Sazuna/UAT_keywords huggingface dataset:
Science-driven Tunable Design of Cosmic Explorer Detectors. Ground-based gravitational-wave detectors like Cosmic Explorer (CE) can be tuned to improve their sensitivity at high or low frequencies by tuning the response of the signal extraction cavity. Enhanced sensitivity above 2 kHz enables measurements of the post-merger gravitational-wave spectrum from binary neutron star mergers, which depends critically on the unknown equation of state of hot, ultra-dense matter. Improved sensitivity below 500 Hz favors precision tests of extreme gravity with black hole ringdown signals and improves the detection prospects while facilitating an improved measurement of source properties for compact binary inspirals at cosmological distances. At intermediate frequencies, a more sensitive detector can better measure the tidal properties of neutron stars. We present and characterize the performance of tuned CE configurations that are designed to optimize detections across different astrophysical source populations. These tuning options give CE the flexibility to target a diverse set of science goals with the same detector infrastructure. We find that a 40 km CE detector outperforms a 20 km in all key science goals other than access to post-merger physics. This suggests that CE should include at least one 40 km facility.

Keywords: Gravitational wave detectors, Gravitational wave astronomy, General relativity, Gravitational waves, Particle astrophysics
Residual Abundances in GALAH DR3: Implications for Nucleosynthesis and Identification of Unique Stellar Populations. We investigate the [X/Mg] abundances of 16 elements for 82,910 Galactic disk stars from GALAH+ DR3. We fit the median trends of low-Ia and high-Ia populations with a two-process model, which describes stellar abundances in terms of a prompt core-collapse and delayed Type-Ia supernova component. For each sample star, we fit the amplitudes of these two components and compute the residual Δ[X/H] abundances from this two-parameter fit. We find rms residuals ≲0.07 dex for well-measured elements and correlated residuals among some elements (such as Ba, Y, and Zn) that indicate common enrichment sources. From a detailed investigation of stars with large residuals, we infer that roughly 40% of the large deviations are physical and 60% are caused by problematic data such as unflagged binarity, poor wavelength solutions, and poor telluric subtraction. As one example of a population with distinctive abundance patterns, we identify 15 stars that have 0.3-0.6 dex enhancements of Na but normal abundances of other elements from O to Ni and positive average residuals of Cu, Zn, Y, and Ba. We measure the median elemental residuals of 14 open clusters, finding systematic ~0.1-0.4 dex enhancements of O, Ca, K, Y, and Ba and ~0.2 dex depletion of Cu in young clusters. Finally, we present a restricted three-process model where we add an asymptotic giant branch star (AGB) component to better fit Ba and Y. With the addition of the third process, we identify a population of stars, preferentially young, that have much higher AGB enrichment than expected from their SNIa enrichment.

Keywords: Core-collapse supernovae, Chemical abundances, Asymptotic giant branch stars, Type Ia supernovae, Galactic abundances
Photodissociation Rate, Excess Energy, and Kinetic Total Energy Release for the Photolysis of H<SUB>2</SUB>O Producing O(<SUP>1</SUP>S) by Solar UV Radiation Field. Forbidden atomic oxygen lines in emission are ubiquitous for cometary spectra in the visible region, and the oxygen atoms in metastable states causing the forbidden emission lines are considered as a proxy of H2O in coma. However, the photodissociation rate and related quantities for the dissociation reaction producing O(1S) from H2O have never been estimated based on experimental studies. Based on the recent laboratory study of the photodissociation reaction of H2O producing O(1S) by Chang et al., we derived the photodissociation rates of the reactions for both the O(1S) and O(1D) channels, consistent with the green-to-red line ratios observed in comets so far. Furthermore, the total kinetic energies released for the photodissociation products are also consistent with the intrinsic line widths of forbidden atomic oxygen emission lines observed in comets. The photodissociation rates of H2O leading to O(1S) and O(1D) calculated here do not significantly change the previous estimates of CO2/H2O in comets based on the green-to-red line ratios of the comets if we use the photodissociation rates of CO2 (calculated elsewhere) with a correction for the difference of solar UV spectra used for calculating photodissociation rates of H2O and CO2.

Keywords: Molecular physics
Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images. For testing different electron temperature (T e) prescriptions in general relativistic magnetohydrodynamics (GRMHD) simulations through observations, we propose to utilize linear polarization (LP) and circular polarization (CP) images. We calculate the polarization images based on a semi-magnetically arrested disk GRMHD model for various T e parameters, bearing M87 in mind. We find an LP-CP separation in the images of the low-T e disk cases at 230GHz; namely, the LP flux mainly originates from downstream of the jet, and the CP flux comes from the counter-side jet, while the total intensity is maximum at the jet base. This can be understood as follows: although the LP flux is generated through synchrotron emission widely around the black hole, most of the LP flux from the jet base does not reach the observer, since it undergoes Faraday rotation ( $\propto {T}_{{\rm{e}}}^{-2}$ ) when passing through the outer cold disk and is thus depolarized. Hence, only the LP flux from the downstream (not passing the cold dense plasmas) can survive. Meanwhile, the CP flux is generated from the LP flux by Faraday conversion ( ∝ T e) in the inner hot region. Stronger CP flux is thus observed from the counter-side jet. Moreover, the LP-CP separation is more enhanced at a lower frequency, such as 86 GHz, but is rather weak at 43 GHz, since the media in the latter case is optically thick for synchrotron self-absorption so that all of the fluxes should come from the photosphere. The same is true for cases with higher mass accretion rates and/or larger inclination angles.

Keywords: Black hole physics, Radio jets, Active galactic nuclei, Radiative transfer, Polarimetry
Using Statistical Emulation and Knowledge of Grain-surface Diffusion for Bayesian Inference of Reaction Rate Parameters: An Application to a Glycine Network. There exists much uncertainty surrounding interstellar grain-surface chemistry. One of the major reaction mechanisms is grain-surface diffusion for which the binding energy parameter for each species needs to be known. However, these values vary significantly across the literature which can lead to debate as to whether or not a particular reaction takes place via diffusion. In this work we employ Bayesian inference to use available ice abundances to estimate the reaction rates of the reactions in a chemical network that produces glycine. Using this we estimate the binding energy of a variety of important species in the network, by assuming that the reactions take place via diffusion. We use our understanding of the diffusion mechanism to reduce the dimensionality of the inference problem from 49 to 14, by demonstrating that reactions can be separated into classes. This dimensionality reduction makes the problem computationally feasible. A neural network statistical emulator is used to also help accelerate the Bayesian inference process substantially. The binding energies of most of the diffusive species of interest are found to match some of the disparate literature values, with the exceptions of atomic and diatomic hydrogen. The discrepancies between these two species are related to the limitations of the physical and chemical models. However, the use of a dummy reaction of the form H + X $\longrightarrow $ HX is found to somewhat reduce the discrepancy with the binding energy of atomic hydrogen. Using the inferred binding energies in the full gas-grain version of UCLCHEM results in almost all the molecular abundances being recovered.

Keywords: Bayesian statistics, Interstellar abundances, Reaction rates, Astrochemistry, Dark interstellar clouds, Astrostatistics strategies
Early-stage Coronal Hard X-Ray Source in Solar Flares in the Collapsing Trap Model. A bright hard X-ray coronal source observed at the early stage of solar flares is considered. The plasma density in a quiet corona is not enough to explain the hard X-ray bremsstrahlung radiation. The generally accepted concept of increasing plasma density in the looptop is associated with the effect of evaporation of hot chromosphere plasma. We discuss the increase in plasma density at the looptop at the early stage of a flare, due to magnetic loop contraction during the relaxation of the magnetic field (the so-called collapsing trap model). In this case, the increase in the plasma density at the looptop occurs on a timescale of seconds-tens of seconds, while the process of plasma evaporation increases the plasma density for much longer. The Fokker-Planck kinetic equation for accelerated electrons with a betatron and Fermi terms is solved numerically. We calculate increases in the energy of the accelerated electrons, the energy spectrum, and the pitch-angle anisotropy due to betatron and Fermi first-order acceleration. For a collapse time of 8 s, the total energy of the accelerated electrons increases by ~20%-200%, depending on the model parameters. The ratio of the looptop/total hard X-ray flux at 29-58 keV increases by 15%-30% in the collapsing trap model. It is shown that this model can explain the appearance of bright coronal hard X-ray sources in the first seconds-tens of seconds after the hard X-ray flux starts growing.

Keywords: Solar activity, Active solar corona, Solar active regions, Solar flares
Dependence of X <SUB>CO</SUB> on Metallicity, Intensity, and Spatial Scale in a Self-regulated Interstellar Medium. We study the CO(1-0)-to-H2 conversion factor (X CO) and the line ratio of CO(2-1)-to-CO(1-0) (R 21) across a wide range of metallicity (0.1 ≤ Z/Z ⊙ ≤ 3) in high-resolution (~0.2 pc) hydrodynamical simulations of a self-regulated multiphase interstellar medium. We construct synthetic CO emission maps via radiative transfer and systematically vary the observational beam size to quantify the scale dependence. We find that the kpc-scale X CO can be overestimated at low Z if assuming steady-state chemistry or assuming that the star-forming gas is H2 dominated. On parsec scales, X CO varies by orders of magnitude from place to place, primarily driven by the transition from atomic carbon to CO. The parsec-scale X CO drops to the Milky Way value of $2\times {10}^{20}\ {\mathrm{cm}}^{-2}\,{\left({\rm{K}}\,\mathrm{km}\,{{\rm{s}}}^{-1}\right)}^{-1}$ once dust shielding becomes effective, independent of Z. The CO lines become increasingly optically thin at lower Z, leading to a higher R 21. Most cloud area is filled by diffuse gas with high X CO and low R 21, while most CO emission originates from dense gas with low X CO and high R 21. Adopting a constant X CO strongly over- (under-)estimates H2 in dense (diffuse) gas. The line intensity negatively (positively) correlates with X CO (R 21) as it is a proxy of column density (volume density). On large scales, X CO and R 21 are dictated by beam averaging, and they are naturally biased toward values in dense gas. Our predicted X CO is a multivariate function of Z, line intensity, and beam size, which can be used to more accurately infer the H2 mass.

Keywords: Hydrodynamical simulations, Interstellar medium, Astrochemistry
Measuring the Density Fields around Bright Quasars at z   6 with XQR-30 Spectra. Measuring the density of the intergalactic medium using quasar sight lines in the epoch of reionization is challenging due to the saturation of Lyα absorption. Near a luminous quasar, however, the enhanced radiation creates a proximity zone observable in the quasar spectra where the Lyα absorption is not saturated. In this study, we use 10 high-resolution (R ≳ 10,000) z ~ 6 quasar spectra from the extended XQR-30 sample to measure the density field in the quasar proximity zones. We find a variety of environments within 3 pMpc distance from the quasars. We compare the observed density cumulative distribution function (CDF) with models from the Cosmic Reionization on Computers simulation and find a good agreement between 1.5 and 3 pMpc from the quasar. This region is far away from the quasar hosts and hence approaching the mean density of the universe, which allows us to use the CDF to set constraints on the cosmological parameter σ 8 = 0.6 ± 0.3. The uncertainty is mainly due to the limited number of high-quality quasar sight lines currently available. Utilizing the more than 200 known quasars at z ≳ 6, this method will allow us to tighten the constraint on σ 8 to the percent level in the future. In the region closer to the quasar within 1.5 pMpc, we find that the density is higher than predicted in the simulation by 1.23 ± 0.17, suggesting that the typical host dark matter halo mass of a bright quasar (M 1450 &lt; -26.5) at z ~ 6 is ${\mathrm{log}}_{10}({M}_{h}/{M}_{\odot })={12.5}_{-0.7}^{+0.4}$ .

Keywords: Cosmology, AGN host galaxies, Large-scale structure of the universe, Quasars, Interstellar medium, Reionization
The Impact and Mechanism of the Magnetic Inclination Angle on O<SUP>+</SUP> Escape from Mars. Ion escape from the atmosphere to space is one of the most likely reasons to account for the evolution of the Martian climate. Based on three-dimensional multifluid magnetohydrodynamic simulations, we investigated the impact of the magnetic inclination angle on O+ escape at low altitudes of 275-1000 km under the typical solar wind conditions. Numerical results showed that an outward ion velocity in the direction opposite to the electromagnetic (EM) force results in weak outward flux and leads to ions becoming trapped by the horizontal magnetic field lines at the local horizontal magnetic equator. Much of the EM force can be attributed to the Hall electric force. In the region of high absolute magnetic inclination angle, the outward ion velocity has the same direction as the EM force, which increases the outward flux and causes ions to diffuse upward along open magnetic field lines to higher altitude. In addition, the EM force is mainly provided by the electron pressure gradient force and the motional electric force. Global results for the magnetic inclination angle indicate that the strong crustal field regions in the southern hemisphere are mainly occupied by magnetic field lines with high absolute magnetic inclination angle, while horizontal field lines are dominant in the northern hemisphere, which leads to a higher O+ escape rate in the Martian southern hemisphere than in the northern, from altitudes of 275 to 1000 km. This is a significant advance in understanding the impact and mechanism of the Martian magnetic field directions on ion escape.

Keywords: Magnetic anomalies, Mars, Solar-planetary interactions, Magnetohydrodynamics
Coevolution of Brightest Cluster Galaxies and Their Host Clusters in IllustrisTNG. We use IllustrisTNG simulations to explore the dynamic scaling relation between massive clusters and their-central-brightest cluster galaxies (BCGs). The IllustrisTNG-300 simulation we use includes 280 massive clusters from the z = 0 snapshot with M 200 &gt; 1014 M ⊙, enabling a robust statistical analysis. We derive the line-of-sight velocity dispersion of the stellar particles of the BCGs (σ *,BCG), analogous to the observed BCG stellar velocity dispersion. We also compute the subhalo velocity dispersion to measure the cluster velocity dispersion (σ cl). Both σ *,BCG and σ cl are proportional to the cluster halo mass, but the slopes differ slightly. Thus, like the observed relation, σ *,BCG/σ cl declines as a function of σ cl, but the scatter is large. We explore the redshift evolution of the σ *,BCG - σ cl scaling relation for z ≲ 1 in a way that can be compared directly with observations. The scaling relation has a similar slope at high redshift, but the scatter increases because of the large scatter in σ *,BCG. The simulations imply that high-redshift BCGs are dynamically more complex than their low-redshift counterparts.

Keywords: Galaxy clusters, Brightest cluster galaxies, Magnetohydrodynamical simulations
Optical Observations and Modeling of the Superluminous Supernova 2018lfe. We present optical imaging and spectroscopy of SN 2018lfe, which we classify as a Type I superluminous supernova (SLSN-I) at a redshift of z = 0.3501 ± 0.0004 with a peak absolute magnitude of M  r  = -22.1 ± 0.1 mag, one of the brightest SLSNe discovered. SN 2018lfe was identified for follow-up using our FLEET machine-learning pipeline. Both the light curve and the spectra of SN 2018lfe are consistent with the broad population of SLSNe. We fit the light curve with a magnetar central engine model and find an ejecta mass of M ej ≍ 3.8 M ☉, a magnetar spin period of P ≍ 2.9 ms, and a magnetic field strength of B ⊥ ≍ 2.8 × 1014 G. The magnetic field strength is near the top of the distribution for SLSNe, while the spin period and ejecta mass are near the median values of the distribution for SLSNe. From late-time imaging and spectroscopy we find that the host galaxy of SN 2018lfe has an absolute magnitude of M  r  = -17.85 ± 0.24, (L  B  = 0.029 ± 0.007L*), and an inferred metallicity of Z ≍ 0.3 Z ☉ and star formation rate of ≍0.8 M ☉ yr-1.

Keywords: Supernovae, Core-collapse supernovae
Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2. In this study, 36 cores (30 starless and six protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio telescope, and mapped the cores in the J = 1 → 0 transitions of HCO+, H13CO+, N2H+, HNC, and HN13C. The asymmetry parameter δV, which was the ratio of the difference between the HCO+ and H13CO+ peak velocities to the H13CO+ line width, was biased toward negative values, suggesting that inward motions were more dominant than outward motions. Three starless cores (10% of all starless cores surveyed) were identified as cores with blue-skewed line profiles (asymmetric profiles with more intense blueshifted emission), and another two starless cores (7%) were identified as candidate blue-skewed line profiles. The peak velocity difference between HCO+ and H13CO+ of them was up to 0.9 km s-1, suggesting that some inward motions exceeded the speed of sound for the quiescent gas (~10-17 K). The mean of δV of the five aforementioned starless cores was derived to be -0.5 ± 0.3. One core, G211.16-19.33North3, observed using the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array in DCO+ J = 3 → 2 exhibited blue-skewed features. Velocity offset in the blue-skewed line profile with a dip in the DCO+ J = 3 → 2 line was larger (~0.5 km s-1) than that in HCO+ J = 1 → 0 (~0.2 km s-1), which may represent gravitational acceleration of inward motions. It seems that this core is at the last stage in the starless phase, judging from the chemical evolution factor version 2.0 (CEF2.0).

Keywords: Interstellar line emission, Star forming regions, Star formation, Interstellar clouds, Interstellar medium, Collapsing clouds
A Simulation-driven Deep Learning Approach for Separating Mergers and Star-forming Galaxies: The Formation Histories of Clumpy Galaxies in All of the CANDELS Fields. Being able to distinguish between galaxies that have recently undergone major-merger events, or are experiencing intense star formation, is crucial for making progress in our understanding of the formation and evolution of galaxies. As such, we have developed a machine-learning framework based on a convolutional neural network to separate star-forming galaxies from post-mergers using a data set of 160,000 simulated images from IllustrisTNG100 that resemble observed deep imaging of galaxies with Hubble. We improve upon previous methods of machine learning with imaging by developing a new approach to deal with the complexities of contamination from neighboring sources in crowded fields and define a quality control limit based on overlapping sources and background flux. Our pipeline successfully separates post-mergers from star-forming galaxies in IllustrisTNG 80% of the time, which is an improvement by at least 25% in comparison to a classification using the asymmetry (A) of the galaxy. Compared with measured Sérsic profiles, we show that star-forming galaxies in the CANDELS fields are predominantly disk-dominated systems while post-mergers show distributions of transitioning disks to bulge-dominated galaxies. With these new measurements, we trace the rate of post-mergers among asymmetric galaxies in the universe, finding an increase from 20% at z = 0.5 to 50% at z = 2. Additionally, we do not find strong evidence that the scattering above the star-forming main sequence can be attributed to major post-mergers. Finally, we use our new approach to update our previous measurements of galaxy merger rates ${ \mathcal R }=0.022\pm 0.006\times {(1+z)}^{2.71\pm 0.31}$ .

Keywords: Convolutional neural networks, Galaxy mergers
Spectroscopic Line Modeling of the Fastest Rotating O-type Stars. We present a spectroscopic analysis of the most rapidly rotating stars currently known, VFTS 102 ( ${v}_{e}\sin i=649\pm 52$ km s-1; O9: Vnnne+) and VFTS 285 ( ${v}_{e}\sin i=610\pm 41$ km s-1; O7.5: Vnnn), both members of the 30 Dor complex in the Large Magellanic Cloud. This study is based on high-resolution ultraviolet spectra from Hubble Space Telescope/Cosmic Origins Spectrograph and optical spectra from the Very Large Telescope (VLT) X-shooter plus archival VLT GIRAFFE spectra. We utilize numerical simulations of their photospheres, rotationally distorted shape, and gravity darkening to calculate model spectral line profiles and predicted monochromatic absolute fluxes. We use a guided grid search to investigate parameters that yield best fits for the observed features and fluxes. These fits produce estimates of the physical parameters for these stars (plus a Galactic counterpart, ζ Oph) including the equatorial rotational velocity, inclination, radius, mass, gravity, temperature, and reddening. We find that both stars appear to be radial-velocity constant. VFTS 102 is rotating at critical velocity, has a modest He enrichment, and appears to share the motion of the nearby OB-association LH 99. These properties suggest that the star was spun up through a close binary merger. VFTS 285 is rotating at 95% of critical velocity, has a strong He enrichment, and is moving away from the R136 cluster at the center of 30 Dor. It is mostly likely a runaway star ejected by a supernova explosion that released the components of the natal binary system.

Keywords: Massive stars, Stellar rotation, Large Magellanic Cloud