adsabs/SciX_UAT_keywords huggingface dataset:
The Sandwich Mode for Vertical Shear Instability in Protoplanetary Disks

Turbulence has a profound impact on the evolution of gas and dust in protoplanetary disks (PPDs), from driving the collisions and the diffusion of dust grains, to the concentration of pebbles in giant vortices, thus, facilitating planetesimal formation. The vertical shear instability (VSI) is a hydrodynamic mechanism, operating in PPDs if the local rate of thermal relaxation is high enough. Previous studies of the VSI have, however, relied on the assumption of constant cooling rates, or neglected the finite coupling time between the gas particles and the dust grains. Here, we present the results of hydrodynamic simulations of PPDs with the PLUTO code that include a more realistic thermal relaxation prescription, which enables us to study the VSI in the optically thick and optically thin parts of the disk under consideration of the thermal dust-gas coupling. We show the VSI to cause turbulence even in the optically thick inner regions of PPDs in our two- and three-dimensional simulations. The collisional decoupling of dust and gas particles in the upper atmosphere and the correspondingly inefficient thermal relaxation rates lead to the damping of the VSI turbulence. Long-lived anticyclonic vortices form in our three-dimensional simulation. These structures emerge from the turbulence in the VSI-active layer, persist over hundreds of orbits and extend vertically over the whole extent of the turbulent region. We conclude that the VSI leads to turbulence and the formation of long-lived dust traps within ±3 pressure scale heights distance from the disk midplane.

Keywords: protoplanetary disks; hydrodynamical simulations; accretion; planet formation
New Limits on Axionic Dark Matter from the Magnetar PSR J1745-2900

Axions are a promising dark matter candidate that were motivated to solve the strong charge-parity problem and that may also address the cosmological matter-antimatter asymmetry. Axion-photon conversion is possible in the presence of the strong magnetic fields, and the photon so produced will have energy equal to the axion mass. Here we report new limits on axionic dark matter obtained from radio spectra of the Galactic Center magnetar PSR J1745-2900. The magnetar has a magnetic field of 1.6 × 1014 G that interacts with a dark matter density 2 × 105 to 2 × 109 times greater than the local dark matter encountered by terrestrial haloscopes, depending on the Galactic dark matter profile. No significant spectral features are detected across 62% of the axion mass range 4.1-165.6 μeV (1-40 GHz). The interpretation of flux limits into limits on the two-photon coupling strength gaγγ depends on the magnetospheric conversion model and on the dark matter density at the Galactic Center. For a standard dark matter profile, we exclude axion models with gaγγ > 6-34 ×10-12 GeV-1 with 95% confidence over the mass ranges 4.2-8.4, 8.9-10.0, 12.3-16.4, 18.6-26.9, 33.0-62.1, 70.1-74.3, 78.1-80.7, 105.5-109.6, 111.6-115.2, 126.0-159.3, and 162.5-165.6 μeV. For the maximal dark matter cusp allowed by stellar orbits near Sgr A*, these limits reduce to gaγγ > 6-34 × 10-14 GeV-1, which exclude some theoretical models for masses >33 μeV. Limits may be improved by modeling stimulated axion conversion, by ray-tracing conversion pathways in the magnetar magnetosphere, and by obtaining deeper broad-band observations of the magnetar.

Keywords: dark matter; navarro-frenk-white profile; particle physics; magnetars; neutron stars
Multimessenger Diagnostics of the Engine behind Core-collapse Supernovae

Core-collapse supernova explosions play a wide role in astrophysics by producing compact remnants (neutron stars or black holes) and the synthesis and injection of many heavy elements into their host galaxy. Because they are produced in some of the most extreme conditions in the universe, they can also probe physics in extreme conditions (matter at nuclear densities and extreme temperatures and magnetic fields). To quantify the impact of supernovae on both fundamental physics and our understanding of the universe, we must leverage a broad set of observables of this engine. In this paper, we study a subset of these probes using a suite of one-dimensional, parameterized mixing models: ejecta remnants from supernovae, ultraviolet, optical and infrared light curves, and transient gamma-ray emission. We review the other diagnostics and show how the different probes tie together to provide a more clear picture of the supernova engine. Join us in improving and evolving this document through active community engagement. Instructions are provided at this link: https://github.com/clfryer/MM-SNe.

Keywords: type ii supernovae; supernova neutrinos; supernova remnants; gravitational wave sources; x-ray sources; gamma-ray sources; dust formation; dust destruction
CECILIA: Direct O, N, S, and Ar Abundances in Q2343-D40, a Galaxy at z ∼ 3

Measurements of chemical abundances in high-z star-forming (SF) galaxies place important constraints on the enrichment histories of galaxies and the physical conditions in the early Universe. The James Webb Space Telescope (JWST) is beginning to enable direct chemical abundance measurements in galaxies at z > 2 via the detection of the faint T e -sensitive auroral line [O III] λ4364. However, abundances of other elements (e.g., S and Ar) in high-z galaxies remain unconstrained owing to a lack of T e data and wavelength coverage. Here we present multiple direct abundances in Q2343-D40, a galaxy at z = 2.9628 ± 0.0001 observed with JWST/NIRSpec as part of the CECILIA program. We report the first simultaneous measurement of T e [O III] and T e [S III] in a high-z galaxy, finding good agreement with the temperature trends in local SF systems. We measure a gas-phase metallicity of 12+log(O/H) = 8.07 ± 0.06, and the N/O abundance, log(N/O) = ‑1.37 ± 0.21, is indicative of primary nucleosynthesis. The S/O and Ar/O relative abundances, log(S/O) = ‑1.88 ± 0.10 and log(Ar/O) = ‑2.80 ± 0.12, are both >0.3 dex lower than the solar ratios. However, the relative Ar2+/S2+ abundance is consistent with the solar ratio, suggesting that the relative S-to-Ar abundance does not evolve significantly with redshift. Recent nucleosynthesis models find that significant amounts of S and Ar are produced in Type Ia supernovae, such that the S/O and Ar/O abundances in Q2343-D40 could be the result of predominantly core-collapse supernova enrichment. Future JWST observations of high-z galaxies will uncover whether S/O and Ar/O are sensitive to the timescales of these different enrichment mechanisms.

Keywords: high-redshift galaxies; emission line galaxies; chemical abundances; galaxy spectroscopy
A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ∼ 12 Galaxy in Early JWST CEERS Imaging

We report the discovery of a candidate galaxy with a photo-z of z ~ 12 in the first epoch of the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following conservative selection criteria, we identify a source with a robust z phot = ${11.8}_{-0.2}^{+0.3}$ (1σ uncertainty) with m F200W = 27.3 and ≳7σ detections in five filters. The source is not detected at λ < 1.4 μm in deep imaging from both Hubble Space Telescope (HST) and JWST and has faint ~3σ detections in JWST F150W and HST F160W, which signal a Lyα break near the red edge of both filters, implying z ~ 12. This object (Maisie's Galaxy) exhibits F115W - F200W > 1.9 mag (2σ lower limit) with a blue continuum slope, resulting in 99.6% of the photo-z probability distribution function favoring z > 11. All data-quality images show no artifacts at the candidate's position, and independent analyses consistently find a strong preference for z > 11. Its colors are inconsistent with Galactic stars, and it is resolved (r h = 340 ± 14 pc). Maisie's Galaxy has log M */M ⊙ ~ 8.5 and is highly star-forming (log sSFR ~ -8.2 yr-1), with a blue rest-UV color (β ~ -2.5) indicating little dust, though not extremely low metallicity. While the presence of this source is in tension with most predictions, it agrees with empirical extrapolations assuming UV luminosity functions that smoothly decline with increasing redshift. Should follow-up spectroscopy validate this redshift, our universe was already aglow with galaxies less than 400 Myr after the Big Bang.

Keywords: early universe; galaxy formation; galaxy evolution
A Theoretical Investigation of the Magnetic-field-induced Transition in Fe X, of Importance for Measuring Magnetic Field Strengths in the Solar Corona

The use of the magnetic-field-induced transition (MIT) $3{{\rm{p}}}^{4}3{\rm{d}}{}^{4}{D}_{7/2}\to 3{{\rm{p}}}^{5}\,{}^{2}{P}_{3/2}^{{\rm{o}}}$ in Fe X for the measurement of the magnetic field strength in the solar corona has been discussed and demonstrated in a number of recent studies. This diagnostic technique depends on, among other conditions, the accuracy of the atomic data for Fe X. In the present work, we carry out a large-scale calculation for the atomic properties needed for the determination of the MIT rate using the multiconfiguration Dirac-Hartree-Fock method. Four computational schemes are employed to study the convergence of the atomic properties of interest. Comparison with other experimental and theoretical sources are performed and recommended values are suggested for important properties, e.g., the magnetic induced transition probabilities as a function of magnetic field strengths. The present calculations affect magnetic field measurements by decreasing the magnetic field strengths by 10%-15%, leading to differences in magnetic energy up to 30%. We recommend that the current data should be employed in magnetic field measurements in the future.

Keywords: solar magnetic fields
The Bulk Flow Velocity and Acceleration of the Inner Jet in M87

A high sensitivity, 7 mm Very Long Baseline Array image of M87 is analyzed in order to estimate the jet velocity within 0.65 mas of the point of origin. The image captured a high signal-to-noise, double-ridged, counter-jet extending ~1 mas from the nucleus. After defining conditions and requirements that justify approximate time averaged bilateral symmetry, a continuous set of Lorentz transformations are found that map the double-ridged counter-jet intensity profile into the double-ridged jet intensity profile. The mapping is realized by a uniformly accelerating flow with intrinsic velocity of ~0.27c at 0.4 mas (a de-projected distance of 0.38 lt-yr) to 0.38c at 0.65 mas (a de-projected distance of 0.61 lt-yr) from the nucleus. Since the velocity field is derived from the global surface brightness profile and does not depend on the motion of enhanced features, it is most likely a bulk flow velocity as opposed to a pattern velocity. This interpretation is corroborated by the fact that the distribution of the apparent velocities of previously identified individual features (from the literature) within 0.65 mas of the nucleus are consistent with local hydrodynamic shocks being advected with the local bulk flow velocity. The bulk flow velocity of the visible inner jet is a constraint that can potentially break degeneracies between numerical simulations that are designed to replicate both the annulus that was imaged by the Event Horizon Telescope as well as the base of the inner jet.

Keywords: relativistic jets; radio jets
On the Transition Stage of Pulsar Pulsed Radio Emission and Its Potential Association with Radio Pulsar Nulling

While the precise mechanism of generating pulsed coherent radio emission from pulsars remains elusive, certain gap-invoking models (especially, the inner gap model) offer a comprehensive and plausible explanation for the genesis and termination of such emissions. However, the transition stage between the period of persistent radio emission and the period of radio-quiet emission remains poorly understood, despite observations indicating that a radio pulsar in the pulse-nulling state is undergoing the transition stage. In this study, we present a qualitative explanation for the elusive transition stage by modeling pulsar magnetospheres analytically as equivalent resistive–capacitive circuits based on the inner gap model. Our result indicates that, due to lengthy spin-down, older radio pulsars will gradually shift from the state of persistent radio emission to a certain type of pulse-nulling state by delayed sparks within their inner gaps.

Keywords: pulsars; radio astronomy; radio pulsars
The Effect of Seafloor Weathering on Planetary Habitability

Conventionally, a habitable planet is one that can support liquid water on its surface. Habitability depends on temperature, which is set by insolation and the greenhouse effect, due mainly to CO2 and water vapor. The CO2 level is increased by volcanic outgassing and decreased by continental and seafloor weathering. Here, I examine the climate evolution of Earth-like planets using a globally averaged climate model that includes both weathering types. Climate is sensitive to the relative contributions of continental and seafloor weathering, even when the total weathering rate is fixed. Climate also depends strongly on the dependence of seafloor weathering on CO2 partial pressure. Both these factors are uncertain. Earth-like planets have two equilibrium climate states: (I) an ice-free state where outgassing is balanced by both weathering types, and (II) an ice-covered state where outgassing is balanced by seafloor weathering alone. The second of these has not been explored in detail before. For some planets, neither state exists, and the climate cycles between ice-covered and ice-free states. For some other planets, both equilibria exist, and the climate depends on the initial conditions. Insolation increases over time due to stellar evolution, so a planet usually encounters the ice-covered equilibrium first. Such a planet will remain ice covered, even if the ice-free state appears subsequently, unless the climate receives a large perturbation. The ice-covered equilibrium state covers a large fraction of phase space for Earth-like planets. Many planets conventionally assigned to a star's habitable zone may be rendered uninhabitable as a result.

Keywords: habitable planets; habitable zone; earth (planet); land-atmosphere interactions; ocean-atmosphere interactions; astrobiology
Transport of Charged Particles Propagating in Turbulent Magnetic Fields as a Red-noise Process

The transport of charged particles in various astrophysical environments permeated by magnetic fields is described in terms of a diffusion process, which relies on diffusion-tensor parameters generally inferred from Monte Carlo simulations. In this paper, a theoretical derivation of the diffusion coefficient in the case of a purely turbulent magnetic field is presented. The approach is based on a red-noise approximation to model the 2 point correlation function of the magnetic field experienced by the particles between two successive times. This approach is shown to describe the regime in which the Larmor radius of the particles is in resonance with the wavelength power spectrum of the turbulence (gyroresonant regime), extending hence previous results applying to the high-rigidity regime in which the Larmor radius is greater than the larger wavelength of the turbulence. The results are shown to be consistent with those obtained with a Monte Carlo generator. Although not considered in this study, the presence of a mean field on top of the turbulence is discussed.

Keywords: cosmic rays; magnetic fields; interplanetary turbulence
Binary Formation in a 100 μm Dark Massive Core

We report high-resolution ALMA observations toward a massive protostellar core C1-Sa (~30 M ⊙) in the Dragon infrared dark cloud. At the resolution of 140 au, the core fragments into two kernels (C1-Sa1 and C1-Sa2) with a projected separation of ~1400 au along the elongation of C1-Sa, consistent with a Jeans length scale of ~1100 au. Radiative transfer modeling using RADEX indicates that the protostellar kernel C1-Sa1 has a temperature of ~75 K and a mass of 0.55 M ⊙. C1-Sa1 also likely drives two bipolar outflows, one being parallel to the plane of the sky. C1-Sa2 is not detected in line emission and does not show any outflow activity but exhibits ortho-H2D+ and N2D+ emission in its vicinity; thus it is likely still starless. Assuming a 20 K temperature, C1-Sa2 has a mass of 1.6 M ⊙. At a higher resolution of 96 au, C1-Sa1 begins to show an irregular shape at the periphery, but no clear sign of multiple objects or disks. We suspect that C1-Sa1 hosts a tight binary with inclined disks and outflows. Currently, one member of the binary is actively accreting while the accretion in the other is significantly reduced. C1-Sa2 shows hints of fragmentation into two subkernels with similar masses, which requires further confirmation with higher sensitivity.

Keywords: star formation; star forming regions; infrared dark clouds; molecular clouds; protostars; interstellar medium; astrochemistry; binary stars; multiple stars; stellar jets; massive stars; stellar accretion
Dissipative Instability of Magnetohydrodynamic Sausage Waves in a Compressional Cylindrical Plasma: Effect of Flow Shear and Viscosity Shear

The shear flow influences the stability of magnetohydrodynamic (MHD) waves. In the presence of a dissipation mechanism, flow shear may induce an MHD wave instability below the threshold of the Kelvin-Helmholtz instability, which is called dissipative instability. This phenomenon is also called negative energy wave instability because it is closely related to the backward wave, which has negative wave energy. Considering viscosity as a dissipation mechanism, we derive an analytical dispersion relation for the slow sausage modes in a straight cylinder with a discontinuous boundary. It is assumed that the steady flow is inside and dynamic and bulk viscosities are outside the circular flux tube under photospheric condition. When the two viscosities are weak, it is found that for the slow surface mode, the growth rate is proportional to the axial wavenumber and flow shear, consistent within the incompressible limit. For a slow body mode, the growth rate has a peak at a certain axial wavenumber, and its order of magnitude is similar to surface mode. The linear relationship between the growth rate and the dynamic viscosity established in the incompressible limit develops nonlinearly when the flow shear and/or the two viscosities are sufficiently strong.

Keywords: solar photosphere; solar oscillations; magnetohydrodynamics
Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. VII. Energy Equipartition

We examine the degree of energy equipartition in nine Galactic globular clusters using proper motions measured with the Hubble Space Telescope. For most clusters in the sample, this is the first energy equipartition study ever performed. This study is also the largest of its kind, albeit with only nine clusters. We begin by rigorously cleaning the catalogs to remove poor-quality measurements and to ensure high signal to noise for the study. Using the cleaned catalogs, we investigate how velocity dispersion σ changes with stellar mass m. We fit two functional forms: the first, a classic power law of the form σ ∝ m -η where η is the degree of energy equipartition, and the second from Bianchini et al. parameterized by an equipartition mass m eq where η changes with stellar mass. We find that both functions fit well but cannot distinguish with statistical significance which function provides the best fit. All clusters exhibit varying degrees of partial equipartition; no cluster is at or near full equipartition. We search for correlations of η and m eq with various cluster properties. The most significant correlation is observed with the number of core or median relaxation times ( ${N}_{\mathrm{core}}$ or N half) the cluster has experienced. Finally, we determine the radial equipartition profile for each cluster, that is, how the degree of equipartition changes with projected distance from the cluster center. We do not detect statistically significant trends in the degree of equipartition with radius. Overall, our observational findings are in broad agreement with theoretical predictions from N -body models published in recent years.

Keywords: globular star clusters; proper motions; stellar dynamics; stellar kinematics
Precursors of Supernovae from Mass Eruption: Prospects for Early Warning of Nearby Core-collapse Supernovae

Recent observations of a large fraction of Type II supernovae (SNe) show traces of dense circumstellar medium (CSM) very close to the progenitor star. If this CSM is created by eruptive mass loss several months before core collapse, the eruption itself may be visible as a precursor, helpful as an early warning of a near-future SN. Using radiation hydrodynamical simulations based on the open-source code CHIPS, we theoretically model the emission from the mass eruption of a red supergiant star. We find that for a modest mass eruption the luminosity is typically on the order of 1039 erg s-1, can last as long as hundreds of days until the star explodes, and is mainly bright in the infrared (from -9 to -11 mag around peak). We discuss observational strategies to find these signatures from Galactic and local Type II SNe.

Keywords: core-collapse supernovae; type ii supernovae; transient sources; circumstellar matter
Multipoint Turbulence Analysis with HelioSwarm

Exploration of plasma dynamics in space, including turbulence, is entering a new era of multisatellite constellation measurements that will determine fundamental properties with unprecedented precision. Familiar but imprecise approximations will need to be abandoned and replaced with more-advanced approaches. We present a preparatory study of the evaluation of second- and third-order statistics, using simultaneous measurements at many points. Here, for specificity, the orbital configuration of the NASA Swarm mission is employed in conjunction with 3D magnetohydrodynamics numerical simulations of turbulence. The HelioSwarm nine-spacecraft constellation flies virtually through the turbulence to compare results with the exact numerical statistics. We demonstrate novel increment-based techniques for the computation of (1) the multidimensional spectra and (2) the turbulent energy flux. This latter increment-space estimate of the cascade rate, based on the third-order Yaglom-Politano-Pouquet theory, uses numerous increment-space tetrahedra. Our investigation reveals that HelioSwarm will provide crucial information on the nature of astrophysical turbulence.

Keywords: solar wind; interplanetary turbulence
PSR J1953+1844 Probably Being the Descendant of an Ultracompact X-Ray Binary

PSR J1953+1844 (i.e., M71E) is a millisecond pulsar in a 53 minute binary orbit discovered by the Five-hundred-meter Aperture Spherical radio Telescope. The mass function from pulsar timing is 2.3 × 10-7 M ⊙. The possible redback origin of this system has been discussed by Pan et al. We discuss here an alternative evolution track for this binary system, namely that PSR J1953+1844 is a descendant of an ultracompact X-ray binary (UCXB), which has a hydrogen-poor donor accreting onto a neutron star (NS) with an orbital period of ≤1 hr. We noticed that some UCXB systems hold an accreting millisecond X-ray pulsar (AMXP) and a donor with a mass of about 0.01 M ⊙. M71E has a very similar orbit to those of AMXPs, indicating that it might be evolved from a UCXB similar to PSR J1653-0158. The companion star of M71E should be significantly bloated and it most probably has a carbon and oxygen composition, otherwise a low inclination angle of the orbit is required for a helium companion. The discovery of this M71E binary system may shed light on when and how an NS in a UCXB turns into a radio pulsar.

Keywords: binary pulsars; x-ray binary stars; low-mass x-ray binary stars; compact binary stars