adsabs/SciX_UAT_keywords huggingface dataset:
Catastrophic Cooling in Superwinds. III. Nonequilibrium Photoionization

Observations of some starburst-driven galactic superwinds suggest that strong radiative cooling could play a key role in the nature of feedback and the formation of stars and molecular gas in star-forming galaxies. These catastrophically cooling superwinds are not adequately described by adiabatic fluid models, but they can be reproduced by incorporating nonequilibrium radiative cooling functions into the fluid model. In this work, we have employed the atomic and cooling module MAIHEM implemented in the framework of the FLASH hydrodynamics code to simulate the formation of radiatively cooling superwinds as well as their corresponding nonequilibrium ionization (NEI) states for various outflow parameters, gas metallicities, and ambient densities. We employ the photoionization program CLOUDY to predict radiation- and density-bounded photoionization for these radiatively cooling superwinds, and we predict UV and optical line emission. Our nonequilibrium photoionization models built with the NEI states demonstrate the enhancement of C IV, especially in metal-rich, catastrophically cooling outflows, and O VI in metal-poor ones.

Keywords: galactic winds; superbubbles; star forming regions; cooling flows; h ii regions; starburst galaxies; emission line galaxies; lyman-break galaxies; lyman-alpha galaxies
Particle Energization at a High Mach Number Perpendicular Shock: 1D Particle-in-cell Simulations

In this paper, we use a 1D particle-in-cell simulation code to study particle preaccelerations at a high Mach number perpendicular shock. Our simulation results show that almost all of the injected particles can be reflected at the shock front, and then they immediately gyrate back to upstream for a long distance. That facilitates the formation of a large-scale shock foot where they dominate the average velocity of particles and the formation of resultant electric fields with several subareas, unlike a low Mach number shock with fewer reflected particles. In the large-scale shock foot with subareas, these reflected particles can be energized by the motional electric fields and unexpected electrostatic fields, which means they may undergo multiple stages of preacceleration processes when gyrating just before the high Mach number perpendicular shock front with high-intensity particle reflection.

Keywords: shocks; planetary bow shocks; solar coronal mass ejection shocks
Rotational Flows in Solar Coronal Flux Rope Cavities

We present a 2.5D magnetohydrodynamic simulation of a systematically rotating prominence inside its coronal cavity using the open-source MPI-AMRVAC code. Our simulation starts from a nonadiabatic, gravitationally stratified corona, permeated with a sheared arcade magnetic structure. The flux rope (FR) is formed through converging and shearing footpoints driving, simultaneously applying randomized heating at the bottom. The latter induces a left-right asymmetry of temperature and density distributions with respect to the polarity inversion line. This asymmetry drives flows along the loops before the FR formation, which gets converted to net rotational motions upon reconnection of the field lines. As the thermal instability within the FR develops, angular momentum conservation about its axis leads to a systematic rotation of both hot coronal and cold condensed plasma. The initial rotational velocity exceeds 60 km s-1. The synthesized images confirm the simultaneous rotations of the coronal plasma seen in 211 and 193 Å and condensations seen in 304 Å. Furthermore, the formation of the dark cavity is evident in 211 and 193 Å images. Our numerical experiment is inspired by observations of so-called giant solar prominence tornadoes and reveals that asymmetric FR formation can be crucial in triggering rotational motions. We reproduce observed spinning motions inside the coronal cavity, augmenting our understanding of the complex dynamics of rotating prominences.

Keywords: magnetohydrodynamics; solar atmosphere; solar prominences; magnetohydrodynamical simulations; solar activity
Early Universe Physics Insensitive and Uncalibrated Cosmic Standards: Constraints on Ωm and Implications for the Hubble Tension

To further gain insight into whether pre-recombination models can resolve the Hubble tension, we explore constraints on the evolution of the cosmic background that are insensitive to early universe physics. The analysis of the CMB anisotropy has been thought to highly rely on early universe physics. However, we show that the fact that the sound horizon at recombination being close to that at the end of the drag epoch is insensitive to early universe physics. This allows us to link the absolute sizes of the two horizons and treat them as free parameters. Jointly, the CMB peak angular size, baryon acoustic oscillations, and Type Ia supernovae can be used as early universe physics insensitive and uncalibrated cosmic standards, which measure the cosmic history from recombination to today. They can set strong and robust constraints on the post-recombination cosmic background, especially the matter density parameter with Ωm = 0.302 ± 0.008 (68% C.L.), assuming a flat Λ cold dark matter universe after recombination. When we combine these with other nonlocal observations, we obtain several constraints on H0 with significantly reduced sensitivity to early universe physics. These are all more consistent with the Planck 2018 result than the local measurement results such as those based on Cepheids. This suggests a tension between the post-recombination, but nonlocal, observations, and the local measurements that cannot be resolved by modifying pre-recombination early universe physics.

Keywords: hubble constant; cosmic microwave background radiation; dark energy; cosmological parameters from large-scale structure; cosmological evolution
Multiple Outflows in the High-mass Cluster-forming Region G25.82-0.17

We present results of continuum and spectral line observations with Atacama Large Millimeter/submillimeter Array (ALMA) and 22 GHz water (H2O) maser observations using the KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry) array (KaVA) toward a high-mass star-forming region, G25.82-0.17. Multiple 1.3 mm continuum sources are revealed, indicating the presence of young stellar objects (YSOs) at different evolutionary stages, namely an ultracompact H II region, G25.82-E, a high-mass young stellar object (HM-YSO), G25.82-W1, and starless cores, G25.82-W2 and G25.82-W3. Two SiO outflows, at N-S and SE-NW orientations, are identified. The CH3OH 8-1-70 E line, known to be a Class I CH3OH maser at 229 GHz, is also detected, showing a mixture of thermal and maser emission. Moreover, the H2O masers are distributed in a region ∼0"25 shifted from G25.82-W1. The CH3OH 224-215 E line shows a compact ringlike structure at the position of G25.82-W1 with a velocity gradient, indicating a rotating disk or envelope. Assuming Keplerian rotation, the dynamical mass of G25.82-W1 is estimated to be >25 M⊙ and the total mass of 20-84 M⊙ is derived from the 1.3 mm continuum emission. The driving source of the N-S SiO outflow is G25.82-W1 while that of the SE-NW SiO outflow is uncertain. Detection of multiple high-mass starless/protostellar cores and candidates without low-mass cores implies that HM-YSOs could form in individual high-mass cores as predicted by the turbulent core accretion model. If this is the case, the high-mass star formation process in G25.82 would be consistent with a scaled-up version of low-mass star formation.

Keywords: star formation; star forming regions; circumstellar disks; stellar jets; astrophysical masers; protostars; young massive clusters; young stellar objects; very long baseline interferometry; radio interferometry
Excitation of Negative Energy Surface Magnetohydrodynamic Waves in an Incompressible Cylindrical Plasma

Negative energy wave (NEW) phenomena may appear in shear flows in the presence of a wave decay mechanism and external energy supply. We study the appearance of negative energy surface waves in a plasma cylinder in the incompressible limit. The cylinder is surrounded by an axial magnetic field and by a plasma of different density. Considering flow inside and viscosity outside the flux tube, we derive dispersion relations and obtain analytical solutions for the phase speed and growth rate (increment) of the waves. It is found that the critical speed shear for the occurrence of the dissipative instability associated with NEWs and the threshold of Kelvin-Helmholtz instability (KHI) depend on the axial wavelength. The critical shear for the appearance of sausage NEW is lowest for the longest axial wavelengths, while for kink waves the minimum value of the critical shear is reached for the axial wavelength comparable to the diameter of the cylinder. The range between the critical speed of the dissipative instability and the KHI threshold is shown to depend on the difference of the Alfvén speeds inside and outside of the cylinder. For all axial wavenumbers, NEW appears for the shear flow speeds lower than the KHI threshold. It is easier to excite NEW in an underdense cylinder than in an overdense one. The negative energy surface waves can be effectively generated for an azimuthal number m = 0 with a large axial wavenumber and for higher modes (m > 0) with a small axial wavenumber.

Keywords: the sun; magnetohydrodynamics
The Volume-complete Sample of M Dwarfs with Masses 0.1 ≤ M/M⊙ ≤ 0.3 within 15 Parsecs

M dwarfs with masses 0.1 ≤ M/M⊙ ≤ 0.3 are under increasing scrutiny because these fully convective stars pose interesting astrophysical questions regarding their magnetic activity and angular momentum history. They also afford the most accessible near future opportunity to study the atmospheres of terrestrial planets. Because they are intrinsically low in luminosity, the identification of the nearest examples of these M dwarfs is essential for progress. We present the volume-complete, all-sky list of 512 M dwarfs with masses 0.1 ≤ M/M⊙ ≤ 0.3 and with trigonometric distances placing them within 15 pc (πtrig ≥ 66.67 mas) from which we have created a sample of 413 M dwarfs for spectroscopic study. We present the mass function for these 512 M dwarfs, which increases with decreasing stellar mass in linear mass space, but is flat in logarithmic mass space. As part of this sample, we present new VJRKCIKC photometry for 17 targets, measured as a result of the RECONS group's long-term work at the CTIO/SMARTS 0.9 m telescope. We also note the details of targets that are known to be members of multiple systems and find a preliminary multiplicity rate of 21% ± 2% for the primary M dwarfs in our sample when considering known stellar and brown dwarf companions at all separations from their primaries. We further find that 43 ± 2% of all M dwarfs with masses 0.1 ≤ M/M⊙ ≤ 0.3 are found in multiple systems with primary stars of all masses within 15 pc.

Keywords: low mass stars; stellar populations; m dwarf stars; solar neighborhood
A Comparison between Nuclear Ring Star Formation in LIRGs and in Normal Galaxies with the Very Large Array

Nuclear rings are excellent laboratories for studying intense star formation. We present results from a study of nuclear star-forming rings in five nearby normal galaxies from the Star Formation in Radio Survey (SFRS) and four local LIRGs from the Great Observatories All-sky LIRG Survey at sub-kiloparsec resolutions using Very Large Array high-frequency radio continuum observations. We find that nuclear ring star formation (NRSF) contributes 49%-60% of the total star formation of the LIRGs, compared to 7%-40% for the normal galaxies. We characterize a total of 57 individual star-forming regions in these rings, and find that with measured sizes of 10-200 pc, NRSF regions in the LIRGs have star formation rate (SFR) and ΣSFR up to 1.7 M⊙ yr-1 and 402 M⊙ yr-1 kpc-2, respectively, which are about 10 times higher than in NRSF regions in the normal galaxies with similar sizes, and comparable to lensed high-z star-forming regions. At ~100-300 pc scales, we estimate low contributions (<50%) of thermal free-free emission to total radio continuum emission at 33 GHz in the NRSF regions in the LIRGs, but large variations possibly exist at smaller physical scales. Finally, using archival sub-kiloparsec resolution CO (J = 1-0) data of nuclear rings in the normal galaxies and NGC 7469 (LIRG), we find a large scatter in gas depletion times at similar molecular gas surface densities, which tentatively points to a multimodal star formation relation on sub-kiloparsec scales.

Keywords: luminous infrared galaxies; galaxy structure; radio continuum emission; galaxy nuclei
On the Production of Polyols and Hydroxycarboxylic Acids in Interstellar Analogous Ices of Methanol

This laboratory work studied the production of complex organic molecules in pure methanol (CH3OH) ices exposed to ionizing radiation in the form of energetic electrons. The chemical evolution of the ices during the electron irradiation at 10 K and subsequent warm-up phase to 300 K was monitored online and in situ via Fourier Transform Infrared spectrometry. Polyols and hydroxycarboxylic acids related absorptions were observed in the infrared spectra of the irradiated ices and residues at room temperature. The residues were analyzed via two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS). Four polyols and five hydroxycarboxylic acids were detected. All of these compounds, except 1, 3-propanediol and 1, 3-butanediol, have been identified in the Murchison and Bell meteorites. The most abundant species, ethylene glycol, has also been found in the interstellar medium (ISM). Our findings suggest that other polyols and acids may also be present in methanol-rich star-forming regions. The non-detection of higher order sugars, such as those found in the ultraviolet photon-processed, 13C-methanol (13CH3OH):water (H2O):ammonia (NH3), and 13CH3OH: H2O ice mixtures, indicates that the type of radiation source or more likely the prevalent NH3 and/or H2O molecules in the ISM are critical to the abiotic formation of the bio-essential sugars. Experiments are currently being designed to elucidate the roles of each component.

Keywords: laboratory astrophysics; astrochemistry; pre-biotic astrochemistry; meteorite composition; interstellar medium
ALMA [{N} {II}] 205 μm Imaging Spectroscopy of the Lensed Submillimeter Galaxy ID 141 at Redshift 4.24

We present an Atacama Large Millimeter/submillimeter Array observation of the Submillimeter galaxy ID 141 at z = 4.24 in the [N II] 205 μm line (hereafter [N II] ) and the underlying continuum at (rest-frame) 197.6 μm. Benefiting from lensing magnification by a galaxy pair at z = 0.595, ID 141 is one of the brightest $z\gt 4$ SMGs. At the angular resolutions of $\sim 1\buildrel{\prime\prime}\over{.} 2$ -1"5 (1″ ∼6.9 kpc), our observation clearly separates and moderately resolves the two lensed images in both continuum and line emission at a signal-to-noise ratio >5. Our continuum-based lensing model implies an averaged amplification factor of ∼5.8 and reveals that the delensed continuum image has a Sérsic index $\simeq 0.95$ and Sérsic radius of ∼0"18 (∼1.24 kpc). Furthermore, the reconstructed [N II] velocity field in the source plane is dominated by a rotation component with a maximum velocity of ∼300 km s-1 at large radii, indicating a dark matter halo mass of ∼10 ${}^{12}{M}_{\odot }$ . This, together with the reconstructed velocity dispersion field being smooth and modest in value (<100 km s-1) over much of the outer parts of the galaxy, favors the interpretation of ID 141 being a disk galaxy dynamically supported by rotation. The observed [N II] /CO (7-6) and [N II] /[C II] 158 μm line-luminosity ratios, which are consistent with the corresponding line ratio versus far-infrared color correlation from local luminous infrared galaxies, imply a delensed star formation rate of (1.8 $\pm \,0.6)\times {10}^{3}{M}_{\odot }$ yr-1 and provide an independent estimate of the size of the star-forming region ${0.7}_{-0.3}^{+0.3}$ kpc in radius.

Keywords: far infrared interferometry; strong gravitational lensing; infrared galaxies; high-redshift galaxies; submillimeter astronomy; starburst galaxies; dust continuum emission
On the Fast Radio Burst and Persistent Radio Source Populations

The first fast radio burst (FRB) to be precisely localized was associated with a luminous persistent radio source (PRS). Recently, a second FRB/PRS association was discovered for another repeating source of FRBs. However, it is not clear what makes FRBs or PRS or how they are related. We compile FRB and PRS properties to consider the population of FRB/PRS sources. We suggest a practical definition for PRS as FRB associations with luminosity greater than 1029 erg s-1 Hz-1 that are not attributed to star formation activity in the host galaxy. We model the probability distribution of the fraction of FRBs with PRS for repeaters and nonrepeaters, showing there is not yet evidence for repeaters to be preferentially associated with PRS. We discuss how FRB/PRS sources may be distinguished by the combination of active repetition and an excess dispersion measure local to the FRB environment. We use CHIME/FRB event statistics to bound the mean per-source repetition rate of FRBs to be between 25 and 440 yr-1. We use this to provide a bound on the density of FRB-emitting sources in the local universe of between 2.2 × 102 and 5.2 × 104 Gpc-3 assuming a pulsar-like beamwidth for FRB emission. This density implies that PRS may comprise as much as 1% of compact, luminous radio sources detected in the local universe. The cosmic density and phenomenology of PRS are similar to that of the newly discovered, off-nuclear "wandering" active galactic nuclei (AGN). We argue that it is likely that some PRS have already been detected and misidentified as AGN.

Keywords: magnetars; radio bursts; radio source counts
ASASSN-15hy: An Underluminous, Red 03fg-like Type Ia Supernova

We present photometric and spectroscopic observations of the 03fg-like Type Ia supernova (SN Ia) ASASSN-15hy from the ultraviolet (UV) to the near-infrared (NIR). ASASSN-15hy shares many of the hallmark characteristics of 03fg-like SNe Ia, previously referred to as "super-Chandrasekhar" SNe Ia. It is bright in the UV and NIR, lacks a clear i-band secondary maximum, shows a strong and persistent C II feature, and has a low Si II λ6355 velocity. However, some of its properties are also extreme among the subgroup. ASASSN-15hy is underluminous (MB,peak = $-{19.14}_{-0.16}^{+0.11}$ mag), red ( ${(B-V)}_{B\max }={0.18}_{-0.03}^{+0.01}$ mag), yet slowly declining (Δm15(B) = 0.72 ± 0.04 mag). It has the most delayed onset of the i-band maximum of any 03fg-like SN. ASASSN-15hy lacks the prominent H-band break emission feature that is typically present during the first month past maximum in normal SNe Ia. Such events may be a potential problem for high-redshift SN Ia cosmology. ASASSN-15hy may be explained in the context of an explosion of a degenerate core inside a nondegenerate envelope. The explosion impacting the nondegenerate envelope with a large mass provides additional luminosity and low ejecta velocities. An initial deflagration burning phase is critical in reproducing the low 56Ni mass and luminosity, while the large core mass is essential in providing the large diffusion timescales required to produce the broad light curves. The model consists of a rapidly rotating 1.47 M⊙ degenerate core and a 0.8 M⊙ nondegenerate envelope. This "deflagration core-degenerate" scenario may result from the merger between a white dwarf and the degenerate core of an asymptotic giant branch star.

Keywords: white dwarf stars; type ia supernovae; supernovae
JWST/NIRCam Coronagraphy of the Young Planet-hosting Debris Disk AU Microscopii

High-contrast imaging of debris disk systems permits us to assess the composition and size distribution of circumstellar dust, to probe recent dynamical histories, and to directly detect and characterize embedded exoplanets. Observations of these systems in the infrared beyond 2-3 μm promise access to both extremely favorable planet contrasts and numerous scattered-light spectral features-but have typically been inhibited by the brightness of the sky at these wavelengths. We present coronagraphy of the AU Microscopii (AU Mic) system using JWST's Near Infrared Camera (NIRCam) in two filters spanning 3-5 μm. These data provide the first images of the system's famous debris disk at these wavelengths and permit additional constraints on its properties and morphology. Conducting a deep search for companions in these data, we do not identify any compelling candidates. However, with sensitivity sufficient to recover planets as small as ~0.1 Jupiter masses beyond ~2″ (~20 au) with 5σ confidence, these data place significant constraints on any massive companions that might still remain at large separations and provide additional context for the compact, multiplanet system orbiting very close-in. The observations presented here highlight NIRCam's unique capabilities for probing similar disks in this largely unexplored wavelength range, and they provide the deepest direct imaging constraints on wide-orbit giant planets in this very well-studied benchmark system.

Keywords: exoplanet systems; direct imaging; debris disks; coronagraphic imaging; m dwarf stars
Cooling Models for the Most Massive White Dwarfs

We present a set of ultramassive white dwarf models, focused on masses above 1.3 M⊙. Given the uncertainties about the formation and compositions of such objects, we construct parameterized model sequences, guided by evolutionary calculations including both single star and double white dwarf merger formation channels. We demonstrate that the cooling of objects with central densities in excess of 109 g cm-3 is dominated by neutrino cooling via the Urca process in the first ≈100 Myr after formation. Our models indicate that the recently discovered ultramassive white dwarf ZTF J190132.9+145808.7 is likely to have experienced this Urca-dominated cooling regime. We also show that the high densities imply that diffusion is unlikely to significantly alter the core compositions of these objects before they crystallize.

Keywords: white dwarf stars; stellar evolutionary models; stellar mergers
Helium Line Emissivities in the Solar Corona

We present new collisional-radiative models (CRMs) for helium in the quiescent solar corona and predict the emissivities of the He and He+ lines to be observed by DKIST, Solar Orbiter, and Proba-3. We discuss in detail the rates we selected for these models, highlighting several shortcomings we have found in previous work. As no previous complete and self-consistent coronal CRM for helium existed, we have benchmarked our largest model at a density of 106 cm-3 and temperature of 20,000 K against recent CRMs developed for photoionized nebulae. We then present results for the outer solar corona, using new dielectronic recombination rates we have calculated, which increase the abundance of neutral helium by about a factor of 2. We also find that all optical triplet He I lines, and in particular the well-known He I 10830 and 5876 Å lines, are strongly affected by both photoexcitation and photoionization from the disk radiation and that extensive CRMs are required to obtain correct estimates. Close to the Sun, at an electron density of 108 cm-3 and temperature of 1 MK, we predict the emissivity of He I 10830 Å to be comparable to that of the strong Fe XIII coronal line at 10798 Å. However, we expect the He I emissivity to sharply fall in the outer corona, with respect to Fe XIII. We confirm that the He+ Lyα at 304 Å is also significantly affected by photoexcitation and is expected to be detectable as a strong coronal line up to several solar radii.

Keywords: radiative processes; solar radiation; quiet solar corona; solar coronal lines; atomic physics; dielectronic recombination; photoionization; transition probabilities; electron impact ionization