Sazuna/UAT_keywords huggingface dataset:
Anisotropy of Magnetic Field and Velocity Fluctuations in the Solar Wind. We present a large statistical study of the fluctuation anisotropy in minimum variance (MV) frames of the magnetic field and solar wind velocity. We use 2, 10, 20, and 40 minute intervals of simultaneous magnetic field (the Wind spacecraft) and velocity (the Spektr-R spacecraft) observations. Our study confirms that magnetic turbulence is a composite of fluctuations varying along the mean magnetic field and those changing in the direction perpendicular to the mean field. Regardless of the length scale within the studied range of spacecraft-frame frequencies, 90 of the observed magnetic field fluctuations exhibit an MV direction aligned with the mean magnetic field, 10 of events have the MV direction perpendicular to the background field, and a negligible portion of fluctuations has no preferential direction. On the other hand, the MV direction of velocity fluctuations tends to be distributed more uniformly. An analysis of magnetic compressibility and density fluctuations suggests that the fluctuations resemble properties of Alfvnic fluctuations if the MV direction is aligned with background magnetic field whereas slow-mode-like fluctuations have the MV direction perpendicular to the background field. The proportion between Alfvnic and slow-mode-like fluctuations depends on plasma and length scale: the dependence on the solar wind speed is weak. We present 3D numerical MHD simulations and show that the numerical results are compatible with our experimental results.

Keywords: Slow solar wind, Heliosphere, Fast solar wind, Interplanetary turbulence, Solar wind, Alfven waves
The Effect of the Morphological Quenching Mechanism on Star Formation Activity at 0.5 &lt; z &lt; 1.5 in 3D-HST/CANDELS. Several mechanisms for the transformation of blue star-forming to red quiescent galaxies have been proposed, and the green valley (GV) galaxies amid them are widely accepted in a transitional phase. Thus, comparing the morphological and environmental differences of the GV galaxies with early-type disks (ETDs; bulge dominated and having a disk) and late-type disks (LTDs; disk dominated) is suitable for distinguishing the corresponding quenching mechanisms. A large population of massive (M* ≥ 1010 M⊙) GV galaxies at 0.5 ≤ z ≤ 1.5 in 3D-HST/CANDELS is selected using extinction-corrected (U-V)rest color. After eliminating any possible active galactic nucleus candidates and considering the "mass-matching," we finally construct two comparable samples of GV galaxies with either 319 ETD or 319 LTD galaxies. Compared to the LTD galaxies, it is found that the ETD galaxies possess higher concentration index and lower specific star formation rate, whereas the environments surrounding them are not different. This may suggest that the morphological quenching may dominate the star formation activity of massive GV galaxies rather than the environmental quenching. To quantify the correlation between the galaxy morphology and the star formation activity, we define a dimensionless morphology quenching efficiency Qmor and find that Qmor is not sensitive to the stellar mass and redshift. When the difference between the average star formation rate of ETD and LTD galaxies is about 0.7 M⊙ yr-1, the probability of Qmor ≳ 0.2 is higher than 90%, which implies that the degree of morphological quenching in GV galaxies might be described by Qmor ≳ 0.2.

Keywords: Galaxy structure, Star formation, Galaxy evolution, High-redshift galaxies, Galaxies
Deep Observations of CO and Free-Free Emission in Ultraluminous Infrared QSO IRAS F07599+6508. Infrared quasi-stellar objects (IR QSOs) are a rare subpopulation selected from ultraluminous infrared galaxies (ULIRGs) and have been regarded as promising candidates of ULIRG-to-optical QSO transition objects. Here we present NOEMA observations of the CO (1-0) line and 3 mm continuum emission in IR QSO IRAS F07599+6508 at z = 0.1486, which has many properties in common with Mrk 231. The CO emission is found to be resolved with a major axis of ∼6.1 kpc that is larger than the size of ∼4.0 kpc derived for 3 mm continuum. We identify two faint CO features located at a projected distance of ∼11.4 and 19.1 kpc from the galaxy nucleus, both of which are found to have counterparts in the optical and radio bands and may have a merger origin. A systematic velocity gradient is found in the CO main component, suggesting that the bulk of molecular gas is likely rotationally supported. Based on the radio-to-millimeter spectral energy distribution and IR data, we estimate that about 30% of the flux at 3 mm arises from free-free emission and infer a free-free-derived star formation rate of 77 M⊙ yr-1, close to the IR estimate corrected for the AGN contribution. We find a high-velocity CO emission feature at the velocity range of about -1300 to -2000 km s-1. Additional deep CO observations are needed to confirm the presence of a possible very high velocity CO extension of the OH outflow in this IR QSO.

Keywords: AGN host galaxies, Starburst galaxies, Interstellar molecules, Galaxy evolution, Galaxy mergers
Machine-learning Application to Fermi-LAT Data: Sharpening All-sky Map and Emphasizing Variable Sources. A novel application of machine-learning (ML) based image processing algorithms is proposed to analyze an all-sky map (ASM) obtained using the Fermi Gamma-ray Space Telescope. An attempt was made to simulate a 1 yr ASM from a short-exposure ASM generated from 1-week observation by applying three ML-based image processing algorithms: dictionary learning, U-net, and Noise2Noise. Although the inference based on ML is less clear compared to standard likelihood analysis, the quality of the ASM was generally improved. In particular, the complicated diffuse emission associated with the galactic plane was successfully reproduced only from 1-week observation data to mimic a ground truth (GT) generated from a 1 yr observation. Such ML algorithms can be implemented relatively easily to provide sharper images without various assumptions of emission models. In contrast, large deviations between simulated ML maps and the GT map were found, which are attributed to the significant temporal variability of blazar-type active galactic nuclei (AGNs) over a year. Thus, the proposed ML methods are viable not only to improve the image quality of an ASM but also to detect variable sources, such as AGNs, algorithmically, i.e., without human bias. Moreover, we argue that this approach is widely applicable to ASMs obtained by various other missions; thus, it has the potential to examine giant structures and transient events, both of which are rarely found in pointing observations.

Keywords: Gamma-ray astronomy, Astronomy data analysis, Astronomical simulations
A Focused Transport-based Kinetic Fractional Diffusion-advection Equation for Energetic Particle Trapping and Reconnection-related Acceleration by Small-scale Magnetic Flux Ropes in the Solar Wind. Analysis of energetic particle inner heliospheric spacecraft data increasingly suggests the existence of anomalous diffusion phenomena that should be addressed to achieve a better understanding of energetic particle transport and acceleration in the expanding solar wind medium. Related to this is fast-growing observational evidence supporting the long-standing prediction from magnetohydrodynamic (MHD) theory and simulations of the presence of an inner heliospheric, dominant quasi-two-dimensional MHD turbulence component that contains coherent contracting and merging (reconnecting) small-scale magnetic flux rope (SMFR) structures. This suggests that energetic particle trapping in SMFRs should play a role in anomalous diffusion in the solar wind that warrants further investigation. However, progress in studying such anomalous energetic particle transport phenomena in the solar wind is hampered by the lack of a fundamental derivation of a general fractional kinetic transport equation linking macroscopic energetic particle fractional transport to the microscopic physics of energetic particle interaction with SMFR structures. Here, we outline details of how one can derive a closed ensemble-averaged focused transport equation in the form of a general kinetic fractional diffusion-advection equation from first principles following the nonlinear Eulerian correlation function closure approach of Sanchez et al. With this equation one can model the anomalous diffusion of energetic particles in ordinary, momentum, and pitch-angle space in response to particle trapping in numerous SMFRs advected with the solar wind flow.

Keywords: Interplanetary particle acceleration, Solar wind, Solar magnetic reconnection
The JCMT BISTRO Survey: The Distribution of Magnetic Field Strengths toward the OMC-1 Region. Measurement of magnetic field strengths in a molecular cloud is essential for determining the criticality of magnetic support against gravitational collapse. In this paper, as part of the JCMT BISTRO survey, we suggest a new application of the Davis-Chandrasekhar-Fermi (DCF) method to estimate the distribution of magnetic field strengths in the OMC-1 region. We use observations of dust polarization emission at 450 and 850 μm, and C18O (3-2) spectral line data obtained with the JCMT. We estimate the volume density, the velocity dispersion, and the polarization angle dispersion in a box, 40″ × 40″ (5×5 pixels), which moves over the OMC-1 region. By substituting three quantities in each box with the DCF method, we get magnetic field strengths over the OMC-1 region. We note that there are very large uncertainties in the inferred field strengths, as discussed in detail in this paper. The field strengths vary from 0.8 to 26.4 mG, and their mean value is about 6 mG. Additionally, we obtain maps of the mass-to-flux ratio in units of a critical value and the Alfvén Mach number. The central parts of the BN-KL and South (S) clumps in the OMC-1 region are magnetically supercritical, so the magnetic field cannot support the clumps against gravitational collapse. However, the outer parts of the region are magnetically subcritical. The mean Alfvén Mach number is about 0.4 over the region, which implies that the magnetic pressure exceeds the turbulent pressure in the OMC-1 region.

Keywords: Interstellar magnetic fields, Star forming regions, Polarimetry, Dense interstellar clouds
Do All Long-duration Gamma-Ray Bursts Emit GeV Photons?. GRB 190114C extends the focus of gamma-ray burst (GRB) research to the high-energy regime, in which a prime question is "Do all long-duration GRBs emit GeV photons?" Based on the Fermi Large Area Telescope (LAT) 10 yr observations, 54 GRBs initially within the Fermi-LAT field of view and with known redshift are sampled. Within 26 of these GRBs at least one GeV photon has been detected with a probability of &gt;95%, while the other 28 GRBs have no confident GeV photon detection. We hypothesize that all the samples intrinsically emit GeV photons, and the lack of detection is due to the limited capacity of the satellite. We estimate the theoretical number of photons that LAT receives by considering the GRB energy, the distance, and the LAT effective area. Results show, within the uncertainty, that all 26 GRBs with GeV photon detection have a theoretical photon number of &gt;1, and 27 out of 28 GRBs without GeV photon detection have a theoretical photon number of &lt;1. This agreement tends to support our hypothesis and give an answer of "yes" to our initial question.

Keywords: Gamma-ray bursters, High energy astrophysics, Astronomical instrumentation
Analysis of Time-Distance Helioseismology for Detection of Emerging Active Regions. A time-distance helioseismic technique, similar to the one used by Ilonidis et al., is applied to two independent numerical models of subsurface sound-speed perturbations to determine the spatial resolution and accuracy of phase travel time shift measurements. The technique is also used to examine pre-emergence signatures of several active regions observed by the Michelson Doppler Imager and the Helioseismic Magnetic Imager. In the context of similar measurements of quiet-Sun regions, three of the five studied active regions show strong phase travel time shifts several hours prior to emergence. These results form the basis of a discussion of noise in the derived phase travel time maps and possible criteria to distinguish between true and false-positive detection of emerging flux.

Keywords: Helioseismology, Solar active regions, Solar magnetic flux emergence
The Thermal Sunyaev-Zel'dovich Effect from Massive, Quiescent 0.5 ≤ z ≤ 1.5 Galaxies. We use combined South Pole Telescope (SPT)+Planck temperature maps to analyze the circumgalactic medium (CGM) encompassing 138,235 massive, quiescent 0.5 ≤ z ≤ 1.5 galaxies selected from data from the Dark Energy Survey (DES) and Wide-Field Infrared Survey Explorer (WISE). Images centered on these galaxies were cut from the 1.85 arcmin resolution maps with frequency bands at 95, 150, and 220 GHz. The images were stacked, filtered, and fit with a graybody dust model to isolate the thermal Sunyaev-Zel'dovich (tSZ) signal, which is proportional to the total energy contained in the CGM of the galaxies. We separated these M⋆ = 1010.9M⊙-1012M⊙ galaxies into 0.1 dex stellar mass bins, detecting tSZ per bin up to 5.6σ and a total signal-to-noise ratio of 10.1σ. We also detect dust with an overall signal-to-noise ratio of 9.8σ, which overwhelms the tSZ at 150 GHz more than in other lower-redshift studies. We corrected for the 0.16 dex uncertainty in the stellar mass measurements by parameter fitting for an unconvolved power-law energy-mass relation, ${E}_{\mathrm{therm}}={E}_{\mathrm{therm},\mathrm{peak}}{\left({M}_{\star }/{M}_{\star ,\mathrm{peak}}\right)}^{\alpha }$ , with the peak stellar mass distribution of our selected galaxies defined as M⋆,peak = 2.3 × 1011M⊙. This yields an ${E}_{\mathrm{therm},\mathrm{peak}}={5.98}_{-1.00}^{+1.02}\,\times {10}^{60}$ erg and $\alpha ={3.77}_{-0.74}^{+0.60}$ . These are consistent with z ≈ 0 observations and within the limits of moderate models of active galactic nucleus feedback. We also computed the radial profile of our full sample, which is similar to that recently measured at lower-redshift by Schaan et al.

Keywords: Large-scale structure of the universe, Quasars, Sunyaev-Zeldovich effect, Galaxy evolution, Intergalactic medium, Cosmic background radiation
Solar Energetic Electron Events Associated with Hard X-Ray Flares. We investigate 16 solar energetic electron (SEE) events measured by WIND/3DP with a double-power-law spectrum and the associated western hard X-ray (HXR) flares measured by RHESSI with good count statistics, from 2002 February to 2016 December. In all the 16 cases, the presence of an SEE power-law spectrum extending down to ≤5 keV at 1 au implies that the SEE source would be high in the corona, at a heliocentric distance of ≥1.3 solar radii, while the footpoint or footpoint-like emissions shown in HXR images suggest that the observed HXRs are likely produced mainly by HXR-producing electrons via thick-target bremsstrahlung processes very low in the corona. We find that for all the 16 cases, the estimated power-law spectral index of HXR-producing electrons is no less than the observed high-energy spectral index of SEEs, and it shows a positive correlation with the high-energy spectral index of SEEs. In addition, the estimated number of SEEs is only ∼10-4-10-2 of the estimated number of HXR-producing electrons at energies above 30 keV, but with a positive correlation between the two numbers. These results suggest that in these cases, SEEs are likely formed by upward-traveling electrons from an acceleration source high in the corona, while their downward-traveling counterparts may undergo a secondary acceleration before producing HXRs via thick-target bremsstrahlung processes. In addition, the associated 3He/4He ratio is positively correlated with the observed high-energy spectral index of SEEs, indicating a possible relation of the 3He ion acceleration with high-energy SEEs.

Keywords: Solar energetic particles, Solar flares
TEM Analyses of Unusual Presolar Silicon Carbide: Insights into the Range of Circumstellar Dust Condensation Conditions. Presolar silicon carbide (SiC) grains in meteoritic samples can help constrain circumstellar condensation processes and conditions in C-rich stars and core-collapse supernovae (CCSNe). This study presents our findings on eight presolar SiC grains from asymptotic giant branch (AGB) stars (four mainstream and one Y grain) and CCSNe (three X grains), chosen on the basis of μ-Raman spectral features that were indicative of their having unusual non-3C polytypes and/or high degrees of crystal disorder. Analytical transmission electron microscopy (TEM), which provides elemental compositional and structural information, shows evidence for complex histories for the grains. Our TEM results confirm the presence of non-3C,2H crystal domains. Minor-element heterogeneities and/or subgrains were observed in all grains analyzed for their compositions. The C/O ratios inferred for the parent stars varied from 0.98 to ≥1.03. Our data show that SiC condensation can occur under a wide range of conditions, in which environmental factors other than temperature (e.g., pressure, gas composition, heterogeneous nucleation on precondensed phases) play a significant role. Based on previous μ-Raman studies, ∼10% of SiC grains may have infrared (IR) spectral features that are influenced by crystal defects, porosity, and/or subgrains. Future sub-diffraction-limited IR measurements of complex SiC grains might shed further light on the relative contributions of each of these features to the shape and position of the characteristic IR 11 μm SiC feature and thus improve the interpretation of IR spectra of AGB stars like those that produced the presolar SiC grains.

Keywords: Asymptotic giant branch stars, Circumstellar dust, Chemical abundances, Core-collapse supernovae
Shaping "Ears" in Planetary Nebulae by Early Jets. We conduct three-dimensional hydrodynamical numerical simulations of planetary nebula (PN) shaping and show that jets that precede the ejection of the main PN shell can form the morphological feature of ears. Ears are two opposite protrusions from the main nebula that are smaller than the main nebula and with a cross section that decreases monotonically from the base of an ear at the shell to its far end. Only a very small fraction of PNe have ears. The short-lived jets, about a year in the present simulations, interact with the regular asymptotic giant branch wind to form the ears, while the later blown dense wind forms the main PN dense shell. Namely, the jets are older than the main PN shell. We also find that for the jets to inflate ears they cannot be too energetic, cannot be too wide, and cannot be too slow. A flow structure where short-lived jets precede the main phase of nebula ejection by a few years or less can result from a system that enters a common envelope evolution. The low mass companion accretes mass through an accretion disk and launches jets just before it enters the envelope of the giant progenitor star of the PN. Shortly after that the companion enters the envelope and spirals-in to eject the envelope that forms the main PN shell.

Keywords: Close binary stars, Stellar jets, Planetary nebulae
Pebble Trapping in Vortices: Three-dimensional Simulations. Disk vortices have been heralded as promising routes for planet formation due to their ability to trap significant amounts of pebbles. While the gas motions and trapping properties of two-dimensional vortices have been studied in enough detail in the literature, pebble trapping in three dimensions has received less attention, due to the higher computational demand. Here we use the Pencil Code to study 3D vortices generated by convective overstability and the trapping of solids within them. The gas is unstratified whereas the pebbles settle to the midplane due to vertical gravity. We find that for pebbles of normalized friction times of $\mathrm{St}=0.05$ and $\mathrm{St}=1$ , and dust-to-gas ratio $\varepsilon =0.01$ , the vortex column in the midplane is strongly perturbed. Yet when the initial dust-to-gas ratio is decreased the vortices remain stable and function as efficient pebble traps. Streaming instability is triggered even for the lowest dust-to-gas ratio ( ${\varepsilon }_{0}={10}^{-4}$ ) and smallest pebble sizes ( $\mathrm{St}=0.05$ ) we assumed, showing a path for planetesimal formation in vortex cores from even extremely subsolar metallicity. To estimate if the reached overdensities can be held together solely by their own gravity we estimate the Roche density at different radii. Depending on disk model and radial location of the pebble clump we do reach concentrations higher than the Roche density. We infer that if self-gravity was included for the pebbles then gravitational collapse would likely occur.

Keywords: Solar nebulae, Solar system formation, Planetary system formation, Circumstellar matter, Protoplanetary disks, Circumstellar disks, Circumstellar dust, Planet formation
The Powers of Relativistic Jets Depend on the Spin of Accreting Supermassive Black Holes. Theoretical models show that the power of relativistic jets of active galactic nuclei depends on the spin and mass of the central supermassive black holes, as well as the accretion. Here we report an analysis of archival observations of a sample of blazars. We find a significant correlation between jet kinetic power and the spin of supermassive black holes. At the same time, we use multiple linear regression to analyze the relationship between jet kinetic power and accretion, spin, and black hole mass. We find that the spin of supermassive black holes and accretion are the most important contributions to the jet kinetic power. The contribution rates of both the spin of supermassive black holes and accretion are more than 95%. These results suggest that the spin energy of supermassive black holes powers the relativistic jets. The jet production efficiency of almost all Fermi blazars can be explained by moderately thin, magnetically arrested accretion disks around rapidly spinning black holes.

Keywords: Blazars, Active galactic nuclei
The Circumnuclear Disk Revealed by ALMA. I. Dense Clouds and Tides in the Galactic Center. Utilizing the Atacama Large Millimeter/submillimeter Array, we present CS line maps in five rotational lines (Ju = 7, 5, 4, 3, 2) toward the circumnuclear disk (CND) and streamers of the Galactic center. Our primary goal is to resolve the compact structures within the CND and the streamers, in order to understand the stability conditions of molecular cores in the vicinity of the supermassive black hole (SMBH) Sgr A*. Our data provide the first homogeneous high-resolution (1"3 = 0.05 pc) observations aiming at resolving density and temperature structures. The CS clouds have sizes of 0.05-0.2 pc with a broad range of velocity dispersion (σFWHM = 5-40 km s-1). The CS clouds are a mixture of warm (Tk ≥ 50-500 K, ${n}_{{{\rm{H}}}_{2}}$ = 103-105 cm-3) and cold gas (Tk ≤ 50 K, ${n}_{{{\rm{H}}}_{2}}$ = 106-108 cm-3). A stability analysis based on the unmagnetized virial theorem including tidal force shows that ${84}_{-37}^{+16} \% $ of the total gas mass is tidally stable, which accounts for the majority of gas mass. Turbulence dominates the internal energy and thereby sets the threshold densities 10-100 times higher than the tidal limit at distance ≥1.5 pc to Sgr A*, and therefore it inhibits the clouds from collapsing to form stars near the SMBH. However, within the central 1 pc, the tidal force overrides turbulence and the threshold densities for a gravitational collapse quickly grow to ≥ 108 cm-3.

Keywords: Interstellar molecules, Galactic center, Radio interferometers