Sazuna/UAT_keywords huggingface dataset:
Dynamical Hotness, Star Formation Quenching, and Growth of Supermassive Black Holes. A stellar system is dynamically hot when its kinetic energy is dominated by random motion represented by the velocity dispersion σ hot. We use MaNGA data to obtain the inner and outer dispersion of a galaxy, σ in and σ out, to characterize its dynamical status and study its connection with star formation quenching and the growth of its supermassive black hole (SMBH). We divide galaxies into fully quenched (FQGs), partially quenched (PQGs), and fully star-forming (FSGs) populations, and identify quenched central cores (QCCs) in PQGs. The galaxy distribution in (σ in/σ hot)-(σ out/σ hot) diagram is L-shaped, consisting of a horizontal sequence (σ out/σ hot ~ 0) and a vertical sequence (σ in/σ hot ~ 1). FQGs and QCCs are located at the top of the vertical sequence, σ out/σ hot ~ 1, and are thus dynamically hot over their entire bodies. PQGs reside along the vertical sequence, so they have hot centers but cold outskirts. FSGs are diverse and can be found in both sequences. Galaxy structural properties, star formation, and AGN activities make a transition along the horizontal sequence at σ in/σ hot ~ 0.5, and along the vertical sequence at σ out/σ hot ~ 0.5. The fractions of optical AGNs and barred galaxies increase rapidly in the first transition and decline rapidly in the second; radio galaxies are located at the top of the vertical sequence. Our results demonstrate that star formation quenching and SMBH growth are effective only in dynamically hot systems. A simple model along this line can reproduce the observed SMBH scaling relations. We discuss how secular processes and strong interactions can make a system dynamically hot, and lead to the SMBH growth and star formation quenching.

Keywords: Supermassive black holes, Galaxy formation, Galaxy dynamics, Galaxy classification systems, Scaling relations, Active galactic nuclei, Galaxy evolution, Star formation, Galaxy quenching
Interplay between Anisotropy- and Skewness-driven Whistler Instabilities in the Solar Wind under the Core-Strahlo Model. Temperature anisotropy and field-aligned skewness are commonly observed nonthermal features in electron velocity distributions in the solar wind. These characteristics can act as a source of free energy to destabilize different electromagnetic wave modes, which may alter the plasma state through wave-particle interactions. Previous theoretical studies have mainly focused on analyzing these nonthermal features and self-generated instabilities individually. However, to obtain a more accurate and realistic understanding of the kinetic processes in the solar wind, it is necessary to examine the interplay between these two energy sources. By means of linear kinetic theory, in this paper we investigate the excitation of the parallel propagating whistler mode, when it is destabilized by electron populations exhibiting both temperature anisotropy and field-aligned strahl or skewness. To describe the solar wind electrons, we adopt the core-strahlo model as an alternative approach. This model offers the advantage of representing the suprathermal features of halo and strahl electrons, using a single skew-kappa distribution already known as the strahlo population. Our findings show that when the electron strahlo exhibits an intrinsic temperature anisotropy, this suprathermal population becomes a stronger and more efficient source of free energy for destabilizing the whistler mode. This suggests the greater involvement of the anisotropic strahlo in processes conditioned by wave-particle interactions. The present results also suggest that the contribution of core anisotropy can be safely disregarded when assessing the importance of instabilities driven by the suprathermal population. This allows for a focused study, particularly regarding the regulation of the electron heat flux in the solar wind.

Keywords: Space plasmas, Solar wind, Plasma astrophysics
Photospheric and Chromospheric Magnetic Field Evolution during the X1.6 Flare in Active Region NOAA 12192. We report on observations acquired by the Interferometric Bidimensional Spectropolarimeter (IBIS) during SOL2014-10-22T14:02, an X1.6 flare that occurred in active region NOAA 12192, taken in the Fe I 617.30 nm and Ca II 854.2 nm line profiles. We analyze polarization signatures in the Stokes profiles of the two lines across one of the flare ribbons. Focusing our attention on the chromospheric signals and using the weak-field approximation (WFA), we study the temporal variation of the line-of-sight (LOS) magnetic field. We find variations of the magnetic field or the opacity along the flare ribbon, in most cases within the first 3 minutes of the observation just after the flare peak, during the tail of the flare impulsive phase. This result was validated by the STiC inversion of the pixels used for the WFA analysis. The analysis of the photospheric magnetic field shows that in this layer, the LOS magnetic field does not show the same changes observed in the chromosphere in the selected pixels, nor clear evidence of changes along the polarity inversion line around a magnetic polarity intrusion. In this respect, we also find that the temporal observing window is not suitable for assessing the presence of stepwise changes. The nonlinear force-free field extrapolations, together with the analysis of the ribbons' isophotes obtained from Interface Region Imaging Spectrograph data, suggest that the region corresponding to the magnetic intrusion observed by IBIS is characterized by a complex magnetic connectivity and is almost cospatial with the area affected by the initial energy release.

Keywords: Spectropolarimetry, Solar flares, Solar magnetic fields, Active solar chromosphere, High angular resolution
On the Properties of Inverse Compton Spectra Generated by Upscattering a Power-law Distribution of Target Photons. Relativistic electrons are an essential component in many astrophysical sources, and their radiation may dominate the high-energy bands. Inverse Compton (IC) emission is the radiation mechanism that plays the most important role in these bands. The basic properties of IC, such as the total and differential cross sections, have long been studied; the properties of the IC emission depend strongly not only on the emitting electron distribution but also on the properties of the target photons. This complicates the phenomenological studies of sources, where target photons are supplied from a broad radiation component. We study the spectral properties of IC emission generated by a power-law distribution of electrons on a power-law distribution of target photons. We approximate the resulting spectrum by a broken-power-law distribution and show that there can be up to three physically motivated spectral breaks. If the target photon spectrum extends to sufficiently low energies, ${\varepsilon }_{\min }\lt {m}_{e}^{2}{c}^{4}/{E}_{\max }$ (m  e  and c are electron mass and speed of light, respectively; ${\varepsilon }_{\min }$ and ${E}_{\max }$ are the minimum/maximum energies of target photons and electrons, respectively), then the high-energy part of the IC component has a spectral slope typical for the Thomson regime with an abrupt cutoff close to ${E}_{\max }$ . The spectra typical for the Klein-Nishina regime are formed above ${m}_{e}^{2}{c}^{4}/{\varepsilon }_{\min }$ . If the spectrum of target photons features a cooling break, i.e., a change of the photon index by 0.5 at ɛ br, then the transition to the Klein-Nishina regime proceeds through an intermediate change of the photon index by 0.5 at ${m}_{e}^{2}{c}^{4}/{\varepsilon }_{\mathrm{br}}$ .

Keywords: Gamma-ray sources, Gamma-ray bursts, Gamma-ray transient sources, Gamma-rays
Inferring the Solar Meridional Circulation Flow Profile by Applying Bayesian Methods to Time-Distance Helioseismology. Mapping the large-scale subsurface plasma flow profile within the Sun has been attempted using various methods for several decades. One such flow in particular is the meridional circulation, for which numerous studies have been published. However, such studies often show disagreement in structure. In an effort to constrain the flow profile from the data, a Bayesian Markov chain Monte Carlo framework has been developed to take advantage of the advances in computing power that allow for the efficient exploration of high-dimensional parameter spaces. This study utilizes helioseismic travel-time difference data covering a span of 21 years and a parameterized model of the meridional circulation to find the most likely flow profiles. Tests were carried out on artificial data to determine the ability of this method to recover expected solar-like flow profiles, as well as a few extreme cases. We find that this method is capable of recovering the input flows of both single- and double-cell flow structures. Some inversion results indicate potential differences in meridional circulation between the two solar cycles in terms of both magnitude and morphology, in particular in the mid-convection zone. Of these, the most likely solutions show that solar cycle 23 has a large single-celled profile, while cycle 24 shows weaker flows in general and hints toward a double-celled structure.

Keywords: Solar cycle, Solar interior, Helioseismology, The Sun, Solar physics, Solar meridional circulation
High-energy Neutrino Constraints on Cosmic-Ray Reacceleration in Radio Halos of Massive Galaxy Clusters. A fraction of merging galaxy clusters host diffuse radio emission in their central region, termed a giant radio halo (GRH). The most promising mechanism of GRHs is the reacceleration of nonthermal electrons and positrons by merger-induced turbulence. However, the origin of these seed leptons has been under debate, and either protons or electrons can be primarily accelerated particles. In this work, we demonstrate that neutrinos can be used as a probe of physical processes in galaxy clusters and discuss possible constraints on the number of relativistic protons in the intracluster medium with the existing upper limits by IceCube. We calculate radio and neutrino emission from massive (&gt;1014 M ⊙) galaxy clusters using the cluster population model of Nishiwaki &amp; Asano. This model is compatible with the observed statistics of GRHs, and we find that the contribution of GRHs to the isotropic radio background observed with the ARCADE-2 experiment should be subdominant. Our fiducial model predicts the all-sky neutrino flux that is consistent with IceCube's upper limit from the stacking analysis. We also show that the neutrino upper limit gives meaningful constraints on the parameter space of the reacceleration model, such as the electron-to-proton ratio of the primary cosmic rays and the magnetic field; in particular, the secondary scenario, where the seed electrons mostly originate from inelastic pp collisions, can be constrained even in the presence of reacceleration.

Keywords: Galaxy clusters
Survey of CH<SUB>3</SUB>NH<SUB>2</SUB> and its Formation Process. We present the observational results of a precursor of glycine, methylamine (CH3NH2), together with methanol (CH3OH) and methanimine (CH2NH) for the high-mass star-forming regions NGC 6334I, G10.47+0.03, G31.41+0.3, and W51 e1/e2 using the Atacama Large Millimeter/submillimeter Array. The molecular abundances of these sources were derived using the CASSIS spectrum analyzer and compared with our state-of-the-art three-phase chemical model NAUTILUS. We found that the observed abundance ratio of CH3NH2/CH3OH is between 0.008 and 1.0 for all sources, except for NGC 6334I MM3, where a ratio less than 0.002 is found. This may be due to its later evolutionary stage relative to the other cores. We also found that the observed CH3NH2/CH3OH ratio agrees well with the three-phase chemical model NAUTILUS, which includes the formation of CH3NH2 on the grain surface via a series of hydrogenation processes of HCN. This result clearly shows the importance of hydrogenation processes to form CH3NH2.

Keywords: Interstellar molecules, Interstellar abundances, Astrobiology, Star formation, Interstellar medium
Gravitational Instability, Spiral Substructure, and Modest Grain Growth in a Typical Protostellar Disk: Modeling Multiwavelength Dust Continuum Observations of TMC1A. Embedded class 0/I protostellar disks represent the initial condition for planet formation. This calls for a better understanding of their bulk properties and the dust grains within them. We model multiwavelength dust continuum observations of the disk surrounding the class I protostar TMC1A to provide insight on these properties. The observations can be well fit by a gravitationally self-regulated (i.e., marginally gravitationally unstable and internally heated) disk model with surface density Σ ~ 1720(R/10 au)-1.96 g cm-2 and midplane temperature T mid ~ 185(R/10 au)-1.27 K. The observed disk contains an m = 1 spiral substructure; we use our model to predict the spiral's pitch angle, and the prediction is consistent with the observations. This agreement serves as both a test of our model and strong evidence of the gravitational nature of the spiral. Our model estimates a maximum grain size ${a}_{\max }\sim 196{(R/10\,\mathrm{au})}^{-2.45}\mu {\rm{m}}$ , which is consistent with grain growth being capped by a fragmentation barrier with a threshold velocity of ~1 m s-1. We further demonstrate that the observational properties of TMC1A are typical among the observed population of class 0/I disks, which hints that traditional methods of disk data analysis based on Gaussian fitting and the assumption of optically thin dust emission could have systematically underestimated the disk size and mass and overestimated the grain size.

Keywords: Gravitational instability, Astronomy data modeling, Dust continuum emission, Protoplanetary disks, Planet formation
Hybrid Simulation and Quasi-linear Theory of Bi-Kappa Proton Instabilities. The quasi-steady states of collisionless plasmas in space (e.g., in the solar wind and planetary environments) are governed by the interactions of charged particles with wave fluctuations. These interactions are responsible not only for the dissipation of plasma waves but also for their excitation. The present analysis focuses on two instabilities, mirror and electromagnetic ion cyclotron instabilities, associated with the same proton temperature anisotropy T ⊥ &gt; T ∥ (where ⊥, ∥ are directions defined with respect to the local magnetic field vector). Theories relying on standard Maxwellian models fail to link these two instabilities (i.e., predicted thresholds) to the proton quasi-stable anisotropies measured in situ in a completely satisfactory manner. Here we revisit these instabilities by modeling protons with the generalized bi-Kappa (bi-κ power-law) distribution, and by a comparative analysis of a 2D hybrid simulation with the velocity-moment-based quasi-linear (QL) theory. It is shown that the two methods feature qualitative and, even to some extent, quantitative agreement. The reduced QL analysis based upon the assumption of a time-dependent bi-Kappa model thus becomes a valuable theoretical approach that can be incorporated into the present studies of solar wind dynamics.

Keywords: The Sun, Solar wind, Fast solar wind
Three-dimensional General-relativistic Simulations of Neutrino-driven Winds from Magnetized Proto-Neutron Stars. Formed in the aftermath of a core-collapse supernova or neutron star merger, a hot proto-neutron star (PNS) launches an outflow driven by neutrino heating lasting for up to tens of seconds. Though such winds are considered potential sites for the nucleosynthesis of heavy elements via the rapid neutron capture process (r-process), previous work has shown that unmagnetized PNS winds fail to achieve the necessary combination of high entropy and/or short dynamical timescale in the seed nucleus formation region. We present three-dimensional general-relativistic magnetohydrodynamical simulations of PNS winds which include the effects of a dynamically strong (B ≳ 1015 G) dipole magnetic field. After initializing the magnetic field, the wind quickly develops a helmet-streamer configuration, characterized by outflows along open polar magnetic field lines and a "closed" zone of trapped plasma at lower latitudes. Neutrino heating within the closed zone causes the thermal pressure of the trapped material to rise in time compared to the polar outflow regions, ultimately leading to the expulsion of this matter from the closed zone on a timescale of ~60 ms, consistent with the predictions of Thompson. The high entropies of these transient ejecta are still growing at the end of our simulations and are sufficient to enable a successful second-peak r-process in at least a modest ≳1% of the equatorial wind ejecta.

Keywords: Neutron stars, High energy astrophysics, R-process, Supernova remnants, Stellar winds, General relativity, Magnetars
Toward an Optimal Reconstruction of the Shear Field with PDF-folding. Weak lensing provides a direct way of mapping the density distribution in the Universe. To reconstruct the density field from the shear catalog, an important step is to build the shear field from the shear catalog, which can be quite nontrivial due to the inhomogeneity of the background galaxy distribution and the shape noise. We propose the PDF-folding method as a statistically optimal way of reconstructing the shear field. It is an extention of the PDF-SYM method, which was previously designed for optimizing the stacked shear signal as well as the shear-shear correlation for the Fourier_Quad shear estimators. PDF-folding does not require smoothing kernels as in traditional methods, therefore it suffers less information loss on small scales and avoids possible biases due to the spatial variation in the shear on the scale of the kernel. We show with analytic reasoning as well as numerical examples that the new method can reach the optimal signal-to-noise ratio on the reconstructed shear map under general observing conditions, i.e., with inhomogeneous background densities or masks. We also show the performance of the new method on real data around foreground galaxy clusters.

Keywords: Weak gravitational lensing, Gravitational lensing shear
Flare Duty Cycle of Gamma-Ray Blazars and Implications for High-energy Neutrino Emission. Gamma-ray flares of blazars may be accompanied by high-energy neutrinos due to interactions of high-energy cosmic rays in the jet with photons, as suggested by the detection of the high-energy neutrino IceCube-170922A during a major gamma-ray flare from blazar TXS 0506+056 at the ~3σ significance level. In this work, we present a statistical study of gamma-ray emission from blazars to constrain the contribution of gamma-ray flares to their neutrino output. We construct weekly binned light curves for 145 gamma-ray bright blazars in the Fermi Large Area Telescope Monitored Source List adding TXS 0506+056. We derive the fraction of time spent in the flaring state (flare duty cycle) and the fraction of energy released during each flare from the light curves with a Bayesian blocks algorithm. We find that blazars with lower flare duty cycles and energy fractions are more numerous among our sample. We identify a significant difference in flare duty cycles between blazar subclasses at a significance level of 5%. Then using a general scaling relation for the neutrino and gamma-ray luminosities, ${L}_{\nu }\propto {({L}_{\gamma })}^{\gamma }$ with a weighting exponent of γ = 1.0-2.0, normalized to the quiescent gamma-ray or X-ray flux of each blazar, we evaluate the neutrino energy flux of each gamma-ray flare. The gamma-ray flare distribution indicates that blazar neutrino emission may be dominated by flares for γ ≳ 1.5. The neutrino energy fluxes for 1 week and 10 yr bins are compared with the decl.-dependent IceCube sensitivity to constrain the standard neutrino emission models for gamma-ray flares. Finally, we present the upper-limit contribution of blazar gamma-ray flares to the isotropic diffuse neutrino flux.

Keywords: Blazars, Neutrino astronomy, Gamma-ray astronomy, High energy astrophysics
Constraining the Gravitational Potential from the Projected Morphology of Extragalactic Tidal Streams. The positions and velocities of stellar streams have been used to constrain the mass and shape of the Milky Way's dark matter halo. Several extragalactic streams have already been detected, though it has remained unclear what can be inferred about the gravitational potential from only 2D photometric data of a stream. We present a fast method to infer halo shapes from the curvature of 2D projected stream tracks. We show that the stream curvature vector must point within 90° of the projected acceleration vector, in the absence of recent time-dependent perturbations. While insensitive to the total magnitude of the acceleration, and therefore the total mass, applying this constraint along a stream can determine halo shape parameters and place limits on disk-to-halo mass ratios. The most informative streams are those with sharp turns or flat segments, since these streams sample a wide range of curvature vectors over a small area (sharp turns) or have a vanishing projected acceleration component (flat segments). We apply our method to low surface brightness imaging of NGC 5907, and find that its dark matter halo is oblate. Our analytic approach is significantly faster than other stream modeling techniques, and indicates which parts of a stream contribute to constraints on the potential. The method enables a measurement of dark matter halo shapes for thousands of systems using stellar stream detections expected from upcoming facilities like Rubin and Roman.

Keywords: Galaxy stellar halos, Tidal tails, Dark matter, Stellar streams
Giant Impact Events for Protoplanets: Energetics of Atmospheric Erosion by Head-on Collision. Numerous exoplanets with masses ranging from Earth to Neptune and radii larger than Earth have been found through observations. These planets possess atmospheres that range in mass fractions from 1% to 30%, reflecting the diversity of atmospheric mass fractions. Such diversities are supposed to be caused by differences in the formation processes or evolution. Here, we consider head-on giant impacts onto planets causing atmosphere losses in the later stage of their formation. We perform smoothed particle hydrodynamic simulations to study the impact-induced atmosphere loss of young super-Earths with 10%-30% initial atmospheric mass fractions. We find that the kinetic energy of the escaping atmosphere is almost proportional to the sum of the kinetic impact energy and self-gravitational energy released from the merged core. We derive the relationship between the kinetic impact energy and the escaping atmosphere mass. The giant impact events for planets of comparable masses are required in the final stage of the popular scenario of rocky planet formation. We show it results in a significant loss of the atmosphere, if the impact is a head-on collision with comparable masses. This latter fact provides a constraint on the formation scenario of rocky planets with substantial atmospheres.

Keywords: Impact phenomena, Hydrodynamical simulations, Super Earths, Exoplanet atmospheres