Sazuna/UAT_keywords huggingface dataset:
Deuterated Polycyclic Aromatic Hydrocarbons in the Interstellar Medium: The C-D Band Strengths of Multideuterated Species. Observationally, the interstellar gas-phase abundance of deuterium (D) is considerably depleted and the missing D atoms are often postulated to have been locked up into carbonaceous solids and polycyclic aromatic hydrocarbon (PAH) molecules. An accurate knowledge of the fractional amount of D (relative to H) tied up in carbon dust and PAHs has important cosmological implications since D originated exclusively from the Big Bang and the present-day D abundance, after accounting for the astration it has experienced during Galactic evolution, provides essential clues to the primordial nucleosynthesis and the cosmological parameters. To quantitatively explore the extent to which PAHs could possibly accommodate the observed D depletion, we have previously quantum-chemically computed the infrared vibrational spectra of monodeuterated PAHs and derived the mean intrinsic band strengths of the 3.3 μm C-H stretch (A3.3) and the 4.4 μm C-D stretch (A4.4). Here we extend our previous work to multideuterated PAH species of different deuterations, sizes, and structures. We find that both the intrinsic band strengths A3.3 and A4.4 (on a per-unit-bond basis) and their ratios A4.4/A3.3 not only show little variation among PAHs of different deuterations, sizes, and structures, they are also closely similar to that of monodeuterated PAHs. Therefore, a PAH deuteration level (i.e., the fraction of peripheral atoms attached to C atoms in the form of D) of ~2.4% previously estimated from the observed 4.4 to 3.3 μm band ratio based on the A4.4/A3.3 ratio of monodeuterated PAHs is robust.

Keywords: Interstellar molecules, Interstellar line emission, Polycyclic aromatic hydrocarbons, Astrochemistry, Line intensities
A Deep-learning Approach for Live Anomaly Detection of Extragalactic Transients. There is a shortage of multiwavelength and spectroscopic follow-up capabilities given the number of transient and variable astrophysical events discovered through wide-field optical surveys such as the upcoming Vera C. Rubin Observatory and its associated Legacy Survey of Space and Time. From the haystack of potential science targets, astronomers must allocate scarce resources to study a selection of needles in real time. Here we present a variational recurrent autoencoder neural network to encode simulated Rubin Observatory extragalactic transient events using 1% of the PLAsTiCC data set to train the autoencoder. Our unsupervised method uniquely works with unlabeled, real-time, multivariate, and aperiodic data. We rank 1,129,184 events based on an anomaly score estimated using an isolation forest. We find that our pipeline successfully ranks rarer classes of transients as more anomalous. Using simple cuts in anomaly score and uncertainty, we identify a pure (≈95% pure) sample of rare transients (i.e., transients other than Type Ia, Type II, and Type Ibc supernovae), including superluminous and pair-instability supernovae. Finally, our algorithm is able to identify these transients as anomalous well before peak, enabling real-time follow-up studies in the era of the Rubin Observatory.

Keywords: Surveys, Astrostatistics techniques, Supernovae, Time series analysis
Study of the Prompt Emission of Short Gamma-Ray Bursts Using a Multicolor Blackbody: A Clue to the Viewing Angle. The prompt emission of short gamma-ray bursts (sGRBs) with known redshifts is analyzed using the model of a multicolor blackbody, which is interpreted as the emission from a nondissipative photosphere taking into account a power-law jet structure and the viewing geometry of the jet. We find nearly 69% and 26% of the sample is consistent with a multicolor blackbody and a pure blackbody model, respectively. Using this interpretation, we infer that nearly 57% (18%) of the sGRBs in our sample are observed within (or along the edge of) the jet core. The sGRB jets are deduced to possess a narrow core with a median θc ~ 3°. This suggests the rate of sGRBs that would be viewed within the jet core to be 1.8-26 Gpc-3 yr-1. The power-law index of the decreasing Lorentz factor profile of the jet structure is deduced to be 1.3-2.2. The intrinsic luminosity is found to range between 1048-1053 erg s-1. The average values of the Lorentz factor and nozzle radius of the sGRB jets are inferred to be 210 (85) and 107.7 (109.6) cm for the cases when the photosphere forms in the coasting (accelerating) phase, respectively. The viability of the inferred values of the different parameters of the GRB outflow and viewing geometry within this physical interpretation enhances the prospect of the photospheric emission model explaining the observed GRB spectrum.

Keywords: Burst astrophysics, Gamma-ray bursts, Gamma-ray transient sources
Methods of Error Estimation for Delay Power Spectra in 21 cm Cosmology. Precise measurements of the 21 cm power spectrum are crucial for understanding the physical processes of hydrogen reionization. Currently, this probe is being pursued by low-frequency radio interferometer arrays. As these experiments come closer to making a first detection of the signal, error estimation will play an increasingly important role in setting robust measurements. Using the delay power spectrum approach, we have produced a critical examination of different ways that one can estimate error bars on the power spectrum. We do this through a synthesis of analytic work, simulations of toy models, and tests on small amounts of real data. We find that, although computed independently, the different error bar methodologies are in good agreement with each other in the noise-dominated regime of the power spectrum. For our preferred methodology, the predicted probability distribution function is consistent with the empirical noise power distributions from both simulated and real data. This diagnosis is mainly in support of the forthcoming HERA upper limit and also is expected to be more generally applicable.

Keywords: Reionization, Radio interferometry, H I line emission
Atomic Transition Probabilities of Neutral Calcium. The goals of this study are (1) to test the best theoretical transition probabilities for Ca I (a relatively light alkaline earth spectrum) from a modern ab initio calculation using configuration interaction plus many-body perturbation theory against the best modern experimental transition probabilities and (2) to produce as accurate and comprehensive a line list of Ca I transition probabilities as is currently possible based on this comparison. We report new Ca I radiative lifetime measurements from a laser-induced fluorescence experiment and new emission branching fraction measurements from a 0.5 m focal length grating spectrometer with a detector array. We combine these data for upper levels that have both a new lifetime and new branching fractions to report log(gf) values for two multiplets consisting of nine transitions. Detailed comparisons are made between theory and experiment, including the measurements reported herein and a selected set of previously published experimental transition probabilities. We find that modern theory compares favorably to experimental measurements in most instances where such data exist. A final list of 202 recommended transition probabilities is presented, which covers lines of Ca I with wavelengths ranging from 2200 to 10000 Å. These are mostly selected from theory but are augmented with high-quality experimental measurements from this work and from the literature. The recommended transition probabilities are used in a redetermination of the Ca abundance in the Sun and in the metal-poor star HD 84937. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. The data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes. Other data have been obtained from the European Southern Observatory Science Archive Facility.

Keywords: Solar abundances, Atomic spectroscopy, Stellar abundances, Atomic data benchmarking
Evolution of Cold Gas at 2 &lt; z &lt; 5: A Blind Search for H I and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN. We present results from a spectroscopically blind search for associated and intervening H I 21 cm and OH 18 cm absorption lines toward 88 active galactic nuclei (AGN) at 2 ≤ z ≤ 5 using the uGMRT. The sample of AGN with 1.4 GHz spectral luminosity in the range 1027-29.3 W Hz-1 is selected using mid-infrared colors and closely resembles the distribution of the underlying quasar population. The search for associated or proximate absorption, defined to be within 3000 km s-1 of the AGN redshift, led to one H I 21 cm absorption detection (M1540-1453; zabs = 2.1139). This is only the fourth known absorption at z &gt; 2. The detection rate ( ${1.6}_{-1.4}^{+3.8}$ %) suggests a low covering factor of the cold neutral medium (CNM; T ~ 100 K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Lyα systems (DLAs), has comoving absorption path lengths of ΔX = 130.1 and 167.7 for H I and OH, respectively. The corresponding number of absorbers per unit comoving path length are ≤0.014 and ≤0.011, respectively. The former is at least 4.5 times lower than that of DLAs and consistent with the CNM cross section estimated using H2 and C I absorbers at z &gt; 2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path ~9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of H I 21 cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z &gt; 2.

Keywords: AGN host galaxies, Quasar absorption line spectroscopy, Active galaxies, Interstellar medium, Galaxies
The Palomar Transient Factory Core-collapse Supernova Host-galaxy Sample. I. Host-galaxy Distribution Functions and Environment Dependence of Core-collapse Supernovae. Several thousand core-collapse supernovae (CCSNe) of different flavors have been discovered so far. However, identifying their progenitors has remained an outstanding open question in astrophysics. Studies of SN host galaxies have proven to be powerful in providing constraints on the progenitor populations. In this paper, we present all CCSNe detected between 2009 and 2017 by the Palomar Transient Factory. This sample includes 888 SNe of 12 distinct classes out to redshift z ≍ 1. We present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. The galaxy mass function of Type Ic, Ib, IIb, II, and IIn SNe ranges from 105 to 1011.5 M☉, probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. Moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. Regular CCSNe are hence direct tracers of star formation. Small but notable differences exist between some of the SN classes. Type Ib/c SNe prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than Type IIb and II SNe. These differences are less pronounced than previously thought. H-poor superluminous supernovae (SLSNe) and SNe Ic-BL are scarce in galaxies above 1010 M☉. Their progenitors require environments with metallicities of &lt; 0.4 and &lt; 1 solar, respectively. In addition, the hosts of H-poor SLSNe are dominated by a younger stellar population than all other classes of CCSNe. Our findings corroborate the notion that low metallicity and young age play an important role in the formation of SLSN progenitors.

Keywords: Galaxies, Supernovae, Core-collapse supernovae, Galactic and extragalactic astronomy
A Quick Look at the 3 GHz Radio Sky. I. Source Statistics from the Very Large Array Sky Survey. The Very Large Array Sky Survey (VLASS) is observing the entire sky north of -40° in the S band (2 GHz &lt; ν &lt; 4 GHz), with the highest angular resolution (2"5) of any all-sky radio continuum survey to date. VLASS will cover its entire footprint over three distinct epochs, the first of which has now been observed in full. Based on Quick Look images from this first epoch, we have created a catalog of 1.9 × 106 reliably detected radio components. Due to the limitations of the Quick Look images, component flux densities are underestimated by ~15% at Speak &gt; 3 mJy beam-1 and are often unreliable for fainter components. We use this catalog to perform statistical analyses of the ν ~ 3 GHz radio sky. Comparisons with the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey show the typical 1.4-3 GHz spectral index, α, to be ~-0.71. The radio color-color distribution of point and extended components is explored by matching with FIRST and the LOFAR Two-meter Sky Survey. We present the VLASS source counts, dN/dS, which are found to be consistent with previous observations at 1.4 and 3 GHz. Resolution improvements over FIRST result in excess power in the VLASS two-point correlation function at angular scales ≲7″, and in 18% of active galactic nuclei associated with a single FIRST component being split into multicomponent sources by VLASS.

Keywords: Sky surveys, Radio galaxies, Radio astronomy, Radio source catalogs
MG1-688432: A Peculiar Variable System. The short-period variable star MG1-688432 has been discovered to exhibit occasional extremely high energy optical outbursts as high as 1038 erg. Outbursts are typically several hours in duration. These events are often highly structured, resembling sequential associated releases of energy. Twenty years of time sequence photometry are presented, indicating a basic sinusoidal light curve of mean period 6.65 days, with some phase shifting and long-term temporal trends in amplitude and mean brightness. Spectroscopy reveals a peculiar star, best resembling a K3 subgiant that has evolved off the main sequence moderately redward of the giant branch. Spectroscopic and radial velocity analyses indicate a binary system orbiting its barycenter with an unseen companion to the K3 IV primary. This is not an eclipsing system, with the inclination of the orbit precluding eclipse by the secondary. The system is at a distance of 1.5 kpc, and analysis of Gaia observations leads to the conclusion that the H-R diagram position of MG1-688432 is established by an intrinsic feature of the system, most likely either the stellar evolutionary state of the observed star or the presence of small (nongray) dust within the system. Two mechanisms (or combinations thereof) that might give rise to characteristics of the system are (1) magnetically induced chromospheric activity and (2) impacts with tidally disrupted planetary debris.

Keywords: Stellar chromospheres, Binary stars, Eruptive variable stars, K subgiant stars
The DECam Local Volume Exploration Survey: Overview and First Data Release. The DECam Local Volume Exploration survey (DELVE) is a 126-night survey program on the 4 m Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile. DELVE seeks to understand the characteristics of faint satellite galaxies and other resolved stellar substructures over a range of environments in the Local Volume. DELVE will combine new DECam observations with archival DECam data to cover ~15,000 deg2 of high Galactic latitude (∣b∣ &gt; 10°) southern sky to a 5σ depth of g, r, i, z ~ 23.5 mag. In addition, DELVE will cover a region of ~2200 deg2 around the Magellanic Clouds to a depth of g, r, i ~ 24.5 mag and an area of ~135 deg2 around four Magellanic analogs to a depth of g, i ~ 25.5 mag. Here, we present an overview of the DELVE program and progress to date. We also summarize the first DELVE public data release (DELVE DR1), which provides point-source and automatic aperture photometry for ~520 million astronomical sources covering ~5000 deg2 of the southern sky to a 5σ point-source depth of g = 24.3 mag, r = 23.9 mag, i = 23.3 mag, and z = 22.8 mag. DELVE DR1 is publicly available via the NOIRLab Astro Data Lab science platform.

Keywords: Local Group, Surveys, Dwarf galaxies, Magellanic Clouds, Catalogs
Census of High- and Medium-mass Protostars. V. CO Abundance and the Galactic X<SUB>CO</SUB> Factor. We present the second dust continuum data release in the Census of High- and Medium-mass Protostars (CHaMP), expanding the methodology trialed in Pitts et al. to the entire CHaMP survey area (280° &lt; ℓ &lt; 300°, - 4° &lt; b &lt; + 2°). This release includes maps of dust temperature (Td), H2 column density ( ${N}_{{{\rm{H}}}_{2}}$ ), gas-phase CO abundance, and temperature-density plots for every prestellar clump with Herschel coverage, showing no evidence of internal heating for most clumps in our sample. We show that CO abundance is a strong function of Td and can be fit with a second-order polynomial in log-space, with a typical dispersion of a factor of 2-3. The CO abundance peaks at ${20.0}_{-1.0}^{+0.4}$ K with a value of ${7.4}_{-0.3}^{+0.2}\times {10}^{-5}$ per H2; the low Td at which this maximal abundance occurs relative to laboratory results is likely due to interstellar UV bombardment in the largest survey fields. Finally, we show that, as predicted by theoretical literature and hinted at in previous studies of individual clouds, the conversion factor from integrated 12CO line intensity ( ${I}_{{}^{12}{\rm{CO}}}$ ) to ${N}_{{{\rm{H}}}_{2}}$ , the XCO factor, varies as a broken power law in ${I}_{{}^{12}{\rm{CO}}}$ with a transition zone between 70 and 90 K km s-1. The XCO function we propose has ${N}_{{{\rm{H}}}_{2}}\propto {I}_{{}^{12}{\rm{CO}}}^{0.51}$ for ${I}_{{}^{12}{\rm{CO}}}\lesssim 70$ K km s-1 and ${N}_{{{\rm{H}}}_{2}}\propto {I}_{{}^{12}{\rm{CO}}}^{2.3}$ for ${I}_{{}^{12}{\rm{CO}}}\gtrsim 90$ K km s-1. The high- ${I}_{{}^{12}{\rm{CO}}}$ side should be generalizable with known adjustments for metallicity, but the influence of interstellar UV fields on the low- ${I}_{{}^{12}{\rm{CO}}}$ side may be sample specific. We discuss how these results expand on previous works in the CHaMP series and help tie together observational, theoretical, and laboratory studies on CO over the past decade.

Keywords: Star forming regions, Circumstellar matter, Milky Way disk, Young stellar objects, Dust continuum emission, Star formation, Interstellar medium, CO line emission, Protostars, Circumstellar dust
Searching for Low-redshift Faint Galaxies with MMT/Hectospec. We present redshifts for 2753 low-redshift galaxies between 0.03 ≲ zspec ≲ 0.5 with 18 ≤ r ≤ 22 obtained with Hectospec at the Multi-Mirror Telescope. The observations targeted the XMM-LSS, ELAIS-N1 and DEEP2-3 fields, each of which covers ~1 deg2. These fields are also part of the recently completed Canada-France-Hawaii Telescope Large Area U-band Deep Survey and ongoing Hyper Suprime-Cam deep fields surveys. The efficiency of our technique for selecting low-redshift galaxies is confirmed by the redshift distribution of our sources. In addition to redshifts, these high signal-to-noise ratio spectra are used to measure ages, metallicities, and nuclear activity levels. In combination with the photometric catalog in u, g, r, i, z, y down to 27 AB mag, we are able to study the galaxy population down to stellar masses of ~108 M⊙. This paper presents the observational strategy, the reduction procedure and properties of the galaxy sample. (The catalog can be accessed through the survey's website at http://mips.as.arizona.edu/~cnaw/Faint_Low_z/.)

Keywords: Galaxy formation, Quenched galaxies, Dwarf galaxies, Spectroscopy, Redshift surveys, Post-starburst galaxies
Astro-COLIBRI-The COincidence LIBrary for Real-time Inquiry for Multimessenger Astrophysics. Astro-COLIBRI is a novel tool that evaluates alerts of transient observations in real time, filters them by user-specified criteria, and puts them into their multiwavelength and multimessenger context. Through fast generation of an overview of persistent sources as well as transient events in the relevant phase space, Astro-COLIBRI contributes to an enhanced discovery potential of both serendipitous and follow-up observations of the transient sky. The software's architecture comprises a Representational State Transfer Application Programming Interface, both a static and a real-time database, a cloud-based alert system, as well as a website and apps for iOS and Android as clients for users. The latter provide a graphical representation with a summary of the relevant data to allow for the fast identification of interesting phenomena along with an assessment of observing conditions at a large selection of observatories around the world.

Keywords: High energy astrophysics, Neutrino astronomy, Transient sources, Time domain astronomy, Gravitational waves, Gamma-ray transient sources
Knowledge Gaps in the Cometary Spectra of Oxygen-bearing Molecular Cations. Molecular cations are present in various astronomical environments, most notably in cometary atmospheres and tails where sunlight produces exceptionally bright near-UV to visible transitions. Such cations typically have longer-wavelength and brighter electronic emission than their corresponding neutrals. A robust understanding of their near-UV to visible properties would allow these cations to be used as tools for probing the local plasma environments or as tracers of neutral gas in cometary environments. However, full spectral models are not possible for characterization of small, oxygen-containing molecular cations given the body of molecular data currently available. The five simplest such species (H2O+, CO2+, CO+, OH+, and ${{\rm{O}}}_{2}^{+}$ ) are well characterized in some spectral regions but are lacking robust reference data in others. Such knowledge gaps hinder fully quantitative models of cometary spectra, specifically hindering accurate estimates of physical-chemical processes originating with the most common molecules in comets. Herein, the existing spectral data are collected for these molecules, and the places where future work is needed are highlighted, specifically where the lack of such data would greatly enhance the understanding of cometary evolution.

Keywords: Surveys, Comets, Molecular spectroscopy, Catalogs