Sazuna/UAT_keywords huggingface dataset:
Magnetorotational Explosion of a Massive Star Supported by Neutrino Heating in General Relativistic Three-dimensional Simulations. We present results of three-dimensional (3D), radiation-magnetohydrodynamics (MHD) simulations of core-collapse supernovae in full general relativity (GR) with spectral neutrino transport. In order to study the effects of the progenitor's rotation and magnetic fields, we compute three models, where the precollapse rotation rate and magnetic fields are included parametrically to a 20 M⊙ star. While we find no shock revival in our two nonmagnetized models during our simulation times (∼500 ms after bounce), the magnetorotational (MR) driven shock expansion immediately initiates after bounce in our rapidly rotating and strongly magnetized model. We show that the expansion of the MR-driven flows toward the polar directions is predominantly driven by the magnetic pressure, whereas the shock expansion toward the equatorial direction is supported by neutrino heating. Our detailed analysis indicates that the growth of the so-called kink instability may hinder the collimation of jets, resulting in the formation of broader outflows. Furthermore, we find a dipole emission of lepton number, only in the MR explosion model, whose asymmetry is consistent with the explosion morphology. Although it is similar to the lepton number emission self-sustained asymmetry (LESA), our analysis shows that the dipole emission occurs not from the proto-neutron star convection zone but from above the neutrino sphere, indicating that it is not associated with the LESA. We also report several unique neutrino signatures, which are significantly dependent on both the time and the viewing angle, if observed, possibly providing rich information regarding the onset of the MR-driven explosion.

Keywords: Supernova neutrinos, Radiative magnetohydrodynamics, Core-collapse supernovae, Supernova dynamics, Magnetohydrodynamical simulations
Constraints on the Distances and Timescales of Solid Migration in the Early Solar System from Meteorite Magnetism. The migrations of solid objects throughout the solar system are thought to have played key roles in disk evolution and planet formation. However, our understanding of these migrations is limited by a lack of quantitative constraints on their timings and distances recovered from laboratory measurements of meteorites. The protoplanetary disk supported a magnetic field that decreased in intensity with heliocentric distance. As such, the formation distances of the parent asteroids of ancient meteorites can potentially be constrained by paleointensity measurements of these samples. Here, we find that the WIS 91600 ungrouped C2 chondrite experienced an ancient field intensity of 4.4 ± 2.8 μT. Combined with the thermal history of this meteorite, magnetohydrodynamical models suggest the disk field reached 4.4 μT at ∼9.8 au, indicating that the WIS 91600 parent body formed in the distal solar system. Because WIS 91600 likely came to Earth from the asteroid belt, our recovered formation distance argues that this body previously traveled from ∼10 au to 2-3 au, supporting the migration of asteroid-sized bodies throughout the solar system. WIS 91600 also contains chondrules, calcium-aluminum-rich inclusions and amoeboid olivine aggregates, indicating that some primitive millimeter-sized solids that formed in the innermost solar system migrated outward to ∼10 au within ∼3-4 Myr of solar system formation. Moreover, the oxygen isotopic compositions of proposed distal meteorites (WIS 91600, Tagish Lake and CI chondrites) argue that the CM, CO, and CR chondrites contain micrometer-scale dust and ice that originated in the distal solar system.

Keywords: Chondrites, Kuiper belt, Primordial magnetic fields, Chondrules, Protoplanetary disks, Meteorites, Asteroid belt, Magnetic fields
Kinematics of Filaments in Cooling Flow Clusters and Heating by Mixing. We compare a recent study of the kinematics of optical filaments in three cooling flow clusters of galaxies with previous numerical simulations of jet-inflated hot bubbles, and conclude that the velocity structure functions (VSFs) of the filaments better fit direct excitation by the jets than by turbulent cascade from the largest turbulent eddies. The observed VSFs of the optical filaments in the three clusters are steeper than that expected from a classical cascade in turbulent dissipation. Our three-dimensional hydrodynamical simulations show that as the jets inflate bubbles in the intracluster medium (ICM), they form vortexes in a large range of scales. These vortexes might drive the ICM turbulence with eddies of over more than an order of magnitude in size. A direct excitation of turbulence by the vortexes that the jets form and the slow turbulent dissipation imply that heating the ICM by mixing with hot bubbles is more efficient than heating by turbulent dissipation.

Keywords: Galaxy clusters, Cooling flows, Galaxy jets, Circumgalactic medium
Energetic Electron Acceleration by Ion-scale Magnetic Islands in Turbulent Magnetic Reconnection: Particle-in-cell Simulations and ARTEMIS Observations. Particle-in-cell simulations show that numerous ion-scale magnetic islands can be formed in a turbulent magnetic reconnection region. These islands can confine and accelerate electrons to high energies effectively, causing the energetic electron energy flux to peak at the center of each island. ARTEMIS spacecraft observations of turbulent reconnection outflows in Earth's magnetotail reveal that peaks in the energetic electron energy flux are well correlated with bipolar signatures of reconnected magnetic field, which are indicative of ion-scale magnetic islands, providing observational evidence for this acceleration process.

Keywords: Interplanetary particle acceleration, Solar magnetic reconnection, Heliosphere
Anomalous Bremsstrahlung and the Structure of Cosmic-Ray Electron-Positron Fluxes at the GeV-TeV Energy Range. We reveal that the energy spectra of electrons-positrons in primary cosmic rays measured at atmosphere tops have double structures: an excess component ${{\rm{\Phi }}}_{{e}^{+}}^{s}(E)={{\rm{\Phi }}}_{{e}^{-}}^{s}(E)$ around $400\,\mathrm{GeV}$, which originates from a strong e+ e--source. and the distorted background ${{\rm{\Phi }}}_{{e}^{-}}^{0}(E)$ . We supposed that the difference between AMS-CALET and Fermi-LAT-DAMPE data originates from the energy loss of the fluxes due to the anomalous bremsstrahlung effect at a special window. The evolution of spectra under the anomalous bremsstrahlung effect satisfies an improved electromagnetic cascade equation. The above spectra are parameterized and they can be used for further physics studies. We suggest checking previous applications of the Bethe-Heitler formula when studying the propagation of high-energy electrons and photons.

Keywords: Galactic cosmic rays, Spectral energy distribution, High energy astrophysics
Impact of Planetary Mass Uncertainties on Exoplanet Atmospheric Retrievals. In current models used to interpret exoplanet atmospheric observations, the planetary mass is treated as a prior and is measured/estimated independently with external methods, such as radial velocity or transit timing variation techniques. This approach is necessary as available spectroscopic data do not have sufficient wavelength coverage and/or signal-to-noise to infer the planetary mass. We examine here whether the planetary mass can be directly retrieved from transit spectra as observed by future space observatories, which will provide higher quality spectra. More in general, we quantify the impact of mass uncertainties on spectral retrieval analyses for a host of atmospheric scenarios. Our approach is both analytical and numerical: we first use simple approximations to extract analytically the influence of each atmospheric/planetary parameter to the wavelength-dependent transit depth. We then adopt a fully Bayesian retrieval model to quantify the propagation of the mass uncertainty onto other atmospheric parameters. We found that for clear-sky, gaseous atmospheres the posterior distributions are the same when the mass is known or retrieved. The retrieved mass is very accurate, with a precision of more than 10%, provided the wavelength coverage and signal-to-noise ratio are adequate. When opaque clouds are included in the simulations, the uncertainties in the retrieved mass increase, especially for high altitude clouds. However, atmospheric parameters such as the temperature and trace-gas abundances are unaffected by the knowledge of the mass. Secondary atmospheres, expected to be present in many super-Earths, are more challenging due to the higher degree of freedom for the atmospheric main component, which is unknown. For broad wavelength range and adequate signal-to-noise observations, the mass can still be retrieved accurately and precisely if clouds are not present, and so are all the other atmospheric/planetary parameters. When clouds are added, we find that the mass uncertainties may impact substantially the retrieval of the mean molecular weight: an independent characterization of the mass would therefore be helpful to capture/confirm the main atmospheric constituent.

Keywords: Exoplanet atmospheres
The Interplay between Star Formation and Black Hole Accretion in Nearby Active Galaxies. Black hole accretion is widely thought to influence star formation in galaxies, but the empirical evidence for a physical correlation between star formation rate (SFR) and the properties of active galactic nuclei (AGNs) remain highly controversial. We take advantage of a recently developed SFR estimator based on the [O II] λ3727 and [O III] λ5007 emission lines to investigate the SFRs of the host galaxies of more than 5800 type-1 and 7600 type-2 AGNs with z &lt; 0.35. After matching in luminosity and redshift, we find that type-1 and type-2 AGNs have a similar distribution of internal reddening, which is significant and corresponds to ∼109 M⊙ of cold molecular gas. In spite of their comparable gas content, type-2 AGNs, independent of stellar mass, Eddington ratio, redshift or molecular gas mass, exhibit intrinsically stronger star formation activity than type-1 AGNs, in apparent disagreement with the conventional AGN unified model. We observe a tight, linear relation between AGN luminosity (accretion rate) and SFR, one that becomes more significant toward smaller physical scales, suggesting that the link between the AGN and star formation occurs in the central kpc-scale region. This, along with a correlation between SFR and Eddington ratio in the regime of super-Eddington accretion, can be interpreted as evidence that star formation is impacted by positive feedback from the AGN.

Keywords: Active galaxies, Star formation, Interstellar medium
Signatures of Strangeness in Neutron Star Merger Remnants. Neutron star (NS) mergers provide us with information rich in physics using multimessenger astrophysical observations. One of the probable remnants of such a merger is a differentially rotating hot hypermassive NS. The stability of the merger remnant crucially depends on the underlying equation of state and thus provides a method to probe the nature of dense matter in NSs. In this work, we search for possible signatures of strangeness-containing matter in NS interiors on the secular stability of the merger remnant. We also use recently proposed methods to make a rough estimate of the collapse time of the merger remnant and the threshold mass above which the merger promptly collapses to a black hole.

Keywords: Neutron stars, Relativistic stars, Neutron star cores
ALMA Observations of NGC 6334S. I. Forming Massive Stars and Clusters in Subsonic and Transonic Filamentary Clouds. We present Atacama Large Millimeter/submillimeter Array (ALMA) and Karl G. Jansky Very Large Array (JVLA) observations of the massive infrared dark cloud NGC 6334S (also known as IRDC G350.56+0.44), located at the southwestern end of the NGC 6334 molecular cloud complex. The H13CO+ and NH2D lines covered by the ALMA observations at a ∼3″ angular resolution (∼0.02 pc) reveal that the spatially unresolved nonthermal motions are predominantly subsonic and transonic, a condition analogous to that found in low-mass star-forming molecular clouds. The observed supersonic nonthermal velocity dispersions in massive star-forming regions, often reported in the literature, might be significantly biased by poor spatial resolutions that broaden the observed line widths owing to unresolved motions within the telescope beam. Our 3 mm continuum image resolves 49 dense cores, whose masses range from 0.17 to 14 M☉. The majority of them are resolved with multiple velocity components. Our analyses of these gas velocity components find an anticorrelation between the gas mass and the virial parameter. This implies that the more massive structures tend to be more gravitationally unstable. Finally, we find that the external pressure in the NGC 6334S cloud is important in confining these dense structures and may play a role in the formation of dense cores and, subsequently, the embedded young stars.

Keywords: Radio spectroscopy, Early-type stars, Submillimeter astronomy, Massive stars, Protoclusters, Molecular spectroscopy, Star formation, Radio interferometers, Radio continuum emission, Protostars
A Second-order Moment of Microlensing Variability as a Novel Tool to Constrain Source Emission Size or Discrete Lens Demographics in Extragalactic Research. We define a second-order moment of the observational differential microlensing curves that can be used to impose constraints on physical properties of lensed quasars. We show that this quantity is sensitive both to variations in the source size and the deflector mass. We formulize a methodology to recover the source size from the observational measurements when the mass spectrum is fixed. As a case study, we test it with a sample of four quadruple lenses, both in simulated scenarios and with real data from the Chandra X-ray Observatory. In our simulations with a uniform stellar population the method works best to detect sources around 0.1 Einstein radii, giving correct upper/lower limits for much smaller/bigger sizes without requiring a big leap in additional computational effort as compared to a single-epoch approach, yet taking advantage of multi-epoch information. We apply the method to a small sample of X-ray data from four objects assuming a range of star masses, and obtain a degeneracy relation between the source size and deflector mass. Combined with previous estimates for the size of the X-ray corona, the degeneracy relation suggests that X-ray microlensing is mainly induced by planetary mass objects.

Keywords: Accretion, Black hole physics, Quasars, Gravitational lensing, Quasar microlensing
Signatures of Velocity-dependent Dark Matter Self-interactions in Milky Way-mass Halos. We explore the impact of elastic, anisotropic, velocity-dependent dark matter (DM) self-interactions on the host halo and subhalos of Milky Way (MW)-mass systems. We consider a generic self-interacting dark matter (SIDM) model parameterized by the masses of a light mediator and the DM particle. The ratio of these masses, w, sets the velocity scale above which momentum transfer due to DM self-interactions becomes inefficient. We perform high-resolution zoom-in simulations of an MW-mass halo for values of w that span scenarios in which self-interactions either between the host and its subhalos or only within subhalos efficiently transfer momentum, and we study the effects of self-interactions on the host halo and on the abundance, radial distribution, orbital dynamics, and density profiles of subhalos in each case. The abundance and properties of surviving subhalos are consistent with being determined primarily by subhalo-host halo interactions. In particular, subhalos on radial orbits in models with larger values of the cross section at the host halo velocity scale are more susceptible to tidal disruption owing to mass loss from ram pressure stripping caused by self-interactions with the host. This mechanism suppresses the abundance of surviving subhalos relative to collisionless DM simulations, with stronger suppression for larger values of w. Thus, probes of subhalo abundance around MW-mass hosts can be used to place upper limits on the self-interaction cross section at velocity scales of $\sim 200\ \mathrm{km}\,{{\rm{s}}}^{-1}$, and combining these measurements with the orbital properties and internal dynamics of subhalos may break degeneracies among velocity-dependent SIDM models.

Keywords: Milky Way dark matter halo, Computational methods, Galaxy abundances, Dark matter
Pairing of Massive Black Holes in Merger Galaxies Driven by Dynamical Friction. Motivated by observational searches for massive black hole (MBH) pairs at kiloparsec separations we develop a semianalytic model to describe their orbital evolution under the influence of stellar and gaseous dynamical friction (DF). The goal of this study is to determine how the properties of the merger remnant galaxy and the MBHs affect the likelihood and timescale for formation of a close MBH pair with separation of ≲1 pc. We compute approximately 40,000 configurations that cover a wide range of host galaxy properties and investigate their impact on the orbital evolution of unequal mass MBH pairs. We find that the percentage for MBH pairing within a Hubble time is larger than 80% in remnant galaxies with a gas fraction &lt;20% and in galaxies hosting MBH pairs with total mass &gt;106M⊙ and mass ratios ≥1/4. Among these, the remnant galaxies characterized by the fastest formation of close, gravitationally bound MBHs have one or more of the following properties: (1) a large stellar bulge, (2) comparable mass MBHs, and (3) a galactic gas disk rotating close to the circular speed. In such galaxies, the MBHs with the shortest inspiral times, which are likely progenitors of coalescing MBHs, are either on circular prograde orbits or on very eccentric retrograde orbits. Our model also indicates that remnant galaxies with opposite properties, which host slowly evolving MBH pairs, are the most likely hosts of dual active galactic nuclei at kiloparsec separations.

Keywords: AGN host galaxies, Supermassive black holes, Quasars, Active galaxies, Gravitational interaction, Dynamical friction
On the Energy Coupling Efficiency of AGN Outbursts in Galaxy Clusters. Active galactic nucleus (AGN) jets are believed to be important in solving the cooling flow problem in the intracluster medium (ICM), while the detailed mechanism is still under debate. Here we present a systematic study on the energy coupling efficiency ηcp, the fraction of AGN jet energy transferred to the ICM. We first estimate the values of ηcp analytically in two extreme cases, which are further confirmed and extended with a parameter study of spherical outbursts in a uniform medium using hydrodynamic simulations. We find that ηcp increases from ∼0.4 for a weak isobaric injection to ≳0.8 for a powerful point injection. For any given outburst energy, we find two characteristic outburst powers that separate these two extreme cases. We then investigate the energy coupling efficiency of AGN jet outbursts in a realistic ICM with hydrodynamic simulations, finding that jet outbursts are intrinsically different from spherical outbursts. For both powerful and weak jet outbursts, ηcp is typically around 0.7-0.9, partly due to the nonspherical nature of jet outbursts, which produce backflows emanating from the hot spots, significantly enhancing the ejecta-ICM interaction. While for powerful outbursts a dominant fraction of the energy transferred from the jet to the ICM is dissipated by shocks, shock dissipation only accounts for ≲30% of the injected jet energy for weak outbursts. While both powerful and weak outbursts could efficiently heat cooling flows, powerful thermal-energy-dominated jets are most effective in delaying the onset of the central cooling catastrophe.

Keywords: Galaxy clusters, Hydrodynamical simulations, Radio jets, High energy astrophysics, Hydrodynamics, Active galaxies, Low-luminosity active galactic nuclei, Active galactic nuclei, Radio active galactic nuclei, Intracluster medium, Astronomical simulations
Thermodynamic and Energetic Limits on Continental Silicate Weathering Strongly Impact the Climate and Habitability of Wet, Rocky Worlds. The "liquid water habitable zone" (HZ) concept is predicated on the ability of the silicate weathering feedback to stabilize climate across a wide range of instellations. However, representations of silicate weathering used in current estimates of the effective outer edge of the HZ accounts for neither the thermodynamic limit on the concentration of weathering products in runoff set by clay precipitation nor the energetic limit on precipitation set by planetary instellation. We find that when the thermodynamic limit is included in an idealized coupled climate/weathering model, the steady-state planetary climate loses sensitivity to silicate dissolution kinetics, becoming sensitive to temperature primarily through the effect of temperature on runoff and to ${\mathrm{pCO}}_{2}$ through an effect on solute concentration mediated by pH. This increases sensitivity to land fraction, ${\mathrm{CO}}_{2}$ outgassing, and geological factors such as soil age and lithology, all of which are found to have a profound effect on the position of the effective outer edge of the HZ. The interplay between runoff sensitivity and the energetic limit on precipitation leads to novel warm states in the outer reaches of the HZ, owing to the decoupling of temperature and precipitation. We discuss strategies for detecting the signature of the silicate weathering feedback through exoplanet observations in light of insights derived from the revised picture of weathering.

Keywords: Exoplanet evolution, Habitable zone, Habitable planets, Exoplanet atmospheres
The Rise and Fall of the King: The Correlation between FO Aquarii's Low States and the White Dwarf's Spin-down. The intermediate polar FO Aquarii (FO Aqr) experienced its first reported low-accretion states in 2016, 2017, and 2018, and, using newly available photographic plates, we identify prediscovery low states in 1965, 1966, and 1974. The primary focus of our analysis, however, is an extensive set of time-series photometry obtained between 2002 and 2018, with particularly intensive coverage of the 2016-2018 low states. After computing an updated spin ephemeris for the white dwarf (WD), we show that its spin period began to increase in 2014 after having spent 27 yr decreasing; no other intermediate polar has experienced a sign change of its period derivative, but FO Aqr has now done so twice. Our central finding is that the recent low states all occurred shortly after the WD began to spin down, even though no low states were reported in the preceding quarter-century, when it was spinning up. Additionally, the system's mode of accretion is extremely sensitive to the mass-transfer rate, with accretion being almost exclusively disk-fed when FO Aqr is brighter than V ∼ 14 and substantially stream-fed when it is not. Even in the low states, a grazing eclipse remains detectable, confirming the presence of a disklike structure (but not necessarily a Keplerian accretion disk). We relate these various observations to theoretical predictions that during the low state, the system's accretion disk dissipates into a non-Keplerian ring of diamagnetic blobs. Finally, a new XMM-Newton observation from a high state in 2017 reveals an anomalously soft X-ray spectrum and diminished X-ray luminosity compared to pre-2016 observations.

Keywords: DQ Herculis stars, Cataclysmic variable stars, White dwarf stars, Stellar magnetic fields