Sazuna/UAT_keywords huggingface dataset:
Shock Heating of Directly Transmitted Ions. Collisionless shock heats ions very efficiently. Ion heating is a nonadiabatic process and the downstream temperature is not proportional to the upstream temperature. Ion distributions just behind the shock transition are gyrophase dependent and gradually gyrotropize. With the increase of the Mach number the contribution of reflected ions into ion heating gradually increases. Yet, directly transmitted ions may remain responsible for most of the downstream temperature. Direct transmission allows analytical treatment within the approximation of a narrow shock. We determine the gyrophase-dependent distribution just behind the magnetic jump, the gyrotropic distribution farther behind the shock, and establish the relation with the magnetic compression and the maximum overshoot magnetic field.

Keywords: Shocks, Interplanetary shocks, Planetary bow shocks
The Transport Equation for the Dispersal of Passive Tracers in a Nonuniform Turbulent Fluid: Numerical Simulations. The random advection of passive additives in a turbulent fluid plays an important role in solar physics, astrophysics, and atmospheric sciences. We concern ourselves here with the case where the fluctuations are not statistically homogeneous in space, and, hence, where the transport coefficients vary with position. Using a numerical model in which the fluid turbulence is defined kinematically, we show that the evolution of the distribution of passive tracers in the fluid is not always governed by the ordinary diffusion equation. We find it is governed by a more general transport equation whose form depends on the nature of the turbulence, particularly on its compressibility, or divergence. The more general transport equation resembles the ordinary diffusion equation, but the transport coefficient appears in two places and is raised to a power that depends on the divergence of the fluid velocity. If the flow has zero divergence, the case for incompressible turbulence, the resulting transport equation is found to be the regular diffusion equation.

Keywords: Hydrodynamics, Plasma astrophysics, Solar magnetic fields, Astrophysical fluid dynamics, Atmospheric science
Energy Supply by Low-frequency Break Sweeping for Heating the Fast Solar Wind from 0.3 to 4.8 au. Solar wind protons undergo significant heating during the expansion of the solar wind and turbulence plays an important role in this process. It is believed that the energy is injected from the energy-containing range into the inertial range and then transferred to dissipate into heat eventually. However, the energy injection process in the heliosphere remains unclear. Here we analyze this process. We utilize Helios 2 and Ulysses measurements of the fast solar wind at different radial distances from 0.29 to 4.8 au. We obtain the perpendicular heating rate based on the gradient of the magnetic moment. We estimate for the first time the energy supply rate due to the sweeping of low-frequency break based on the identification of low-frequency break and the corresponding power spectra density profile. We find that the energy supply rate is comparable to the perpendicular heating rate of protons, which support the idea that low-frequency range becomes part of the inertial range as the solar wind turbulence ages. These results help us understand the energy supply process from the energy-containing range and the heating process of solar wind protons.

Keywords: Interplanetary turbulence, Solar coronal heating, Fast solar wind
Interplanetary Shock Candidates Observed at Venus's Orbit. The measurements from the Venus Express spacecraft are analyzed for the basic properties of fast forward interplanetary shocks at Venus's orbit (∼0.72 au). A total of 143 fast forward interplanetary shock candidates during 2006-2014 are identified. The shock angle ΘBn, defined as the angle between the shock normal and the upstream magnetic field, and the magnetic compression ratio rB, defined as the ratio of the magnetic field strength downstream to that upstream, of these shocks are determined based on the magnetic coplanarity method. The shock occurrence at Venus shows a correlated variation with the solar activity level measured by the number of sunspots, while the shock angle and magnetic compression ratio do not show such a correspondence. The shock angle spreads almost uniformly between 10° and 80° with its mean value at about 45°, and the magnetic compression ratio shows a unimodal distribution between 1.0 and 4.5 with a mean value of 2.1. In addition, we also analyze the properties of fast forward shocks driven by interplanetary coronal mass ejections (ICMEs). We found that interplanetary shocks with and without detected ICMEs showed no significant differences in terms of the shock strength and the shock angle. Further comparison with previous observational results at 1 au shows that fast forward shocks at 1 au are generally weaker than those at 0.72 au, and the shock angle ΘBn is more perpendicular at 1 au.

Keywords: Interplanetary shocks, Venus, Solar system terrestrial planets
Modeling Magnetic Disk Wind State Transitions in Black Hole X-Ray Binaries. We analyze three prototypical black hole X-ray binaries, 4U 1630-472, GRO J1655-40, and H1743-322, in an effort to systematically understand the intrinsic state transition of the observed accretion disk winds between wind-on and wind-off states by utilizing state-of-the-art Chandra/HETGS archival data from multi-epoch observations. We apply our magnetically driven wind models in the context of magnetohydrodynamic (MHD) calculations to constrain (1) their global density slope (p), (2) their density (n17) at the foot point of the innermost launching radius, and (3) the abundances of heavier elements (AFe,S,Si). Incorporating the MHD winds into xstar photoionization calculations in a self-consistent manner, we create a library of synthetic absorption spectra given the observed X-ray continua. Our analysis clearly indicates a characteristic bimodal transition of multi-ion X-ray winds; i.e., the wind density gradient is found to steepen (from p ∼ 1.2-1.4 to ∼1.4-1.5) while its density normalization declines as the source transitions from the wind-on to the wind-off state. The model implies that the ionized wind remains physically present even in the wind-off state, despite its apparent absence in the observed spectra. Supersolar abundances for heavier elements are also favored. Our global multi-ion wind models, taking into account soft X-ray ions as well as Fe K absorbers, show that the internal wind condition plays an important role in wind transitions besides photoionization changes. Simulated XRISM/Resolve and Athena/X-IFU spectra are presented to demonstrate a high fidelity of the multi-ion wind model for a better understanding of these powerful ionized winds in the coming decades.

Keywords: Accretion, Black hole physics, Radiative magnetohydrodynamics, Theoretical models, Compact binary stars, X-ray observatories, Spectroscopy, Low-mass x-ray binary stars
The HST See Change Program. I. Survey Design, Pipeline, and Supernova Discoveries. The See Change survey was designed to make z &gt; 1 cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass measurements through weak lensing. This survey observed twelve galaxy clusters with the Hubble Space Telescope (HST) spanning the redshift range z = 1.13-1.75, discovering 57 likely transients and 27 likely SNe Ia at z ∼ 0.8-2.3. As in similar previous surveys, this proved to be a highly efficient use of HST for supernova observations; the See Change survey additionally tested the feasibility of maintaining, or further increasing, the efficiency at yet higher redshifts, where we have less detailed information on the expected cluster masses and star formation rates. We find that the resulting number of SNe Ia per orbit is a factor of ∼8 higher than for a field search, and 45% of our orbits contained an active SN Ia within 22 rest-frame days of peak, with one of the clusters by itself yielding 6 of the SNe Ia. We present the survey design, pipeline, and supernova discoveries. Novel features include fully blinded supernova searches, the first random forest candidate classifier for undersampled IR data (with a 50% detection threshold within 0.05 mag of human searchers), real-time forward-modeling photometry of candidates, and semi-automated photometric classifications and follow-up forecasts. We also describe the spectroscopic follow-up, instrumental in measuring host galaxy redshifts. The cosmology analysis of our sample will be presented in a companion paper. * Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under programs 13677, 14327.

Keywords: Observational cosmology, Type Ia supernovae
Extended X-Ray Emission Associated with the Radio Lobes and the Environments of 60 Radio Galaxies. This paper studied the faint, diffuse extended X-ray emission associated with the radio lobes and the hot gas in the intracluster medium (ICM) environment for a sample of radio galaxies. We used shallow (∼10 ks) archival Chandra observations for 60 radio galaxies (7 FR I and 53 FR II) with 0.0222 ≤ z ≤ 1.785 selected from the 298 extragalactic radio sources identified in the 3CR catalog. We used Bayesian statistics to look for any asymmetry in the extended X-ray emission between regions that contain the radio lobes and regions that contain the hot gas in the ICM. In the Chandra broad band (0.5-7.0 keV), which has the highest detected X-ray flux and the highest signal-to-noise ratio, we found that the nonthermal X-ray emission from the radio lobes dominates the thermal X-ray emission from the environment for ∼77% of the sources in our sample. We also found that the relative amount of on-jet axis nonthermal emission from the radio lobes tends to increase with redshift compared to the off-jet axis thermal emission from the environment. This suggests that the dominant X-ray mechanism for the nonthermal X-ray emission in the radio lobes is due to the inverse Compton upscattering of cosmic microwave background (CMB) seed photons by relativistic electrons in the radio lobes, a process for which the observed flux is roughly redshift independent due to the increasing CMB energy density with increasing redshift.

Keywords: Radio hot spots, Radio cores, Radio source catalogs, Radio jets, Active galaxies, Radio lobes, Radio galaxies, X-ray quasars, Fanaroff-Riley radio galaxies, X-ray active galactic nuclei, Active galactic nuclei, Radio active galactic nuclei
Clumpy Star Formation and AGN Activity in the Dwarf-Dwarf Galaxy Merger Mrk 709. Nearby, low-metallicity dwarf starburst galaxies hosting active galactic nuclei (AGNs) offer the best local analogs to study the early evolution of galaxies and their supermassive black holes (BHs). Here we present a detailed multiwavelength investigation of star formation and BH activity in the low-metallicity dwarf-dwarf galaxy merger Mrk 709. Using Hubble Space Telescope Hα and continuum imaging combined with Keck spectroscopy, we determine that the two dwarf galaxies are likely in the early stages of a merger (i.e., their first pass) and discover a spectacular ∼10 kpc long string of young massive star clusters (t ≲ 10 Myr; M⋆ ≳ 105 M⊙) between the galaxies triggered by the interaction. We find that the southern galaxy, Mrk 709 S, is undergoing a clumpy mode of star formation resembling that seen in high-redshift galaxies, with multiple young clusters/clumps having stellar masses between 107 and 108 M⊙. Furthermore, we present additional evidence for a low-luminosity AGN in Mrk 709 S (first identified by Reines et al. using radio and X-ray observations), including the detection of the coronal [Fe X] optical emission line. The work presented here provides a unique glimpse into processes key to hierarchical galaxy formation and BH growth in the early universe.

Keywords: Dwarf irregular galaxies, Blue compact dwarf galaxies, Young massive clusters, Dwarf galaxies, Low-luminosity active galactic nuclei, Active galactic nuclei, Galaxy mergers, Interacting galaxies, Star clusters
Facilitating Interstellar Searches for Simple Amino Alcohols with Accurate Rest Frequencies into the Millimeter-wave Regime: Alaninol, Valinol, and Leucinol. The detection of larger complex organic molecules, such as molecules consisting of several functional groups or those which show conformational flexibility, in the interstellar medium could lead to insights into the availability of biomolecules in space. We present the rotational spectroscopic study of three amino alcohols: alaninol, valinol, and leucinol. The spectra were recorded over the 2-110 GHz region, which included the utilization of a newly developed instrument operating between 18-26 GHz. We report accurately determined line lists, rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants for two conformers of alaninol, four conformers of valinol, and three conformers of leucinol, as well as for several singly substituted heavy-atom isotopologues, which also provide structural insights. Further, a number of spectra of vibrationally excited states were assigned, and the associated motions were revealed with anharmonic frequency calculations. Accurate predictions of rotational transitions into the millimeter-wave regime for all species were made, facilitating searches for these complex molecules by observational facilities such as ALMA. Their detection would establish a new family of interstellar molecules.

Keywords: High resolution spectroscopy, Interstellar molecules, Spectral line lists, Molecular spectroscopy, Interstellar medium, Pre-biotic astrochemistry
How Does the Polar Dust Affect the Correlation between Dust Covering Factor and Eddington Ratio in Type 1 Quasars Selected from the Sloan Digital Sky Survey Data Release 16?. We revisit the dependence of the covering factor (CF) of dust torus on physical properties of active galactic nuclei (AGNs) by taking into account an AGN polar dust emission. The CF is converted from a ratio of infrared (IR) luminosity contributed from AGN dust torus ( ${L}_{\mathrm{IR}}^{\mathrm{torus}}$ ) and AGN bolometric luminosity (Lbol), by assuming a nonlinear relation between luminosity ratio and intrinsic CF. We select 37,181 type 1 quasars at z &lt; 0.7 from the Sloan Digital Sky Survey Data Release 16 quasar catalog. Their Lbol, black hole mass (MBH), and Eddington ratio (λEdd) are derived by spectral fitting with QSFit. We conduct spectral energy distribution decomposition by using X-CIGALE with a clumpy torus and polar dust model to estimate ${L}_{\mathrm{IR}}^{\mathrm{torus}}$ without being affected by the contribution of stellar and AGN polar dust to IR emission. For 5752 quasars whose physical quantities are securely determined, we perform a correlation analysis on CF and (i) Lbol, (ii) MBH, and (iii) λEdd. As a result, anticorrelations for CF-Lbol, CF-MBH, and CF-λEdd are confirmed. We find that incorporating the AGN polar dust emission makes those anticorrelations stronger compared to those without considering it. This indicates that polar dust wind probably driven by AGN radiative pressure is one of the key components to regulate obscuring material of AGNs.

Keywords: Supermassive black holes, Catalogs, Quasars
Velocity-resolved Reverberation Mapping of Changing-look AGN NGC 2617. NGC 2617 attracted a lot of attention after the detection of changes in its spectral type; the geometry and kinematics of the broad-line region (BLR) are still ambiguous. In this paper, we present the high cadence (∼2 days) reverberation mapping campaign of NGC 2617 from 2019 October to 2020 May undertaken at the Lijiang 2.4 m telescope. For the first time, the velocity-resolved reverberation signature of the object was successfully detected. Both Hα and Hβ show an asymmetrical profile with a peak in the velocity-resolved time lags. For both of the lines, the lag of the line core is longer than those of the relevant wings, and the peak of the velocity-resolved lags is slightly blueshifted. These characteristics are not consistent with the theoretical prediction of the inflow, outflow or Keplerian disk model. Our observations give the time lags of Hα, Hβ, Hγ, and He I, with a ratio of τHα: τHβ: τHγ: τHe I = 1.27:1.00:0.89:0.20, which indicates a stratified structure in the BLR of the object. It is the first time that the lags of Hα and He I are obtained. Assuming a virial factor of f = 5.5 for the dispersion width of the line, the masses of the black holes derived from Hα and Hβ are ${23.8}_{-2.7}^{+5.4}$ and ${21.1}_{-4.4}^{+3.8}\times {10}^{6}{M}_{\odot }$ , respectively. Our observed results indicate the complexity of the BLR of NGC 2617.

Keywords: Supermassive black holes, Reverberation mapping, Active galaxies, Seyfert galaxies, Photometry, Spectroscopy
X-Ray AGB Stars in the 4XMM-DR9 Catalog: Further Evidence for Companions. Single AGB stars are not normally expected to be X-ray emitters due to the lack of a corona capable of powering a hot plasma. Therefore, the detection of X-ray emission in AGB stars by the ROSAT, Chandra, and XMM-Newton observatories has been interpreted as evidence for binarity. The number of X-ray-emitting AGB stars is, however, very small, and statistically sound conclusions shall be considered tentative. In this paper we aim at increasing the number of X-ray-emitting AGB stars and at providing a consistent analysis of their X-ray emission to be compared to their UV and optical properties. The XMM-Newton 4XMM-DR9 catalog has been searched for X-ray counterparts of various types of AGB stars: nearby (i.e., listed in Hipparcos), mass-losing, and S- and C-types. Seventeen X-ray counterparts of AGB stars have been found in the 4XMM-DR9. Nine of them have pointed XMM-Newton observations, whereas eight are genuine serendipitous discoveries. Together with the AGB stars detected by ROSAT, this increases the number of X-ray AGB stars to 26. Most of their X-ray spectra can be fit by the emission from an optically thin single-temperature thermal plasma with temperatures typically larger than 107 K. There is no obvious correlation between the X-ray and bolometric luminosity of these stars, but the X-ray luminosity generally increases with the amount of far-UV excess. The high temperature of some X-ray-emitting plasma in AGB stars and the correlation of their X-ray luminosity with the far-UV emission supports the origin of this X-ray emission from accretion disks around unseen companions.

Keywords: X-ray binary stars, Close binary stars, Asymptotic giant branch stars, Late-type giant stars, Symbiotic binary stars, Single x-ray stars
Correlation of the Sunspot Number and the Waiting-time Distribution of Solar Flares, Coronal Mass Ejections, and Solar Wind Switchback Events Observed with the Parker Solar Probe. Waiting-time distributions of solar flares and coronal mass ejections (CMEs) exhibit power-law-like distribution functions with slopes in the range of ατ ≈ 1.4-3.2, as observed in annual data sets during four solar cycles (1974-2012). We find a close correlation between the waiting-time power-law slope ατ and the sunspot number (SN), i.e., ατ = 1.38 + 0.01 × SN. The waiting-time distribution can be fitted with a Pareto-type function of the form N(τ) = N0 ${({\tau }_{0}+\tau )}^{-{\alpha }_{\tau }}$ , where the offset τ0 depends on the instrumental sensitivity, the detection threshold of events, and pulse pileup effects. The time-dependent power-law slope ατ(t) of waiting-time distributions depends only on the global solar magnetic flux (quantified by the sunspot number) or flaring rate, which is not predicted by self-organized criticality or magnetohydrodynamic turbulence models. Power-law slopes of ατ ≈ 1.2-1.6 were also found in solar wind switchback events, as observed with the Parker Solar Probe during the solar minimum, while steeper slopes are predicted during the solar maximum. We find that the annual variability of switchback events in the heliospheric solar wind and solar flare and CME rates (originating in the photosphere and lower corona) are highly correlated.

Keywords: Solar wind, Solar flares
GRB 180418A: A Possibly Short Gamma-Ray Burst with a Wide-angle Outflow in a Faint Host Galaxy. We present X-ray and multiband optical observations of the afterglow and host galaxy of GRB 180418A, discovered by Swift/BAT and Fermi/GBM. We present a reanalysis of the GBM and BAT data deriving durations of the prompt emission of T90 ≍ 2.56 and 1.90 s, respectively. Modeling the Fermi/GBM catalog of 1405 bursts (2008-2014) in the hardness-T90 plane, we obtain a probability of ≍60% that GRB 180418A is a short-hard burst. From a combination of Swift/XRT and Chandra observations, the X-ray afterglow is detected to ≍38.5 days after the burst and exhibits a single power-law decline with FX ∝ t-0.98. Late-time Gemini observations reveal a faint r ≍ 25.69 mag host galaxy at an angular offset of ≍0"16. At the likely redshift range of z ≍ 1-2.25, we find that the X-ray afterglow luminosity of GRB 180418A is intermediate between short and long gamma-ray bursts (GRBs) at all epochs during which there are contemporaneous data and that GRB 180418A lies closer to the Eγ,peak-Eγ,iso correlation for short GRBs. Modeling the multiwavelength afterglow with the standard synchrotron model, we derive the burst explosion properties and find a jet opening angle of θj ≳ 9°-14°. If GRB 180418A is a short GRB that originated from a neutron star merger, it has one of the brightest and longest-lived afterglows along with an extremely faint host galaxy. If, instead, the event is a long GRB that originated from a massive star collapse, it has among the lowest-luminosity afterglows and lies in a peculiar space in terms of the hardness-T90 and Eγ,peak-Eγ,iso planes.

Keywords: Gamma-ray bursts, Gamma-ray transient sources
Resolving the Hot Dust Disk of ESO323-G77. Infrared interferometry has led to a paradigm shift in our understanding of the dusty structure in the central parsecs of active galactic nuclei (AGNs). The dust is now thought to comprise a hot (∼1000 K) equatorial disk, some of which is blown into a cooler (∼300 K) polar dusty wind by radiation pressure. In this paper, we utilize the new near-IR interferometer GRAVITY on the Very Large Telescope Interferometer (VLTI) to study a Type 1.2 AGNs hosted in the nearby Seyfert galaxy ESO 323-G77. By modeling the squared visibility and closure phase, we find that the hot dust is equatorially extended, consistent with the idea of a disk, and shows signs of asymmetry in the same direction. Furthermore, the data is fully consistent with the hot dust size determined by K-band reverberation mapping as well as the predicted size from a CAT3D-WIND model created in previous work using the spectral energy distribution of ESO 323-G77 and observations in the mid-IR from VLTI/MID-infrared Interferometric instrument).

Keywords: Optical interferometry, Astronomy data modeling, Infrared astronomy, Long baseline interferometry, Active galactic nuclei, Near infrared astronomy