Sazuna/UAT_keywords huggingface dataset:
Decomposition of Benzene during Impacts in N<SUB>2</SUB>-dominated Atmospheres. Benzene is a simple neutral aromatic compound found in molecular clouds, comets, and planetary atmospheres. It has been confirmed on Jupiter, Saturn, Titan, and is expected on exoplanets. In this paper, the decomposition of benzene in a simulated asteroid or comet impact into an N2-dominated atmosphere was investigated. The impact plasma was simulated with laser-induced dielectric breakdown and the gas phase decomposition products were observed using high-resolution Fourier transform infrared spectroscopy. The gas phase decomposition products involve mainly HCN, C2H2, and smaller amounts of CH4 with yields of 3.1%-24.0%, 0-11.7%, and 0.5%-3.3%, respectively. Furthermore, in presence of water, benzene also produces CO and CO2 with yields of 2.4%-35.1% and 0.01%-4.8%, respectively. The oxidation state of the product mixture is proportional to the water content. Apart from that, a black-brownish solid phase is formed during the experiments, which makes up about 60% of the original carbon content. Our results therefore show that in anoxic N2-dominated planetary atmospheres, impacts might lead to the depletion of benzene and the formation of HCN, C2H2, and CH4 and, in the presence of water, to the formation of CO and CO2.

Keywords: Infrared spectroscopy, Laboratory astrophysics, Titan, Exoplanet atmospheres, Exoplanet atmospheric evolution
Lagrangian Stochastic Model for the Motions of Magnetic Footpoints on the Solar Wind Source Surface and the Path Lengths of Boundary-driven Interplanetary Magnetic Field Lines. In this work, we extend Leighton's diffusion model describing the turbulent mixing of magnetic footpoints on the solar wind source surface. The present Lagrangian stochastic model is based on the spherical Ornstein-Uhlenbeck process with drift that is controlled by the rotation frequency Ω of the Sun, the Lagrangian integral timescale τ L, and the root-mean-square footpoint velocity V rms. The Lagrangian velocity and the positions of magnetic footpoints on the solar wind source surface are obtained from the solutions of a set of stochastic differential equations, which are solved numerically. The spherical diffusion model of Leighton is recovered in the singular Markov limit when the Lagrangian integral timescale tends to zero while keeping the footpoint diffusivity finite. In contrast to the magnetic field lines driven by standard Brownian processes on the solar wind source surface, the interplanetary magnetic field lines are smooth differentiable functions with finite path lengths in our model. The path lengths of the boundary-driven interplanetary magnetic field lines and their probability distributions at 1 au are computed numerically, and their dependency with respect to the controlling parameters is investigated. The path-length distributions are shown to develop a significant skewness as the width of the distributions increases.

Keywords: Interplanetary turbulence, Interplanetary magnetic fields
Ambipolar Heating of Magnetars. Magnetars, neutron stars thought to be with ultrastrong magnetic fields of 1014-15 G, are observed to be much hotter than ordinary pulsars with ~1012 G, and additional heating sources are required. One possibility is heating by the ambipolar diffusion in the stellar core. This scenario is examined by calculating the models using the relativistic thermal evolutionary code without making the isothermal approximation. The results show that this scenario can be consistent with most of the observed magnetar temperature data.

Keywords: Neutron stars, Magnetars, Degenerate matter, X-ray stars
New Metrics to Probe the Dynamical State of Galaxy Clusters. We present new diagnostic metrics to probe the dynamical state of galaxy clusters. These novel metrics rely on the computation of the power spectra of the matter and gas distributions and their cross-correlation derived from cluster observations. This analysis permits us to cross-correlate the fluctuations in the matter distribution, inferred from high-resolution lensing mass maps derived from Hubble Space Telescope (HST) data, with those derived from the emitted X-ray surface brightness distribution of the hot intracluster medium from the Chandra X-ray Observatory. These methodological tools allow us to quantify with unprecedented resolution the coherence with which the gas traces the mass and interrogate the assumption that the gas is in hydrostatic equilibrium with the underlying gravitational potential. We characterize departures from equilibrium as a function of scale with a new gas-mass coherence parameter. The efficacy of these metrics is demonstrated by applying them to the analysis of two representative clusters known to be in different dynamical states: the massive merging cluster A2744, from the HST Frontier Fields sample, and the dynamically relaxed cluster A383, from the Cluster Lensing and Supernova Survey with the Hubble sample. Using lensing mass maps in combination with archival Chandra data, and simulated cluster analogs available from the OMEGA500 suite, we quantify the fluctuations in the mass and X-ray surface brightness and show that new insights into the dynamical state of the clusters can be obtained from our gas-mass coherence analysis.

Keywords: Dark matter distribution, Observational cosmology, Large-scale structure of the universe
The 2022 High-energy Outburst and Radio Disappearing Act of the Magnetar 1E 1547.0-5408. We report the radio and high-energy properties of a new outburst from the radio-loud magnetar 1E 1547.0-5408. Following the detection of a short burst from the source with Swift-BAT on 2022 April 7, observations by NICER detected an increased flux peaking at (6.0 ± 0.4) × 10-11 erg s-1 cm-2 in the soft X-ray band, falling to a baseline level of 1.7 × 10-11 erg s-1 cm-2 over a 17 day period. Joint spectroscopic measurements by NICER and NuSTAR indicated no change in the hard nonthermal tail despite the prominent increase in soft X-rays. Observations at radio wavelengths with Murriyang, the 64 m Parkes radio telescope, revealed that the persistent radio emission from the magnetar disappeared at least 22 days prior to the initial Swift-BAT detection and was redetected two weeks later. Such behavior is unprecedented in a radio-loud magnetar, and may point to an unnoticed slow rise in the high-energy activity prior to the detected short bursts. Finally, our combined radio and X-ray timing revealed the outburst coincided with a spin-up glitch, where the spin frequency and spin-down rate increased by 0.2 ± 0.1 μHz and (-2.4 ± 0.1) × 10-12 s-2, respectively. A linear increase in the spin-down rate of (-2.0 ± 0.1) × 10-19 s-3 was also observed over 147 days of postoutburst timing. Our results suggest that the outburst may have been associated with a reconfiguration of the quasi-polar field lines, likely signaling a changing twist, accompanied by spatially broader heating of the surface and a brief quenching of the radio signal, yet without any measurable impact on the hard X-ray properties.

Keywords: Neutron stars, High energy astrophysics, Pulsars, Magnetars, Radio pulsars
Constraining the Systematics of (Acoustic) Wave Heating Estimates in the Solar Chromosphere. Acoustic wave heating is believed to contribute significantly to the missing energy input required to maintain the solar chromosphere in its observed state. We studied the propagation of waves above the acoustic cutoff in the upper photosphere into the chromosphere with ultraviolet and optical spectral observations interpreted through comparison with 3D radiative magnetohydrodynamic Bifrost models to constrain the heating contribution from acoustic waves in the solar atmosphere. Sit-and-stare observations taken with the Interface Region Imaging Spectrograph and data from the Interferometric BIdimensional Spectrograph were used to provide the observational basis of this work. We compared the observations with synthetic observables derived from the Bifrost solar atmospheric model. Our analysis of the Bifrost simulations show that internetwork and enhanced-network regions exhibit significantly different wave-propagation properties, which are important for accurate wave flux estimates. The inferred wave energy fluxes based on our observations are not sufficient to maintain the solar chromosphere. We point out that the systematics of the modeling approaches in the literature lead to differences which could determine the conclusions of this type of study, based on the same observations.

Keywords: Solar chromospheric heating, Radiative transfer, Quiet solar chromosphere
Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes. Recent studies have indicated that the ratio between half-mass and half-light radii, r mass/r light, varies significantly as a function of stellar mass and redshift, complicating the interpretation of the ubiquitous r light - M * relation. To investigate, in this study we construct the light and color profiles of ~3000 galaxies at 1 &lt; z &lt; 2 with $\mathrm{log}{M}_{* }/{M}_{\odot }\gt 10.25$ using imcascade, a Bayesian implementation of the Multi-Gaussian Expansion (MGE) technique. imcascade flexibly represents galaxy profiles using a series of Gaussians, free of any a priori parameterization. We find that both star-forming and quiescent galaxies have, on average, negative color gradients. For star-forming galaxies, we find steeper gradients that evolve with redshift and correlate with dust content. Using the color gradients as a proxy for gradients in the M/L ratio, we measure half-mass radii for our sample of galaxies. There is significant scatter in individual r mass/r light ratios, which is correlated with variation in the color gradients. We find that the median r mass/r light ratio evolves from 0.75 at z = 2 to 0.5 at z = 1, consistent with previous results. We characterize the r mass - M * relation, and we find that it has a shallower slope and shows less redshift evolution than the r light - M * relation. This applies both to star-forming and quiescent galaxies. We discuss some of the implications of using r mass instead of r light, including an investigation of the size-inclination bias and a comparison to numerical simulations.

Keywords: Galaxy structure, High-redshift galaxies, Galaxy radii
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Density Structure of Centrally Concentrated Prestellar Cores from Multiscale Observations. Starless cores represent the initial stage of evolution toward (proto)star formation, and a subset of them, known as prestellar cores, with high density (~ 106 cm-3 or higher) and being centrally concentrated are expected to be embryos of (proto)stars. Determining the density profile of prestellar cores therefore provides an important opportunity to gauge the initial conditions of star formation. In this work, we perform rigorous modeling to estimate the density profiles of three nearly spherical prestellar cores among a sample of five highly dense cores detected by our recent observations. We employed multiscale observational data of the (sub)millimeter dust continuum emission, including those obtained by SCUBA-2 on the James Clerk Maxwell Telescope with a resolution of ~ 5600 au and by multiple Atacama Large Millimeter/submillimeter Array observations with a resolution as high as ~ 480 au. We are able to consistently reproduce the observed multiscale dust continuum images of the cores with a simple prescribed density profile, which bears an inner region of flat density and an r -2 profile toward the outer region. By utilizing the peak density and the size of the inner flat region as a proxy for the dynamical stage of the cores, we find that the three modeled cores are most likely unstable and prone to collapse. The sizes of the inner flat regions, as compact as ~ 500 au, signify them as being the highly evolved prestellar cores rarely found to date.

Keywords: Astronomy data modeling, Infrared dark clouds, Molecular clouds, Star formation, Astronomical methods, Collapsing clouds
Evidence for Black Holes in Green Peas from WISE Colors and Variability. We explore the presence of active galactic nuclei (AGNs)/black holes in Green Pea galaxies (GPs), motivated by the presence of high-ionization emission lines such as He II and [Ne III] in their optical spectra. In order to identify AGN candidates, we used mid-infrared (MIR) photometric observations from the all-sky Wide-field Infrared Survey Explorer (WISE) mission for a sample of 1004 GPs. Considering only &gt;5σ detections with no contamination from neighboring sources in AllWISE, we select 31 GPs out of 134 as candidate AGNs based on a stringent three-band WISE color diagnostic. Using multi-epoch photometry in W1 and W2 bands based on time-resolved unWISE coadd images, we find two sources exhibiting variability in both the WISE bands among 112 GPs with W1 ≤16 mag and no contamination from neighboring sources in unWISE. These two variable sources were selected as AGNs by the WISE three-band color diagnostic as well. Compared to variable AGN fractions observed among low-mass galaxy samples in previous studies, we find a higher fraction (~1.8%) of MIR variable sources among GPs, which demonstrates the uniqueness and importance of studying these extreme objects. Through this work, we demonstrate that MIR diagnostics are promising tools to select AGNs that may be missed by other selection techniques (including optical emission-line ratios and X-ray emission) in star formation-dominated, low-mass, low-metallicity galaxies.

Keywords: AGN host galaxies, Starburst galaxies, Black holes, Emission line galaxies, Galaxies
He Abundance of Dense Circumstellar Clumps in the Cassiopeia A Supernova Remnant. We report on the result of He abundance analysis of dense circumstellar clumps in the young supernova remnant Cassiopeia A. These clumps, which are called quasi-sta tionary flocculi (QSFs), are known from previous optical studies to be enriched in He along with N, but the degree of He overabundance relative to H has remained uncertain. For several QSFs with near-infrared spectroscopic data, we have analyzed their He I 1.083 μm/Paγ ratios together with the ratios of [Fe II] lines by using the Raymond shock code. According to our analysis, He is overabundant relative to H by a factor of ≲3 in most of these QSFs. This He abundance of QSFs is consistent with the previous conclusion from the N overabundance that QSFs were ejected when a substantial amount of the H envelope of the progenitor star had been stripped off. We discuss the mass-loss history of the progenitor star and the origin of QSFs.

Keywords: Supernova remnants, Type Ib supernovae, Circumstellar matter, Core-collapse supernovae
Symphony: Cosmological Zoom-in Simulation Suites over Four Decades of Host Halo Mass. We present Symphony, a compilation of 262 cosmological, cold-dark-matter-only zoom-in simulations spanning four decades of host halo mass, from 1011-1015 M ⊙. This compilation includes three existing simulation suites at the cluster and Milky Way-mass scales, and two new suites: 39 Large Magellanic Cloud-mass (1011 M ⊙) and 49 strong-lens-analog (1013 M ⊙) group-mass hosts. Across the entire host halo mass range, the highest-resolution regions in these simulations are resolved with a dark matter particle mass of ≈3 × 10-7 times the host virial mass and a Plummer-equivalent gravitational softening length of ≈9 × 10-4 times the host virial radius, on average. We measure correlations between subhalo abundance and host concentration, formation time, and maximum subhalo mass, all of which peak at the Milky Way host halo mass scale. Subhalo abundances are ≈50% higher in clusters than in lower-mass hosts at fixed sub-to-host halo mass ratios. Subhalo radial distributions are approximately self-similar as a function of host mass and are less concentrated than hosts' underlying dark matter distributions. We compare our results to the semianalytic model GALACTICUS, which predicts subhalo mass functions with a higher normalization at the low-mass end and radial distributions that are slightly more concentrated than Symphony. We use UNIVERSEMACHINE to model halo and subhalo star formation histories in Symphony, and we demonstrate that these predictions resolve the formation histories of the halos that host nearly all currently observable satellite galaxies in the universe. To promote open use of Symphony, data products are publicly available at http://web.stanford.edu/group/gfc/symphony.

Keywords: Galaxy dark matter halos, Computational methods, Galaxy abundances, N-body simulations, Dark matter
Multi-scale Physical Properties of NGC 6334 as Revealed by Local Relative Orientations between Magnetic Fields, Density Gradients, Velocity Gradients, and Gravity. We present ALMA dust polarization and molecular line observations toward four clumps (I(N), I, IV, and V) in the massive star-forming region NGC 6334. In conjunction with large-scale dust polarization and molecular line data from JCMT, Planck, and NANTEN2, we make a synergistic analysis of relative orientations between magnetic fields (θ B), column density gradients (θ NG), local gravity (θ LG), and velocity gradients (θ VG) to investigate the multi-scale (from ~30 to 0.003 pc) physical properties in NGC 6334. We find that the relative orientation between θ B and θ NG changes from statistically more perpendicular to parallel as column density ( ${N}_{{{\rm{H}}}_{2}}$ ) increases, which is a signature of trans-to-sub-Alfvénic turbulence at complex/cloud scales as revealed by previous numerical studies. Because θ NG and θ LG are preferentially aligned within the NGC 6334 cloud, we suggest that the more parallel alignment between θ B and θ NG at higher ${N}_{{{\rm{H}}}_{2}}$ is because the magnetic field line is dragged by gravity. At even higher ${N}_{{{\rm{H}}}_{2}}$ , the angle between θ B and θ NG or θ LG transits back to having no preferred orientation, or statistically slightly more perpendicular, suggesting that the magnetic field structure is impacted by star formation activities. A statistically more perpendicular alignment is found between θ B and θ VG throughout our studied ${N}_{{{\rm{H}}}_{2}}$ range, which indicates a trans-to-sub-Alfvénic state at small scales as well, and this signifies that magnetic field has an important role in the star formation process in NGC 6334. The normalized mass-to-flux ratio derived from the polarization-intensity gradient (KTH) method increases with ${N}_{{{\rm{H}}}_{2}}$ , but the KTH method may fail at high ${N}_{{{\rm{H}}}_{2}}$ due to the impact of star formation feedback.

Keywords: Molecular clouds, Magnetic fields, Star formation, Interstellar medium, Polarimetry
Terminator Habitability: The Case for Limited Water Availability on M-dwarf Planets. Rocky planets orbiting M-dwarf stars are among the most promising and abundant astronomical targets for detecting habitable climates. Planets in the M-dwarf habitable zone are likely synchronously rotating, such that we expect significant day-night temperature differences and potentially limited fractional habitability. Previous studies have focused on scenarios where fractional habitability is confined to the substellar or "eye" region, but in this paper we explore the possibility of planets with terminator habitability, defined by the existence of a habitable band at the transition between a scorching dayside and a glacial nightside. Using a global climate model, we show that for water-limited planets it is possible to have scorching temperatures in the "eye" and freezing temperatures on the nightside, while maintaining a temperate climate in the terminator region, due to reduced atmospheric energy transport. On water-rich planets, however, increasing the stellar flux leads to increased atmospheric energy transport and a reduction in day-night temperature differences, such that the terminator does not remain habitable once the dayside temperatures approach runaway or moist greenhouse limits. We also show that while water-abundant simulations may result in larger fractional habitability, they are vulnerable to water loss through cold trapping on the nightside surface or atmospheric water vapor escape, suggesting that even if planets were formed with abundant water, their climates could become water-limited and subject to terminator habitability.

Keywords: M dwarf stars, Ocean planets, Exoplanets, Atmospheric clouds, Planetary atmospheres, M stars, Planetary science, Planetary climates, Habitable zone, Habitable planets, Exoplanet atmospheres
Applying the Metallicity-dependent Binary Fraction to Double White Dwarf Formation: Implications for LISA. Short-period double white dwarf (DWD) binaries will be the most prolific source of gravitational waves (GWs) for the Laser Interferometer Space Antenna (LISA). DWDs with GW frequencies below ~1 mHz will be the dominant contributor to a stochastic foreground caused by overlapping GW signals. Population modeling of Galactic DWDs typically assumes a binary fraction of 50% and a log-uniform zero-age main sequence (ZAMS) orbital period distribution. However, recent observations have shown that the binary fraction of close, solar-type stars exhibits a strong anticorrelation with metallicity that modulates the ZAMS orbital period distribution below 104 days. In this study, we perform the first simulation of the Galactic DWD population observable by LISA that incorporates an empirically derived metallicity-dependent binary fraction, using the binary population synthesis suite COSMIC and a metallicity-dependent star formation history. We compare two models: one that assumes a metallicity-dependent binary fraction, and one with a binary fraction of 50%. We repeat our analysis for three different assumptions for Roche-lobe overflow interactions. We find that while metallicity impacts the evolution and intrinsic properties of our simulated DWD progenitor binaries, the LISA-resolvable populations of the two models remain roughly indistinguishable. However, the size of the total Galactic DWD population orbiting in the LISA frequency band is reduced by more than half when accounting for a metallicity-dependent binary fraction for two of our four variations, which also lowers the effective foreground. The LISA population remains unchanged in number for two variations, highlighting the sensitivity of the population to binary evolution prescriptions.

Keywords: Close binary stars, White dwarf stars, Gravitational wave sources, Stellar evolution