Sazuna/UAT_keywords huggingface dataset:
Lyα Radiative Transfer: Modeling Spectrum and Surface Brightness Profiles of Lyα-emitting Galaxies at Z = 3-6. We perform Lyα radiative transfer calculations to reproduce the Lyα properties of star-forming galaxies at high redshifts. We model a galaxy as a halo in which the density distributions of Lyα sources and H I plus dust medium are described with exponential functions. We also consider an outflow of the medium that represents a momentum-driven wind in a gravitational potential well. We successfully reproduce both the spectra and the surface brightness profiles of eight star-forming galaxies at z = 3-6 observed with the Multi-Unit Spectroscopic Explorer using this outflowing-halo model with Lyα scattering. The best-fit model parameters (i.e., the outflowing velocity and optical depth) for these galaxies are consistent with those in other studies. We examine the impacts of individual model parameters and input spectrum on the emerging spectrum and surface brightness profile. Further investigations of the correlations among observables (i.e., the spatial extent of Lyα halos and Lyα spectral features) and model parameters, and of spatially resolved spectra are presented as well. We demonstrate that the combination of spectrum and surface brightness profile provides strong constraints on model parameters and thus on the spatial/kinematic distributions of the medium.

Keywords: Lyman-alpha galaxies, Radiative transfer, Interstellar medium, Circumgalactic medium, Extragalactic astronomy, Radiative transfer simulations, Interstellar medium wind, High-redshift galaxies
Gas Content Regulates the Life Cycle of Star Formation and Black Hole Accretion in Galaxies. Feedback from active galactic nuclei (AGNs) is expected to impact the amount of cold gas in galaxies by driving strong galactic winds, by preventing external gas inflows, or by changing the thermodynamical state of the gas. We use estimates of molecular gas mass based on dust absorption (Hα/Hβ) to study gas content of large samples of type 2 AGN host galaxies in comparison with inactive galaxies. Using sparse principal component and clustering analysis, we analyze a suite of stellar and structural parameters of ∼27,100 face-on, central galaxies at redshift z = 0.02-0.15 and with stellar mass M⋆ ≈ 1010-2 × 1011 M⊙. We identify four galaxy groups of similar mass and morphology (mass surface density, velocity dispersion, concentration, and Sérsic index) that can be evolutionarily linked through a life cycle wherein gas content mediates their star formation rate (SFR) and level of AGN activity. Galaxies first consume their gas mostly through bursty star formation, then enter into a transition phase of intermediate gas richness in which star formation and AGNs coexist, before settling into retirement as gas-poor, quiescent systems with residual levels of AGN activity (LINERs). Strongly accreting black holes (Seyferts) live in gas-rich, star-forming hosts, but neither their gas reservoir nor their ability to form stars seems to be impacted instantaneously (timescales ≲0.5 Gyr) by AGN feedback. Our results are inconsistent with AGN feedback models that predict that central, bulge-dominated, Seyfert-like AGNs in massive galaxies have significantly lower molecular gas fractions than inactive galaxies of similar mass, morphology, and SFR.

Keywords: AGN host galaxies, Molecular gas, Supermassive black holes, Interstellar dust extinction, Seyfert galaxies, Active galactic nuclei, Galaxy evolution
HST Proper Motions of NGC 147 and NGC 185: Orbital Histories and Tests of a Dynamically Coherent Andromeda Satellite Plane. We present the first proper-motion (PM) measurements for the dwarf elliptical galaxies NGC 147 and NGC 185, two satellite galaxies of M31, using multiepoch Hubble Space Telescope (HST) imaging data with time baselines of ∼8 yr. For each galaxy, we take an error-weighted average of measurements from HST Advanced Camera for Surveys/WFC and Wide Field Camera 3/UVIS to determine the PMs. Our final results for the PMs are (μW, μN)N147 = (-0.0232, 0.0378) ± (0.0143, 0.0146) mas yr-1 for NGC 147 and (μW, μN)N185 = (-0.0242, 0.0058) ± (0.0141, 0.0147) mas yr-1 for NGC 185. The 2D direction of motion for NGC 147 about M31 is found to be aligned with its tidal tails. The 3D positions and velocities of both galaxies are transformed into a common M31-centric coordinate system to study the detailed orbital histories of the combined M31+NGC 147+NGC 185 system via numerical orbit integration. We find that NGC 147 (NGC 185) had its closest passage to M31 0.3-0.5 Gyr (≳1.6 Gyr) within the past 6 Gyr at distances of ∼70 kpc (70-260 kpc). The pericentric times of NGC 147/NGC 185 correlate qualitatively well with the presence/absence of tidal tails seen around the galaxies. Our PMs show that the orbital poles of NGC 147, as well as NGC 185, albeit to a lesser degree, agree within the uncertainties with the normal of the Great Plane of Andromeda (GPoA). These are the first measurements of the 3D angular momentum vector of any satellite identified as original GPoA members. Our results strengthen the hypothesis that the GPoA may be a dynamically coherent entity. We revisit previous claims that NGC 147 and NGC 185 are binary galaxies and conclude that it is very unlikely that the two galaxies were ever gravitationally bound to each other.

Keywords: Local Group, Galaxy dynamics, Dwarf elliptical galaxies, Proper motions, Andromeda Galaxy
The Art of Modeling Stellar Mergers and the Case of the B[e] Supergiant R4 in the Small Magellanic Cloud. Most massive stars exchange mass with a companion, leading to evolution which is altered drastically from that expected of stars in isolation. Such systems result from unusual binary evolution pathways and can place stringent constraints on the physics of these interactions. We use the R4 binary system's B[e] supergiant, which has been postulated to be the product of a stellar merger, to guide our understanding of such outcomes by comparing observations of R4 to the results of simulating a merger with the 3D hydrodynamics code FLASH. Our approach tailors the simulation initial conditions to observed properties of R4 and implements realistic stellar profiles from the 1D stellar evolution code MESA onto the 3D grid, resolving the merger inspiral to within 0.02 R⊙. We map the merger remnant into MESA to track its evolution on the H-R diagram over a period of 104 yr. This generates a model for a B[e] supergiant with stellar properties, age, and nebula structure in qualitative agreement with those of the R4 system. Our calculations provide evidence to support the idea that R4's B[e] supergiant was originally a member of a triple system in which the inner binary merged after its most massive member evolved off the main sequence, producing a new object of similar mass but significantly more luminosity than the A supergiant companion. The code framework presented in this paper, which was constructed to model tidal encounters, can be used to generate accurate models of a wide variety of merger stellar remnants.

Keywords: Hydrodynamical simulations, Binary stars, Stellar mergers
The Role of Successive and Interacting CMEs in the Acceleration and Release of Solar Energetic Particles: Multi-viewpoint Observations. Gradual and large solar energetic particle (SEP) events (flux of ions with energy &gt;10 MeV above 10 pfu) are primarily produced in shocks driven by fast and wide coronal mass ejections (CMEs). Past research, both in theory and statistics, has found that the situation where a fast primary CME (priCME) is preceded by previous CMEs (preCMEs) is favorable to a more efficient particle acceleration. However, the physical causes of this association is still a matter of debate, including the association of the acceleration and release of SEPs with the interaction of successive CMEs. Taking advantage of the twin Solar TErrestrial RElations Observatory spacecraft, we study 41 large SEP events in solar cycle 24 by multi-viewpoint observations. Although 21 events (∼51%) have a preCME identifiable in the Large Angle and Spectrometric Coronagraph, we determine that the priCMEs overlap the preCMEs in three dimension (3D) for only 11 events (∼27%). We further investigate the acceleration (using type II radio bursts) and release (using velocity dispersion analysis) of the particles for all potential instances of CME-CME interaction in 3D. We find that, for six of 11 events, the priCME is far away from catching up with the preCME when the particles are released. However, for the limited samples, the SEP peak intensity is significantly higher in the events in which the priCME is closest to impacting the preCME, indicating the potential for the increased seed population or more enhanced turbulence levels occurring closer to the preCME.

Keywords: Solar energetic particles, Solar coronal mass ejections
Atmospheric Dynamics on Terrestrial Planets with Eccentric Orbits. The insolation a planet receives from its parent star is the main driver of the climate and depends on the planet's orbital configuration. Planets with nonzero obliquity and eccentricity experience variations in seasonal insolation. As a result, the climate exhibits a seasonal cycle, with its strength depending on the orbital configuration and atmospheric characteristics. In this study, using an idealized general circulation model, we examine the climate response to changes in eccentricity for both zero and nonzero obliquity planets. In the zero obliquity case, a comparison between the seasonal response to changes in eccentricity and perpetual changes in the solar constant shows that the seasonal response strongly depends on the orbital period and radiative timescale. More specifically, using a simple energy balance model, we show the importance of the latitudinal structure of the radiative timescale in the climate response. We also show that the response strongly depends on the atmospheric moisture content. The combination of an eccentric orbit with nonzero obliquity is complex, as the insolation also depends on the perihelion position. Although the detailed response of the climate to variations in eccentricity, obliquity, and perihelion is involved, the circulation is constrained mainly by the thermal Rossby number and the maximum temperature latitude. Finally, we discuss the importance of different planetary parameters that affect the climate response to orbital configuration variations.

Keywords: Elliptical orbits, Planetary atmospheres, Exoplanet atmospheres, Atmospheric circulation
A Comparative Study of Mid-infrared Star Formation Rate Tracers and Their Metallicity Dependence. We present a comparative study of a set of star formation rate (SFR) tracers based on mid-infrared emission in the 12.81 μm [Ne II] line, the 15.56 μm [Ne III] line, and emission features from polycyclic aromatic hydrocarbons (PAHs) between 5.2 and 14.7 μm. We calibrate our tracers with the thermal component of the radio continuum emission at 33 GHz from 33 extranuclear star-forming regions observed in nearby galaxies. Correlations between mid-IR emission features and thermal 33 GHz SFRs show significant metallicity-dependent scatter and offsets. We find similar metallicity-dependent trends in commonly used SFR tracers such as Hα and 24 μm. As seen in previous studies, PAH emission alone is a poor SFR tracer owing to a strong metallicity dependence: lower-metallicity regions show decreased PAH emission relative to their SFR compared to higher-metallicity regions. We construct combinations of PAH bands, neon emission lines, and their respective ratios to minimize metallicity trends. The calibrations that most accurately trace SFR with minimal metallicity dependence involve the sum of the integrated intensities of the 12.81 μm [Ne II] line and the 15.56 μm [Ne III] line combined with any major PAH feature normalized by dust continuum emission. This mid-IR calibration is a useful tool for measuring SFR, as it is minimally sensitive to variations in metallicity and is composed of bright, ubiquitous emission features. The Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope will detect these features from galaxies as far as redshift z ∼ 1. We also investigate the behavior of the PAH band ratios and find that subtracting the local background surrounding a star-forming region decreases the ratio of PAH 11.3 μm to 7.7 μm emission. This implies that PAHs are more ionized in star-forming regions relative to their surroundings.

Keywords: Polycyclic aromatic hydrocarbons, Star forming regions, Star formation, Radio continuum emission, Metallicity
Evidence from the H3 Survey That the Stellar Halo Is Entirely Comprised of Substructure. In the ΛCDM paradigm, the Galactic stellar halo is predicted to harbor the accreted debris of smaller systems. To identify these systems, the H3 Spectroscopic Survey, combined with Gaia, is gathering 6D phase-space and chemical information in the distant Galaxy. Here we present a comprehensive inventory of structure within 50 kpc from the Galactic center using a sample of 5684 giants at $| b| \gt 40^\circ $ and $| Z| \gt 2\,\mathrm{kpc}$ . We identify known structures including the high-α disk, the in situ halo (disk stars heated to eccentric orbits), Sagittarius (Sgr), Gaia-Sausage-Enceladus (GSE), the Helmi Streams, Sequoia, and Thamnos. Additionally, we identify the following new structures: (i) Aleph ([Fe/H] = -0.5), a low-eccentricity structure that rises a surprising 10 kpc off the plane, (ii) and (iii) Arjuna ([Fe/H] = -1.2) and I'itoi ([Fe/H] &lt; -2), which comprise the high-energy retrograde halo along with Sequoia, and (iv) Wukong ([Fe/H] = -1.6), a prograde phase-space overdensity chemically distinct from GSE. For each structure, we provide [Fe/H], [α/Fe], and orbital parameters. Stars born within the Galaxy are a major component at $| Z| \sim 2\,\mathrm{kpc}$ (≈60%), but their relative fraction declines sharply to ≲5% past 15 kpc. Beyond 15 kpc, &gt;80% of the halo is built by two massive (M⋆ ∼ 108-109M⊙) accreted dwarfs: GSE ([Fe/H] = -1.2) within 25 kpc and Sgr ([Fe/H] = -1.0) beyond 25 kpc. This explains the relatively high overall metallicity of the halo ([Fe/H] ≈ -1.2). We attribute ≳95% of the sample to one of the listed structures, pointing to a halo built entirely from accreted dwarfs and heating of the disk.

Keywords: Galaxy formation, Milky Way formation, Galaxy stellar halos, Milky Way stellar halo, Galaxy kinematics, Galaxy evolution, Milky Way evolution, Milky Way Galaxy
Modeling Unresolved Binaries of Open Clusters in the Color-Magnitude Diagram. I. Method and Application of NGC 3532. The binary properties of open clusters place crucial constraints on star formation theory and clusters' dynamical evolution. We develop a comprehensive approach that models the color-magnitude diagram (CMD) of the cluster members as a mixture of single stars and photometric unresolved binaries. This method enables us to infer the binary properties, including the binary fraction fb and binary mass ratio distribution index γq when a power law is assumed, with high accuracy and precision, which was unfeasible in conventional methods. We employ a modified Gaussian process to determine the main-sequence ridgeline and its scatter from the observed CMD as model input. As a first example, we apply the method to the open cluster NGC 3532 with the Gaia DR2 photometry. For the cluster members within a magnitude range corresponding to FGK dwarfs, we obtain fb = 0.267 ± 0.019 and γq = -0.10 ± 0.22 for binaries with mass ratio q &gt; 0.2. The fb value is consistent with the previous work on NGC 3532 and smaller than that of field stars. The close-to-zero γq indicates that the mass ratios of binaries follow a nearly uniform distribution. For the first time, we unveil that the stars with smaller mass or in the inner region tend to have lower fb and a more positive value of γq due to the lack of low mass ratio binaries. The clear dependences of binary properties on mass and radius are most likely caused by the internal dynamics. In this scheme, binaries with smaller primary mass or lower mass ratio have smaller binding energy; hence, they are more vulnerable to dynamical disruption, especially in the inner region where stars interact more frequently.

Keywords: Mixture model, Open star clusters, Binary stars
Star-forming versus Quiescent Regions in the Galaxy: A Case Study of ISM Properties Based on 18 cm OH and <SUP>12</SUP>CO (1-0) Observations. We infer the density of hydrogen nuclei and optical depths associated with molecular gas in front of a star-forming region and in a quiescent region of the Galactic interstellar medium (ISM) using 18 cm OH and archival 3 mm 12CO observations, together with a diffuse cloud model from the literature. The results indicate that the volume densities of hydrogen nuclei are greatest near the star-forming region, intermediate in the CO-bright portions of the quiescent region, and lowest in the CO-dark portions of the quiescent region. Low volume density and low column density appear to be correlated with the presence of CO-dark molecular gas, which is primarily located in the vast space outside of star-forming regions. Molecular gas containing CO may exist in similar quantities both outside of and in the vicinity of star-forming regions; however, the CO emission radiates more efficiently in regions where the ISM is locally compressed, leading to the observational phenomenon of CO-dark and CO-bright molecular gas. We suggest that processes occurring as a natural consequence of star formation such as shock waves and stellar winds lead to compression of the gas into smaller pockets of higher volume density, and such "clumpy" structures will naturally emit more efficiently in CO owing to higher rates of collisional excitation. In this picture, the apparent prominence of CO emission in and near star-forming regions is itself a by-product of the star formation process.

Keywords: Radio spectroscopy, Molecular gas, Surveys, Galaxy structure, Molecular clouds, Interstellar medium
Unusual Galactic H II Regions at the Intersection of the Central Molecular Zone and the Far Dust Lane. Sgr E is a massive star formation complex found toward the Galactic center that consists of numerous discrete, compact H II regions. It is located at the intersection between the central molecular zone (CMZ) and the far dust lane of the Galactic bar, similar to "hot spots" seen in external galaxies. Compared with other Galactic star formation complexes, the Sgr E complex is unusual because its H II regions all have similar radio luminosities and angular extents, and they are deficient in ∼10 μm emission from their photodissociation regions (PDRs). Our Green Bank Telescope radio recombination line observations increase the known membership of Sgr E to 19 H II regions. There are 43 additional H II region candidates in the direction of Sgr E, 26 of which are detected for the first time here using MeerKAT 1.28 $\,\mathrm{GHz}$ data. Therefore, the true H II region population of Sgr E may number &gt;60. Using APEX SEDIGISM 13CO $2\to 1$ data we discover a 3.0 × 105 $\,{M}_{\odot }$ molecular cloud associated with Sgr E, but find few molecular or far-infrared concentrations at the locations of the Sgr E H II regions. Comparison with simulations and an analysis of its radio continuum properties indicate that Sgr E formed upstream in the far dust lane of the Galactic bar a few million years ago and will overshoot the CMZ, crashing into the near dust lane. We propose that the unusual infrared properties of the Sgr E H II regions are caused by their orbits about the Galactic center, which have possibly stripped their PDRs.

Keywords: Radio continuum emission, Galactic center, H II regions, Interstellar medium
A Modified Algorithm and Open-source Computational Package for the Determination of Infrared Optical Constants Relevant to Astrophysics. Infrared (IR) telescopes, such as Spitzer and SOFIA, have revealed a rich variety of chemical species trapped in interstellar ices. The most fundamental parameters to be derived from observed IR spectra are the identity and abundance of each component. Several compounds have been conclusively or tentatively identified, but the band strengths and optical constants needed to derive accurate abundances for many of these are poorly constrained. We have developed a modified approach to the extraction of the real and imaginary parts of the refractive index (optical constants) of a thin film from a single transmission spectrum measured in the IR spectral range. Our algorithm is similar to those implemented by previous authors, with some major changes that yield results for strong absorptions where previous approaches fail: (1) an adaptive k-correction step size, (2) the use of a root-finding algorithm to obtain a more accurate k-correction at each iteration, and (3) a k-correction step that prevents non-physical results such as negative n-values that prevent convergence in the calculation algorithm. The algorithm is presented and described, with examples to show agreement with some existing results and improvements upon others. New optical-constants calculations for CH3OH, CO2, N2O, and CH4 are presented, and potential implications for the modeling of interstellar and planetary ice data from space telescopes are discussed. With the objective of being open-source and transparent, the full source code in the free Python programming language is made available along with the compiled version and the laboratory data used to produce the results shown.

Keywords: Molecular spectroscopy, Laboratory astrophysics, Astrochemistry
Simulating Jets from a Neutron Star Companion Hours after a Core-collapse Supernova. We conduct three-dimensional hydrodynamical simulations to explore the interaction of the jets that a neutron star (NS) companion to a type Ic or type Ib core-collapse supernova (CCSN) launches a few hours after explosion with the ejecta of the CCSN. We assume that an NS companion at 5 R⊙ from the exploding star accretes mass from the slower inner ejecta through an accretion disk, and that the disk launches two opposite jets. Although the energy of the jets is only about one percent of the total energy of the ejecta, it is comparable to the energy of the slower inner part of the ejecta. We find that the jets inflate one low-density hot bubble to one side of the ejecta, and that this bubble expands to influence ejecta gas up to expansion velocities of ${v}_{\mathrm{ej}}\simeq 3500\,\mathrm{km}\,{{\rm{s}}}^{-1}$ . The postshock jets' material develops a large meridional flow and small vortexes. The boundary between the ejecta and jets' postshock gases is unstable. The instabilities and vortexes mix jets' gas with the ejecta. We expect such a hot bubble to contribute to the light curve of CCSNe that are progenitors of binary NS systems, in particular to observers on the side of the bubble.

Keywords: Neutron stars, Type Ic supernovae, Jets, High energy astrophysics, Type Ib supernovae, Massive stars, Compact binary stars, Interacting binary stars, Supernova dynamics