continuum fitting and reionization models affect the results. This study shows that by analyzing the absorption features inside quasar proximity zones we can potentially constrain quasar properties and the environments they reside in.

Keywords: Cosmology, Large-scale structure of the universe, Quasars, Intergalactic medium, Reionization