Sazuna/UAT_keywords huggingface dataset:
Infrared Spectral Energy Distributions and Dust Masses of Sub-solar Metallicity Galaxies at z   2.3. We present results from Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm continuum observations of a sample of 27 star-forming galaxies at z = 2.1-2.5 from the MOSFIRE Deep Evolution Field survey with metallicity and star formation rate measurements from optical emission lines. Using stacks of Spitzer, Herschel, and ALMA photometry (rest frame ~8-400 μm), we examine the infrared (IR) spectral energy distributions (SED) of z ~ 2.3 subsolar-metallicity (~0.5 Z ⊙) luminous infrared galaxies (LIRGs). We find that the data agree well with an average template of higher-luminosity local low-metallicity dwarf galaxies (reduced χ 2 = 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ultraluminous IR galaxies, even in the most favorable case (with reduced χ 2 = 2.8), the templates are rejected at &gt;98% confidence. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar-metallicity galaxies may result from different grain properties or a harder/more intense ionizing radiation field that increases the dust temperature. The obscured star formation rate (SFR) indicated by the far-IR emission of the subsolar-metallicity galaxies is only ~60% of the total SFR, considerably lower than that of the local LIRGs with ~96%-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data overestimate the Rayleigh-Jeans tail measurements by a factor of 2-20. These templates underestimate IR luminosities if fit to the observed ALMA fluxes by &gt;0.4 dex. At a given stellar mass or metallicity, dust masses at z ~ 2.3 are an order of magnitude higher than z ~ 0. Given the predicted molecular gas fractions, the observed z ~ 2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies with similar metallicities.

Keywords: Gas-to-dust ratio, Astronomical models, Galaxy chemical evolution, Dwarf galaxies, Galactic and extragalactic astronomy, Astrophysical dust processes, Chemical enrichment, Dust continuum emission, Galaxy evolution, Metallicity, High-redshift galaxies, Galaxies
Hydroaluminum Isocyanide Isomers: Prediction of Spectroscopic Properties. Metal cyanides and isocyanides play a relevant role in the metal chemistry of the carbon-rich circumstellar envelope IRC+10216. It is thought that hydrometal cyanides/isocyanides could also be present in these environments; in fact, HMgNC has been detected in the same source that MgCN, MgNC, and AlNC. The aim of this work is to provide information about hydroaluminum cyanide/isocyanide. For this goal, a comprehensive analysis of the doublet and quartet potential energy surfaces of the [Al, C, H, N] system has been carried out. Different quantum chemistry methodologies from density functional theory to ab initio have been employed. For the [Al, C, H, N] isomers, the stability against dissociation and their interconversion processes have been analyzed. Our results show that the most relevant isomers from an experimental point of view are HAlCN and HAlNC. HAlNC has been found to be the most stable isomer followed by HAlCN, which is located at 1.59 kcal mol-1 (0.0689 eV) at the composite level. The interconversion process between HAlCN and HAlNC presents an energy barrier of 10.0 kcal mol-1 (5032 K) that makes this process not viable in the interstellar medium. We provide a complete set of relevant spectroscopic parameters for rotational spectroscopy for both HAlCN and HAlNC isomers using state-of-the-art quantum chemical computations, mandatory to guide an eventual laboratory or interstellar detection. Moreover, both isomers present sizable μ  a  dipole moment components (3.7 and 3.3 D, respectively), which are large enough to enable a characterization by means of rotational spectroscopy, further increasing their interest as interstellar candidates.

Keywords: Interstellar molecules, Molecular spectroscopy, Astrochemistry
Pearls on a String: Numerous Stellar Clusters Strung Along the Same Orbit. Stars originate from the dense interstellar medium, which exhibits filamentary structure to scales of ~1 kpc in galaxies like our Milky Way. We explore quantitatively how much resulting large-scale correlation there is among different stellar clusters and associations in orbit-phase space, characterized here by actions and angles. As a starting point, we identified 55 prominent stellar overdensities in the 6D space of orbit (actions) and orbit-phase (angles) among the ~2.8 million stars with radial velocities from Gaia EDR3 and with d ≤ 800 pc. We then explored the orbit-phase distribution of all sample stars in the same orbit patch as any one of these 55 overdensities. We find that very commonly numerous other distinct orbit-phase overdensities exist along these same orbits, like pearls on a string. These "pearls" range from known stellar clusters to loose, unrecognized associations. Among orbit patches defined by one initial orbit-phase overdensity, 50% contain at least 8 additional orbit-phase pearls of 10 cataloged members; 20% of them contain 20 additional pearls. This is in contrast to matching orbit patches sampled from a smooth mock catalog, or offset nearby orbit patches, where there are only 2 (or 5, respectively) comparable pearls. Our findings quantify for the first time how common it is for star clusters and associations to form at distinct orbit-phases of nearly the same orbit. This may eventually offer a new way to probe the 6D orbit structure of the filamentary interstellar medium.

Keywords: Stellar kinematics, Milky Way dynamics, Milky Way disk, Stellar associations, Star clusters
Using Multiple Emission Line Ratios to Constrain the Slope of the Dust Attenuation Law. We explore the possibility and practical limitations of using a three-line approach to measure both the slope and normalization of the dust attenuation law in individual galaxies. To do this, we focus on a sample of 11 galaxies with existing ground-based Balmer Hα and Hβ measurements from slit spectra, plus space-based grism constraints on Paschen-β. When accounting for observational uncertainties, we show that one galaxy has a well-constrained dust-law slope and normalization in the range expected from theoretical arguments; this galaxy therefore provides an example of what may be possible in the future. However, most of the galaxies are best fit by unusually steep or shallow slopes. We then explore whether additional astrophysical effects or observational biases could explain the elevated Paschen-β/Hα ratios driving these results. We find that galaxies with high Paschen-β/Hα ratios may be explained by slightly sub-unity covering fractions (&gt;97%). Alternatively, differing slit losses for different lines can have a large impact on the results, emphasizing the importance of measuring all three lines with a consistent spectroscopic aperture. We conclude that, while the three-line approach to constraining the shape of the dust attenuation law in individual galaxies is promising, deep observations and a consistent observational strategy will be required to minimize observational biases and to disentangle the astrophysically interesting effect of differing covering fractions. The James Webb Space Telescope will provide more sensitive measurements of Balmer and Paschen lines for galaxies at z ≈ 0.3-2, enabling uniform constraints on the optical-infrared dust attenuation law and its intrinsic variation.

Keywords: Interstellar dust, Emission line galaxies, Interstellar dust extinction, Astrophysical dust processes, Galaxies
On the Use of CHIME to Detect Long-duration Radio Transients from Neutron Star Mergers. The short gamma-ray burst (SGRB) GRB 170817A was found to be related to a binary neutron star (BNS) merger. It is uncertain whether all SGRBs are caused by BNS mergers and also under what conditions a BNS merger can cause an SGRB. As BNS mergers can cause SGRBs, afterglow observations will also provide an alternative measurement of the BNS merger rate independent of gravitational-wave observations. In previous work by Feng et al., the feasibility of the detection of afterglows was considered using a variety of radio observatories and a simple flux threshold detection algorithm. Here, we consider a more sophisticated detection algorithm for SGRB afterglows and provide an estimate of the trials factors for a realistic search to obtain an updated estimate of the possibility of observing afterglows with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). We estimate 893 and 312 afterglows per year can be detected using a 3σ confidence level threshold with two jet models, one with half-opening angle uniformly distributed in 6°-30° and the other uniformly distributed in 3°-8° with the median of 6°. We also find that 88% and 98%, respectively, of the detectable afterglows for each jet-opening distribution are off axis, which are candidates for orphan afterglows. Our result predicts fewer detectable sources per year than the earlier analysis but confirms the essential conclusion that using CHIME to search for afterglows will be effective in constraining the astrophysical merger rate.

Keywords: Neutron stars, Gamma-ray bursts, Radio astronomy
Dust Dynamics in Transitional Disks: Clumping and Disk Recession. The role of radiation pressure in dust migration and the opening of inner cavities in transitional disks is revisited in this paper. Dust dynamics including radiation pressure is often studied in axisymmetric models, but in this work, we show that highly non-axisymmetric features can arise from an instability at the inner disk edge. Dust grains clump into high density features there, allowing radiation to leak around them and penetrate deeper into the disk, changing the course of dust migration. Our proof-of-concept, two-dimensional, vertically averaged simulations show that the combination of radiation pressure, shadowing, and gas drag can produce a net outward migration, or recession, of the dust component of the disk. The recession speed of the inner disk edge is on the order of 10-5 times Keplerian speed in our parameter space, which is faster than the background viscous flow, assuming a Shakura-Sunyaev viscosity α ≲ 10-3. This speed, if sustained over the lifetime of the disk, can result in a dust cavity as large as tens of astronomical units.

Keywords: Astronomical simulations, Astrophysical dust processes, Protoplanetary disks, Circumstellar dust, Planet formation
Understanding How Fast Black Holes Spin by Analyzing Data from the Second Gravitational-wave Catalogue. The Advanced LIGO and Virgo detectors have now observed approximately 50 black hole binary mergers, from which we can begin to infer how rapidly astrophysical black holes spin. The LIGO-Virgo Collaboration (LVC) analysis of detections up to the end of the first half of the third observing run (O3a) appeared to uncover a distribution of spin magnitudes that peaks at ~0.2. This is surprising: is there a black hole formation mechanism that prefers a particular, nonzero spin magnitude, or could this be the cumulative effect of multiple formation processes? We perform an independent analysis of the most recent gravitational-wave (GW) catalog, and find that (a) the support for the LVC spin magnitude is tenuous; in particular, adding or removing just one signal from the catalog can remove the statistical preference for this distribution; and (b) we find potential evidence for two spin subpopulations in the observed black holes: one with extremely low spins and one with larger spin magnitudes. We make the connection that these spin subpopulations could be correlated with the mass of the binary, with more massive binaries preferring larger spin magnitudes, and argue that this may provide evidence for hierarchical mergers in the second GW catalog.

Keywords: Black hole physics, Gravitational waves
Cluster Formation in GGD 12-15: Infall Motion with Rotation of the Natal Clump. We report results of observations of the GGD 12-15 region, where cluster formation is actively taking place, using various molecular emission lines. The C18O (J = 1-0) emission line reveals a massive clump in the region with a mass of ~2800 M ⊙ distributed over ~2 pc. The distribution of the C18O (J = 3-2) emission is similar to that of a star cluster forming therein, with an elliptical shape of ~1 pc in size. A bipolar molecular outflow driven by IRS 9Mc, a constituent star of the cluster, is blowing in the direction perpendicular to the elongated C18O (J = 3-2) distribution, covering the entire clump. There is a massive core with a radius of 0.3 pc and a mass of 530 M ⊙ in the center of the clump. There are two velocity components around the core, which are prominent in a position-velocity (PV) diagram along the major axis of the clump. In addition, a PV diagram along the minor axis of the clump, which is parallel to the outflow, shows a velocity gradient opposite to that of the outflow. The velocity structure strongly indicates the infalling motion of the clump. Comparison of the observational data with a simple model of infalling oblate clumps indicates that the clump is undergoing gravitational contraction with rotation.

Keywords: Interstellar molecules, Molecular gas, Radio astronomy, Interstellar dynamics, Star forming regions, Young star clusters, Molecular clouds, Stellar winds, H II regions
Using the Optical-NIR Spectral Energy Distributions to Search for the Evidence of Dust Formation of 66 Supernovae. In this paper, we searched for the dust formation evidence of 66 supernovae (SNe) by using the blackbody model and the blackbody plus dust emission model to fit their early-time optical-near-infrared (NIR) spectral energy distributions (SEDs). We find that, while the blackbody model can fit most SEDs of the SNe in our sample, the model cannot fit the SEDs of some SNe in which the SEDs of two SNe (SNe 2010bq and 2012ca) show NIR excesses which can be attributed to the emission from the heated dust. We use the blackbody plus dust emission model to fit the SEDs showing NIR excesses, finding that both the graphite and silicate dust models can fit the SEDs, and the graphite model gets reasonable temperatures or better fits. Assuming that the dust is graphite, the best-fitting temperatures (masses) of the dust of SNe 2010bq and 2012ca are ~1300-1800 K (~0.1-3.4 ×10-4 M ⊙) and ~600-1000 K (~0.6-7.5 × 10-3 M ⊙), respectively. We compare the vaporization radii and the blackbody radii of the dust shells of the two SNe with the upper limits of the ejecta radii of the SNe at the first epochs, and demonstrate that the NIR excesses of the SEDs of the two SNe might be caused by the pre-existing dust.

Keywords: Circumstellar dust
Subaru/Hyper Suprime-Cam z-Broadband Excess Selection of Extreme Emission Line Galaxies at z &lt; 1. We present a search for extreme emission line galaxies (EELGs) at z &lt; 1 in the COSMOS and North Ecliptic Pole (NEP) fields with imaging from Subaru/Hyper Suprime-Cam (HSC) and a combination of new and existing spectroscopy. We select EELGs on the basis of substantial excess flux in the z broad band, which is sensitive to Hα at 0.3 ≲ z ≲ 0.42 and [O III]λ5007 at 0.7 ≲ z ≲ 0.86. We identify 10,470 galaxies with zexcesses in the COSMOS data set and 91,385 in the NEP field. We cross-reference the COSMOS EELG sample with the zCOSMOS and DEIMOS 10k spectral catalogs, finding 1395 spectroscopic matches. We made an additional 71 (46 unique) spectroscopic measurements with Y &lt; 23 using the HYDRA multiobject spectrograph on the WIYN 3.5 m telescope, and 204 spectroscopic measurements from the DEIMOS spectrograph on the Keck II telescope, providing a total of 1441/10,470 spectroscopic redshifts for the EELG sample in COSMOS (~14%). We confirm that 1418 (~98%) are Hα or [O III]λ5007 emitters in the above stated redshift ranges. We also identify 240 redshifted Hα and [O III]λ5007 emitters in the NEP using spectra taken with WIYN/HYDRA and Keck/DEIMOS. Using broadband-selection techniques in the g - r - i color space, we distinguish between Hα and [O III]λ5007 emitters with 98.6% accuracy. We test our EELG selection by constructing Hα and [O III]λ5007 luminosity functions and comparing to recent literature results. We conclude that broadband magnitudes from HSC, the Vera C. Rubin Observatory, and other deep optical multiband surveys can be used to select EELGs in a straightforward manner.

Keywords: Broad band photometry, Galaxy evolution, Emission line galaxies
The Role of Neutral Hydrogen in Setting the Abundances of Molecular Species in the Milky Way's Diffuse Interstellar Medium. I. Observational Constraints from ALMA and NOEMA. We have complemented existing observations of H I absorption with new observations of HCO+, C2H, HCN, and HNC absorption from the Atacama Large Millimeter/submillimeter Array and the Northern Extended Millimeter Array in the directions of 20 background radio continuum sources with 4° ≤ ∣b∣ ≤ 81° to constrain the atomic gas conditions that are suitable for the formation of diffuse molecular gas. We find that these molecular species form along sightlines where A  V  ≳ 0.25, consistent with the threshold for the H I-to-H2 transition at solar metallicity. Moreover, we find that molecular gas is associated only with structures that have an H I optical depth &gt;0.1, a spin temperature &lt;80 K, and a turbulent Mach number ≳ 2. We also identify a broad, faint component to the HCO+ absorption in a majority of sightlines. Compared to the velocities where strong, narrow HCO+ absorption is observed, the H I at these velocities has a lower cold neutral medium fraction and negligible CO emission. The relative column densities and linewidths of the different molecular species observed here are similar to those observed in previous experiments over a range of Galactic latitudes, suggesting that gas in the solar neighborhood and gas in the Galactic plane are chemically similar. For a select sample of previously observed sightlines, we show that the absorption line profiles of HCO+, HCN, HNC, and C2H are stable over periods of ~3 yr and ~25 yr, likely indicating that molecular gas structures in these directions are at least ≳100 au in size.

Keywords: Interstellar phases, Interstellar atomic gas, Interstellar absorption, Diffuse molecular clouds
Snails across Scales: Local and Global Phase-mixing Structures as Probes of the Past and Future Milky Way. Signatures of vertical disequilibrium have been observed across the Milky Way's (MW's) disk. These signatures manifest locally as unmixed phase spirals in z-v  z  space ("snails-in-phase"), and globally as nonzero mean z and v  z , wrapping around the disk into physical spirals in the x-y plane ("snails-in-space"). We explore the connection between these local and global spirals through the example of a satellite perturbing a test-particle MW-like disk. We anticipate our results to broadly apply to any vertical perturbation. Using a z-v  z  asymmetry metric, we demonstrate that in test-particle simulations: (a) multiple local phase-spiral morphologies appear when stars are binned by azimuthal action J  ϕ , excited by a single event (in our case, a satellite disk crossing); (b) these distinct phase spirals are traced back to distinct disk locations; and (c) they are excited at distinct times. Thus, local phase spirals offer a global view of the MW's perturbation history from multiple perspectives. Using a toy model for a Sagittarius (Sgr)-like satellite crossing the disk, we show that the full interaction takes place on timescales comparable to orbital periods of disk stars within R ≲ 10 kpc. Hence such perturbations have widespread influence, which peaks in distinct regions of the disk at different times. This leads us to examine the ongoing MW-Sgr interaction. While Sgr has not yet crossed the disk (currently, z Sgr ≈ -6 kpc, v  z,Sgr ≈ 210 km s-1), we demonstrate that the peak of the impact has already passed. Sgr's pull over the past 150 Myr creates a global v  z  signature with amplitude ∝ M Sgr, which might be detectable in future spectroscopic surveys.

Keywords: Galaxy dynamics, Milky Way dynamics
The Accretion Process in the DQ Tau Binary System. Mass accretion from the circumstellar disk onto the protostar is a fundamental process during star formation. Measuring the mass accretion rate is particularly challenging for stars belonging to binary systems, because it is often difficult to discriminate which component is accreting. DQ Tau is an almost equal-mass spectroscopic binary system where the components orbit each other every 15.8 days. The system is known to display pulsed accretion, i.e., the periodic modulation of the accretion by the components on eccentric orbit. We present multi-epoch ESO/Very Large Telescope X-Shooter observations of DQ Tau, with the aim of determining which component of this system is the main accreting source. We use the absorption lines in the spectra to determine the radial velocity of the two components, and measure the continuum veiling as a function of wavelength and time. We fit the observed spectra with nonaccreting templates to correct for the photospheric and chromospheric contribution. In the corrected spectra, we study in detail the profiles of the emission lines and calculate mass accretion rates for the system as a function of orbital phase. In accordance with previous findings, we detect elevated accretion close to periastron. We measure the accretion rate as varying between 10-8.5 and 10-7.3 M ☉ yr-1. The emission line profiles suggest that both stars are actively accreting, and the dominant accretor is not always the same component, varying in a few orbits.

Keywords: Spectroscopic binary stars, Young stellar objects, Stellar accretion, Circumstellar disks, Stellar accretion disks, Spectroscopy
Intensity and Polarization Characteristics of Extended Neutron Star Surface Regions. The surfaces of neutron stars are sources of strongly polarized soft X-rays due to the presence of strong magnetic fields. Radiative transfer mediated by electron scattering and free-free absorption is central to defining local surface anisotropy and polarization signatures. Scattering transport is strongly influenced by the complicated interplay between linear and circular polarizations. This complexity has been captured in a sophisticated magnetic Thomson scattering simulation we recently developed to model the outer layers of fully ionized atmospheres in such compact objects, heretofore focusing on case studies of localized surface regions. Yet, the interpretation of observed intensity pulse profiles and their efficacy in constraining key neutron star geometry parameters is critically dependent upon adding up emission from extended surface regions. In this paper, intensity, anisotropy, and polarization characteristics from such extended atmospheres, spanning considerable ranges of magnetic colatitudes, are determined using our transport simulation. These constitute a convolution of varied properties of Stokes parameter information at disparate surface locales with different magnetic field strengths and directions relative to the local zenith. Our analysis includes full general relativistic propagation of light from the surface to an observer at infinity. The array of pulse profiles for intensity and polarization presented highlights how powerful probes of stellar geometry are possible. Significant phase-resolved polarization degrees in the range of 10%-60% are realized when summing over a variety of surface field directions. These results provide an important background for observations to be acquired by NASA's new Imaging X-ray Polarimetry Explorer X-ray polarimetry mission.

Keywords: Neutron stars, Magnetars, Magnetic fields