Sazuna/UAT_keywords huggingface dataset:
Compressible and Incompressible Magnetic Turbulence Observed in the Very Local Interstellar Medium by Voyager 1. Voyager 1 observed Kolmogorov-like (k -5/3) compressible turbulence just upwind of the heliopause. Subsequent measurements by Voyager 1 further from the heliopause revealed that the observed fluctuations were now fully incompressible, with a k -5/3 spectrum that was essentially identical to that of the earlier compressible spectrum. Zank et al. showed that only compressible fast magnetosonic modes could be transmitted from the inner heliosheath into the very local interstellar medium (VLISM), and could exhibit a k -5/3 spectrum. We show here that the small plasma beta VLISM admits three-wave interactions between a fast magnetosonic mode, a zero-frequency mode, and an Alfvén wave. The fast magnetosonic mode is converted to an incompressible Alfvén (or zero-frequency) mode with wavenumber almost identical to that of the initial compressible fast mode. The initial compressible and generated incompressible spectra are essentially identical. For the wavelength range observed by Voyager 1, we estimate that compressible fast modes are fully mode-converted to incompressible fluctuations within ∼10 au of the heliopause. We suggest that the VLISM magnetic field spectrum is a superposition of a higher amplitude ∼k -5/3 spectrum of heliospheric origin with an estimated correlation length ∼30 au, having a minimum wavenumber ∼(100)-1 (au)-1, and a lower amplitude (possibly local) ISM k -5/3 spectrum, the latter possessing an outer scale ≥2 pc. We suggest that the transmission of compressible turbulence from an inner asterosheath into the local circumstellar interstellar medium surrounding a star, and the subsequent mode conversion to incompressible turbulence, may be a general mechanism by which stars drive turbulence in the interstellar medium.

Keywords: Interstellar magnetic fields, Heliopause, Interplanetary turbulence
Turbulent Heating in Solar Wind Thermodynamics. This paper considers the concept of wave-particle thermodynamic equilibrium in order to improve our understanding of the role of turbulent heating in the solar wind proton plasma. The thermodynamic equilibrium in plasmas requires the energy of a plasmon—the quantum of plasma fundamental oscillation—to be balanced by the proton-magnetized plasma energy, that is, the magnetic field and proton kinetic/thermal energy. This equilibrium has already been confirmed in several prior analyses, but also in this paper, by analyzing (i) multi-spacecraft data sets along the radial profile of the inner heliosphere, and (ii) representative data sets of a variety of 27 different space and astrophysical plasmas. Recently, it was shown that the slow mode of the near-Earth solar wind plasma is characterized by a missing energy source that is necessary for keeping the energy balance in the plasmon-proton-magnetized plasma. Here we show strong evidence that this missing energy is the turbulent energy heating the solar wind. In particular, we derive and compare the radial and velocity profiles of this missing energy and the turbulent energy in the inner heliosphere, also considering other minor contributions, such as the temperature of pickup protons. The connection of the missing plasmon-proton energy with the turbulent energy provides a new method for estimating and cross-examining the turbulent energy in space and astrophysical plasmas, while it confirms the universality of the involved new Planck-type constant that implies a large-scale quantization.

Keywords: Space plasmas, Heliosphere, Solar wind, Plasma astrophysics, Astronomy data analysis
Observational Analysis on the Early Evolution of a CME Flux Rope: Preflare Reconnection and Flux Rope’s Footpoint Drift. We study the early evolution of a hot-channel-like magnetic flux rope (MFR) toward eruption. Combining with imaging observation and magnetic field extrapolation, we find that the hot channel possibly originated from a preexisting seed MFR with a hyperbolic flux tube (HFT). In the precursor phase, three-dimensional tether-cutting reconnection at the HFT is most likely resulting in the heating and buildup of the hot channel. In this process, the forming hot channel was rapidly enlarged at its spatial size and slipped its feet to two remote positions. Afterward, it instantly erupted outwards with an exponential acceleration, leaving two core dimmings near its feet. We suggest that preflare reconnection at the HFT played a crucial role in enlarging the seed MFR and facilitating the onset of its final solar eruption. Moreover, a recently predicted drifting of MFR’s footpoints was detected at both core dimmings. In particular, we find that MFR’s west footpoint drift was induced by a new reconnection geometry among the erupting MFR’s leg and thereby inclined arcades. As MFR’s west footpoints gradually drifted to a new position, a set of newborn atypical flare loops connected into the west core dimming, causing a rapid decrease of dimmed area inside this core dimming and also generating a secondary flare ribbon at their remote feet. This reveals that core dimmings may suffer a pronounced diminishment due to the eruptive MFR’s footpoint drift, implying that mapping the real footpoints of the erupting MFR down to the Sun’s surface is more difficult than previously thought.

Keywords: Solar activity, Solar flares, Solar coronal mass ejections, Solar magnetic reconnection
Narrow-absorption Line Complex. IV. Line-driven Radiative Outflows in Broad-absorption Line Quasars. It has been reported that some broad-absorption lines (BALs) in quasar spectra can be decomposed into multiple narrow-absorption lines (NALs), which we define as “Type N BALs.” In this paper, using the spectra of 2005 BAL quasars from the Sloan Digital Sky Survey (SDSS), we have visually identified a total of 6764 C IV λλ1548 and 1551 NAL systems with 1.4186 ≤ z abs ≤ 3.8005, including 4174 C IV NAL systems within BAL troughs from 1349 quasars and 2590 outside BAL troughs from 1319 quasars. About two-thirds of the BAL quasars in the total sample contain Type N BALs, indicating the ubiquity of Type N BALs, which serve as a new perspective for studying outflows in the context of the NAL complex. Moreover, we find that, for both samples of C IV NAL systems within and outside BAL troughs, the distributions of velocity separation among distinct C IV NAL systems in the same quasar show significant excesses at the positions of C IV and Si IV doublet splittings, which offers statistical evidence for the idea that radiative forces play a significant role in driving both BAL and NAL outflows in BAL quasars.

Keywords: Quasars, Quasar absorption line spectroscopy, Broad-absorption line quasar
High-redshift Galaxy Formation with Self-consistently Modeled Stars and Massive Black Holes: Stellar Feedback and Quasar Growth. As computational resolution of modern cosmological simulations come closer to resolving individual star-forming clumps in a galaxy, the need for “resolution-appropriate” physics for a galaxy-scale simulation has never been greater. To this end, we introduce a self-consistent numerical framework that includes explicit treatments of feedback from star-forming molecular clouds (SFMCs) and massive black holes (MBHs). In addition to the thermal supernovae feedback from SFMC particles, photoionizing radiation from both SFMCs and MBHs is tracked through full three-dimensional ray tracing. A mechanical feedback channel from MBHs is also considered. Using our framework, we perform a state-of-the-art cosmological simulation of a quasar-host galaxy at z ∼ 7.5 for ∼25 Myr with all relevant galactic components, such as dark matter, gas, SFMCs, and an embedded MBH seed of ≳106 M ⊙. We find that feedback from SFMCs and an accreting MBH suppresses runaway star formation locally in the galactic core region. Newly included radiation feedback from SFMCs, combined with feedback from the MBH, helps the MBH grow faster by retaining gas that eventually accretes on to the MBH. Our experiment demonstrates that previously undiscussed types of interplay between gas, SFMCs, and a MBH may hold important clues about the growth and feedback of quasars and their host galaxies in the high-redshift universe.

Keywords: Supermassive black holes, Galaxy formation, Quasars, Galaxy dynamics, Galaxy nuclei, Galaxy kinematics, Galaxy evolution, Star formation, Active galactic nuclei, Galaxy circumnuclear disk, Interstellar medium
The Generalized Ion-sound Speed in Space and Astrophysical Plasmas. A generalized ion-sound speed for space and astrophysical plasmas in the regions of near- and far-from-thermal equilibrium is derived in the context of the new formulated invariant Kappa distribution. Inspired by the recent studies on the origin of polytropic behavior in space plasmas, it has been shown that the sound speed is connected to the extended polytropic index of Kappa distributed particles, which itself depends on the invariant Kappa index and the potential degrees of freedom. Generally, the ion-sound speed is a function of the polytropic index of Kappa distributed particles, which varies between two asymptotic regions of equilibrium and anti-equilibrium states. It is found that the ion-sound speed takes its maximum value in an equilibrium plasma and it reduces by approaching to the anti-equilibrium states. Furthermore, dispersion relation of the ion-acoustic waves in our formulism confirms, correspondingly, the recent study on the generalized formulation of Debye shielding in space plasmas. Finally, the classical and generalized relations between the ion-sound speed, the Debye length and the ion oscillation frequency have been discussed.

Keywords: Space plasmas, Theoretical techniques, Plasma physics
Nonthermal Motions in a Polar Coronal Hole Measured with Hinode/EIS during an on-Orbit Partial Solar Eclipse on 2017 August 21. We have performed a spectroscopic observation over the south polar coronal hole (PCH) with the Hinode Extreme-ultraviolet (EUV) Imaging Spectrometer (EIS) during an on-orbit partial solar eclipse. In this partial eclipse, the Moon passed through the EIS observing area that was set in the south PCH at the height of 0.9-1.4 solar radii. Using the lunar occultation, we have corrected for the scattered light contamination from bright regions of the Sun that is present in the dark PCH emission line profiles. The nonthermal width of the corrected emission line profile in the PCH increases from the limb toward the high-altitude corona. It has also been confirmed that the nonthermal width tends to decrease beyond ∼1.2 solar radii. These results are consistent with the model in which outward-propagating Alfvén waves start being dissipated at ∼1.2 solar radii, as previously reported. The reduced energy within ∼1.4 solar radii contributes to atmospheric heating and the initial acceleration for the solar wind in the low corona. The remaining energy flux at 1.4 solar radii may be dissipated in the distant corona and is sufficient to provide the additional acceleration required to drive the fast solar wind.

Keywords: Solar coronal heating, Solar wind, Solar coronal lines, Solar coronal waves, Solar coronal holes
Anisotropic Mass Segregation in Rotating Globular Clusters. We investigate the internal dynamics of anisotropic, rotating globular clusters with a multimass stellar population by performing new direct N-body simulations. In addition to the well-known radial mass segregation effect, where heavy stars and stellar remnants sink toward the center of the cluster, we find a mass segregation in the distribution of orbital inclinations as well. This newly discovered anisotropic mass segregation leads to the formation of a disk-like structure of massive objects near the equatorial plane of a rotating cluster. This result has important implications on the expected spatial distribution of black holes in globular clusters.

Keywords: Globular star clusters, Stellar kinematics, Stellar dynamics, Stellar mass black holes, Astrophysical processes, Dynamical friction, N-body simulations, Astrophysical black holes
The Structure of Solar Coronal Mass Ejections in the Extreme-ultraviolet Passbands. So far, most studies on the structure of coronal mass ejections (CMEs) are conducted through white-light coronagraphs, demonstrating that about one third of CMEs exhibit the typical three-part structure in the high corona (e.g., beyond 2 {R}⊙ ), i.e., the bright front, the dark cavity, and the bright core. In this paper, we address the CME structure in the low corona (e.g., below 1.3 {R}⊙ ) through extreme-ultraviolet (EUV) passbands and find that the three-part CMEs in the white-light images can possess a similar three-part appearance in the EUV images, i.e., a leading edge, a low-density zone, and a filament or hot channel. The analyses identify that the leading edge and the filament or hot channel in the EUV passbands evolve into the front and the core later within several solar radii in the white-light passbands, respectively. What is more, we find that the CMEs without an obvious cavity in the white-light images can also exhibit the clear three-part appearance in the EUV images, which means that the low-density zone in the EUV images (observed as the cavity in white-light images) can be compressed and/or transformed gradually by the expansion of the bright core and/or the reconnection of the magnetic field surrounding the core during the CME propagation outward. Our study suggests that more CMEs can possess the clear three-part structure in their early eruption stage. The nature of the low-density zone between the leading edge and the filament or hot channel is discussed.

Keywords: Solar magnetic reconnection, Solar extreme ultraviolet emission, Solar coronal mass ejection shocks, Solar coronal mass ejections, Solar filament eruptions
Cosmological Constraints from the Redshift Dependence of the Alcock-Paczynski Effect: Fourier Space Analysis. The tomographic Alcock-Paczynski (AP) method utilizes the redshift evolution of the AP distortion to place constraints on cosmological parameters. In previous works, it was performed via the anisotropic two-point correlation function statistic. In this work we consider the feasibility of conducting the analysis in the Fourier domain. We use the integrated galaxy power spectrum as a function of direction, {\hat{P}}{{Δ }k}(μ ), to quantify the magnitude of anisotropy in the large-scale structure clustering, and use its redshift variation to do the AP test. The method is tested on the large, high-resolution Big-MultiDark Planck simulation at redshifts z = 0-1. Testing the redshift evolution of {\hat{P}}{{Δ }k}(μ ) in the true cosmology and cosmologies deviating from the truth with δΩ m  = 0.1, δw = 0.3, we find that the redshift evolution of the AP distortion overwhelms the redshift space distortions effects by a factor of ∼1.7-3.6. The method works well throughout the range of k ∈ (0.2, 1.8) h Mpc-1. We tune the halo mass within the range 2 × 1013-1014 M ⊙, and find that the change of halo bias results in ≲5% change in {\hat{P}}{{Δ }k}(μ ), which is less significant compared with the cosmological effect. Our work shows that it is feasible to conduct the tomographic AP analysis in the Fourier space.

Keywords: Cosmological parameters from large-scale structure, Cosmological parameters, Large-scale structure of the universe
Gravitational Lens System PS J0147+4630 (Andromeda’s Parachute): Main Lensing Galaxy and Optical Variability of the Quasar Images. Because follow-up observations of quadruple gravitational lens systems are of extraordinary importance for astrophysics and cosmology, we present single-epoch optical spectra and r-band light curves of PS J0147+4630. This recently discovered system mainly consists of four images ABCD of a background quasar around a foreground galaxy G that acts as a gravitational lens. First, we use long-slit spectroscopic data in the Gemini Observatory Archive and a multi-component fitting to accurately resolve the spectra of A, D, and G. The spectral profile of G resembles that of an early-type galaxy at a redshift of 0.678 ± 0.001, which is about 20% higher than the previous estimate. Additionally, the stellar velocity dispersion is measured to ∼5% precision. Second, our early r-band monitoring with the Liverpool Telescope leads to accurate light curves of the four quasar images. Adopting time delays predicted by the lens model, the new lens redshift, and a standard cosmology, we report the detection of microlensing variations in C and D as large as ∼0.1 mag on timescales of a few hundred days. We also estimate an actual delay between A and B of a few days (B is leading), which demonstrates the big potential of optical monitoring campaigns of PS J0147+4630.

Keywords: Quasar microlensing, Strong gravitational lensing, Broad-absorption line quasar
On the Origin of SN 2016hil—A Type II Supernova in the Remote Outskirts of an Elliptical Host. Type II supernovae (SNe) stem from the core collapse of massive (&gt;8 M ⊙) stars. Due to their short lifespan, we expect a very low rate of such events in elliptical hosts, where the star formation rate is low, and which are mostly comprised of an old stellar population. SN 2016hil (iPTF16hil) is an SN II located in the extreme outskirts of an elliptical galaxy at z = 0.0608 (projected distance 27.2 kpc). It was detected near peak (M  r  ∼ -17 mag) 9 days after the last non-detection. The event has some potentially peculiar properties: it presented an apparently double-peaked light curve, and its spectra suggest low metallicity content (Z &lt; 0.4 Z ⊙). We place a tentative upper limit on the mass of a potential faint host at {log}\tfrac{M}{{M}⊙ }={7.27}-0.24+0.43 using deep optical imaging from Keck/LRIS. In light of this, we discuss the possibility of the progenitor forming locally and other more exotic formation scenarios such as a merger or common-envelope evolution causing a time-delayed explosion. Further observations of the explosion site in the UV are needed in order to distinguish between the cases. Regardless of the origin of the transient, observing a population of such seemingly hostless SNe II could have many uses, including an estimate the amount of faint galaxies in a given volume, and tests of the prediction of a time-delayed population of core-collapse SNe in locations otherwise unfavorable for the detection of such events.

Keywords: Binary stars, Core-collapse supernovae, Dwarf galaxies, Elliptical galaxies, Early-type galaxies
Ensemble Average of Three-dimensional Minkowski Tensors of a Gaussian Random Field in Redshift Space. We present the ensemble expectation values for the translation-invariant, rank-2 Minkowski tensors in three dimensions, for a linearly redshift-space-distorted Gaussian random field. The Minkowski tensors {W}10,2, {W}20,2 are sensitive to global anisotropic signals present within a field, and by extracting these statistics from the low-redshift matter density one can place constraints on the redshift-space distortion parameter β = f/b. We begin by reviewing the calculation of the ensemble expectation values &lt; {W}10,2&gt; , &lt; {W}20,2&gt; for isotropic, Gaussian random fields, then consider how these results are modified by the presence of a linearly anisotropic signal. Under the assumption that all fields remain Gaussian, we calculate the anisotropic correction due to redshift-space distortion in a coordinate system aligned with the line of sight, finding inequality between the diagonal elements of &lt; {W}10,2&gt; , &lt; {W}20,2&gt; . The ratio of diagonal elements of these matrices provides a set of statistics that are sensitive only to the redshift-space distortion parameter β. We estimate the Fisher information that can be extracted from the Minkowski tensors, and find {W}10,2 is more sensitive to β than {W}20,2, and a measurement of {W}10,2 accurate to ∼1% can yield a ∼ 4 % constraint on β. Finally, we discuss the difference between using the matrix elements of the Minkowski tensors directly against measuring the eigenvalues. For the purposes of cosmological parameter estimation we advocate the use of the matrix elements, to avoid spurious anisotropic signals that can be generated by the eigenvalue decomposition.

Keywords: Large-scale structure of the universe, Cosmology, Cosmological parameters from large-scale structure
Morphological Classification of G-band Bright Points Based on Deep Learning. The G-band bright points (GBPs) are driven by the granular convection flow, and appear with different morphologies in the quiet Sun, such as points, elongated chains, and knees. A point-like GBP represents a single slender flux tube, while the others represent the interaction of several slender flux tubes. This paper presents a deep-learning method, GBPs Mask Region-based Convolutional Neural Networks (GBP-MRCNN) for morphological classification of GBPs. A training set including 10,404 samples and a validation set including 2057 samples have been built. A total of 906 images as a testing set have been detected, segmented, and classified. They consist of 74,973 points (88.3%), 8660 elongated chains (10.2%), and 1239 knees (1.5%). GBP-MRCNN has achieved an efficient classification of GBPs with a mean average precision of 0.93. For points, elongated chains, and knees, the quiet Sun fractional area average values are 0.47%, 0.14%, and 0.03%, respectively. Correspondingly, the mean areas are (2.02 ± 0.69) × 104, (6.17 ± 1.71) × 104 and (6.99 ± 1.74) × 104 km2, respectively. The maximum intensity contrasts are 1.05 ± 0.12, 1.18 ± 0.17, and 1.36 ± 0.17, respectively. The mean eccentricities of points and elongated chains are 0.48 ± 0.23 and 0.89 ± 0.01, respectively. We adopt constituent points to describe how many points constitute a nonpoint-like GBP. The mean constituent points of elongated chains and knees are estimated as 2.77 ± 0.57 and 3.06 ± 0.65, respectively. The maximum length of the elongated chains can extend to over 1000 km, which corresponds to over eight single slender flux tubes. The characteristics of GBPs with different morphologies can be explained by the interaction between magnetic flux tubes and photospheric convection, and then help to build improved magnetic flux tube models.

Keywords: Astronomical methods, Quiet sun, Convolutional neural networks, Solar photosphere
Formation and Eruption of a Mini-sigmoid Originating in Coronal Hole. In this paper, we study in detail the evolution of a mini-sigmiod originating in a cross-equatorial coronal hole, where the magnetic field is mostly open and seriously distinct from the closed background field above active-region sigmoids. The source region first appeared as a bipole, which subsequently experienced a rapid emergence followed by a long-term decay. Correspondingly, the coronal structure initially appeared as arc-like loops, then gradually sheared and transformed into continuously sigmoidal loops, mainly owing to flux cancellation near the polarity inversion line. The temperature of J-shaped and sigmoidal loops is estimated to be about 2.0 × 106 K, greater than that of the background coronal hole. Using the flux-rope insertion method, we further reconstruct the nonlinear force-free fields that well reproduces the transformation of the potential field into a sigmoidal field. The fact that the sheared and sigmoidal loops are mainly concentrated at around the high-Q region implies that the reconnection most likely takes place there to form the sigmoidal field and heat the plasma. Moreover, the twist of sigmoidal field lines is estimated to be around 0.8, less than the values derived for the sigmoids from active regions. However, the sigmoidal flux may quickly enter an unstable regime at the very low corona (&lt;10 Mm) due to the open background field. The results suggest that the mini-sigmoid, at least the one in our study, has the same formation and eruption process as the large-scale one, but is significantly influenced by the overlying flux.

Keywords: Solar activity, Solar magnetic fields, Solar ultraviolet emission, Solar corona