Sazuna/UAT_keywords huggingface dataset:
Highly Embedded 8 μm cores of Star Formation in the Spiral Arms and Filaments of 15 Nearby Disk Galaxies. Spitzer Space Telescope observations of 15 spiral galaxies show numerous dense cores at 8 μm that are revealed primarily in unsharp mask images. The cores are generally invisible in optical bands because of extinction, and they are also indistinct at 8 μm alone because of contamination by more widespread diffuse emission. Several hundred core positions, magnitudes, and colors from the four InfraRed Array Camera bands are measured and tabulated for each galaxy. The larger galaxies, which tend to have longer and more regular spiral arms, often have their infrared cores aligned along these arms, with additional cores in spiral arm spurs. Galaxies without regular spirals have their cores in more irregular spiral-like filaments, with typically only one or two cores per filament. Nearly every elongated emission feature has 8 μm cores strung out along its length. The occurrence of dense cores in long and thin filaments is reminiscent of filamentary star formation in the solar neighborhood, although on a scale 100 times larger in galaxies. The cores most likely form by gravitational instabilities and cloud agglomeration in the filaments. The simultaneous occurrence of several cores with regular spacings in some spiral arms suggests that in these cases, all of the cores formed at about the same time and the corresponding filaments are young. Total star formation rates for the galaxies correlate with the total embedded stellar masses in the cores with an average ratio corresponding to a possible age between 0.2 and 2 Myr. This suggests that the identified cores are the earliest phase for most star formation.

Keywords: Interstellar filaments, Star forming regions, Galaxy structure, Spiral arms, Interstellar absorption, Star formation, Interstellar clouds, Interstellar medium, Protostars
Swift-XRT Follow-up of Gravitational-wave Triggers in the Second Advanced LIGO/Virgo Observing Run. The Neil Gehrels Swift Observatory carried out prompt searches for gravitational-wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run (“O2”). Swift performed extensive tiling of eight LVC triggers, two of which had very low false-alarm rates (GW170814 and the epochal GW170817), indicating a high confidence of being astrophysical in origin; the latter was the first GW event to have an electromagnetic counterpart detected. In this paper we describe the follow-up performed during O2 and the results of our searches. No GW electromagnetic counterparts were detected; this result is expected, as GW170817 remained the only astrophysical event containing at least one neutron star after LVC’s later retraction of some events. A number of X-ray sources were detected, with the majority of identified sources being active galactic nuclei. We discuss the detection rate of transient X-ray sources and their implications in the O2 tiling searches. Finally, we describe the lessons learned during O2 and how these are being used to improve the Swift follow-up of GW events. In particular, we simulate a population of gamma-ray burst afterglows to evaluate our source ranking system’s ability to differentiate them from unrelated and uncataloged X-ray sources. We find that ≈60%-70% of afterglows whose jets are oriented toward Earth will be given high rank (i.e., “interesting” designation) by the completion of our second follow-up phase (assuming that their location in the sky was observed), but that this fraction can be increased to nearly 100% by performing a third follow-up observation of sources exhibiting fading behavior.

Keywords: Gamma-ray bursts, Surveys, Astronomy data analysis, Gravitational wave sources, Gravitational waves, X-ray sources, X-ray surveys, Catalogs
The Outer Rim Simulation: A Path to Many-core Supercomputers. We describe the Outer Rim cosmological simulation, one of the largest high-resolution N-body simulations performed to date, aimed at promoting science to be carried out with large-scale structure surveys. The simulation covers a volume of (4.225 Gpc)3 and evolves more than one trillion particles. It was executed on Mira, a BlueGene/Q system at the Argonne Leadership Computing Facility. We discuss some of the computational challenges posed by a system such as Mira, a many-core supercomputer, and how the simulation code, Hardware/Hybrid Accelerated Cosmology Code, has been designed to overcome these challenges. We have carried out a large range of analyses on the simulation data and we report on the results as well as the data products that have been generated. The full data set generated by the simulation totals more than 5 PB of data, making curation and handling of the data a large challenge in itself. The simulation results have been used to generate synthetic catalogs for large-scale structure surveys, including Dark Energy Spectroscopic Instrument and eBOSS, as well as experiments on the cosmic microwave background. A detailed catalog for the data challenges of the Large Synoptic Survey Telescope Dark Energy Science Collaboration has been created as well. We publicly release some of the Outer Rim halo catalogs, downsampled particle information, and lightcone data.

Keywords: N-body simulations
Extended Catalog of Winged or X-shaped Radio Sources from the FIRST Survey. We present a catalog of 290 “winged” or X-shaped radio galaxies (XRGs) extracted from the latest (2014 December 17) data release of the “Very Large Array Faint Images of the Radio Sky at Twenty centimeter.” We have combined these radio images with their counterparts in the TIFR GMRT sky survey at 150 MHz, in an attempt to identify any low surface brightness radio emission present in these sources. This has enabled us to assemble a sample of 106 “strong” XRG candidates and 184 “probable” XRG candidates whose XRG designation needs to be verified by further observations. The present sample of 290 XRG candidates is almost twice as large as the number of XRGs currently known. Twenty-five of our 290 XRG candidates (9 “strong” and 16 “probable”) are identified as quasars. Double-peaked narrow emission lines are seen in the optical spectra of three of the XRG candidates (two “strong” and one “probable”). Nearly 90% of the sample is located in the FR II domain of the Owen-Ledlow diagram. A few of the strong XRG candidates have a rather flat radio spectrum (spectral index α flatter than -0.3) between 150 MHz and 1.4 GHz, or between 1.4 and 5 GHz. Since this is not expected for lobe-dominated extragalactic radio sources (like nearly all known XRGs), these sources are particularly suited for follow-up radio imaging and near-simultaneous measurement of the radio spectrum.

Keywords: Jets, Quasars, Surveys, Active galactic nuclei, Radio continuum emission, Catalogs
Optical Polarimetric and Multiwavelength Flaring Activity of Blazar 3C 279. An exhaustive analysis of 9 yr optical R-band photopolarimetric data of the flat-spectrum radio quasar 3C 279 from 2008 February 27 to 2017 May 25 is presented, along with multiwavelength observing campaigns performed during the flaring activity exhibited in 2009 February/March, 2011 June, 2014 March/April, 2015 June, and 2017 February. In the R band, this source showed the maximum brightness state of 13.68 ± 0.11 mag (1.36 ± 0.20 mJy) on 2017 March 2 and the lowest brightness state ever recorded of 18.20 ± 0.87 mag (0.16 ± 0.03 mJy) on 2010 June 17. During the entire period of observations, the polarization degree varied between 0.48% ± 0.17% and 31.65% ± 0.77%, and the electric vector position angle (EVPA) exhibited large rotations between 82.°98 ± 0.°92 and 446.°32 ± 1.°95. Optical polarization data show that this source has a stable polarized component that varied from ∼6% (before the 2009 flare) to ∼13% after the flare. The overall behavior of our polarized variability data supports the scenario of jet precessions as responsible for the observed large rotations of the EVPA. Discrete correlation function analysis shows that the lags between gamma-rays and X-rays compared to the optical R-band fluxes are Δt ∼ 31 days and 1 day in 2009. Lags were also found among gamma-rays compared with X-rays and radio of Δt ∼ 30 and 43 days in 2011, and among radio and optical R band of Δt ∼ 10 days in 2014. A very intense flare in 2017 was observed in optical bands, with a dramatic variation in the polarization degree (from ∼6% to 20%) in 90 days without exhibiting flaring activity in other wavelengths.

Keywords: Quasars, Optical telescopes, Gamma-ray astronomy, Polarimetry
Mass Assembly of Stellar Systems and Their Evolution with the SMA (MASSES)—Full Data Release. We present and release the full data set for the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. This survey used the Submillimeter Array (SMA) to image the 74 known protostars within the Perseus molecular cloud. The SMA was used in two array configurations to capture outflows for scales &gt;30″ (&gt;9000 au) and to probe scales down to ∼1″ (∼300 au). The protostars were observed with the 1.3 mm and 850 μm receivers simultaneously to detect continuum at both wavelengths and molecular line emission from CO(2-1), 13CO(2-1), C18O(2-1), N2D+(3-2), CO(3-2), HCO+(4-3), and H13CO+(4-3). Some of the observations also used the SMA’s recently upgraded correlator, SWARM, whose broader bandwidth allowed for several more spectral lines to be observed (e.g., SO, H2CO, DCO+, DCN, CS, CN). Of the main continuum and spectral tracers observed, 84% of the images and cubes had emission detected. The median C18O(2-1) line width is ∼1.0 km s-1, which is slightly higher than those measured with single-dish telescopes at scales of 3000-20,000 au. Of the 74 targets, six are suggested to be first hydrostatic core candidates, and we suggest that L1451-mm is the best candidate. We question a previous continuum detection toward L1448 IRS2E. In the SVS 13 system, SVS 13A certainly appears to be the most evolved source, while SVS 13C appears to be hotter and more evolved than SVS 13B. The MASSES survey is the largest publicly available interferometric continuum and spectral line protostellar survey to date, and is largely unbiased as it only targets protostars in Perseus. All visibility (uv) data and imaged data are publicly available at https://dataverse.harvard.edu/dataverse/full_MASSES/.

Keywords: Surveys, Stellar jets, Molecular clouds, Dense interstellar clouds, Young stellar objects, Star formation, Protostars
Spectra of Ni V and Fe V in the Vacuum Ultraviolet. This work presents 97 remeasured Fe V wavelengths (1200-1600 Å) and 123 remeasured Ni V wavelengths (1200-1400 Å) with uncertainties of approximately 2 mÅ. An additional 67 remeasured Fe V wavelengths and 72 remeasured Ni V wavelengths with uncertainties greater than 2 mÅ are also reported. A systematic calibration error is also identified in the previous Ni V wavelengths and is corrected in this work. Furthermore, a new energy level optimization of Ni V is presented that includes level values as well as Ritz wavelengths. This work improves upon the available data used for observations of quadruply ionized nickel (Ni V) in white dwarf stars. This compilation is specifically targeted toward observations of the G191-B2B white dwarf spectrum that has been used to test for variations in the fine structure constant, α, in the presence of strong gravitational fields. The laboratory wavelengths for these ions were thought to be the cause of inconsistent conclusions regarding the variation limit of α as observed through the white dwarf spectrum. These inconsistencies can now be addressed with the improved laboratory data presented here.

Keywords: Spectral line lists, Line positions, Atomic physics, White dwarf stars, Laboratory astrophysics, Ultraviolet astronomy, Atomic spectroscopy
Evolution of the Cool Gas in the Circumgalactic Medium of Massive Halos: A Keck Cosmic Web Imager Survey of Lyα Emission around QSOs at z ≈ 2. Motivated by the recent discovery of the near-ubiquity of Lyα emission around z ≳ 3 QSOs, we performed a systematic study of QSO circumgalactic Lyα emission at z ≈ 2 utilizing the unique capability of the Keck Cosmic Web Imager (KCWI)—a new wide-field, blue sensitive integral field spectrograph. In this paper, we present KCWI observations of a sample of 16 ultraluminous Type I QSOs at z = 2.1-2.3 with ionizing luminosities of {L}{ν LL}}={10}31.1-32.3 erg s-1 Hz-1. We found that 14 out of 16 QSOs are associated with Lyα nebulae with projected linear sizes larger than 50 physical kpc. Among them, four nebulae have enormous Lyα emission with a Lyα surface brightness (SB) {SB}}Lyα }&gt; {10}-17 erg s-1 cm-2 arcsec-2 on the &gt;100 kpc scale, extending beyond the field of view of KCWI. Our KCWI observations reveal that most z ≈ 2 QSO nebulae have a more irregular morphology compared to those at z ≳ 3. In turn, we measure that the circularly averaged SB at z ≈ 2 is 0.4 dex fainter than the redshift-corrected median SB at z ≳ 3. The Lyα SB profile (SBLyα ) of QSOs at z ≈ 2 can be described by a power law of {SB}}Lyα ,z≈ 2.3}=3.7× {10}-17× {(r/40)}-1.8 erg s-1 cm-2 arcsec-2, with a slope similar to that at z ≳ 3. The observed lower redshift-corrected, circularly averaged SB may be mainly due to the lower covering factor of cool gas clouds in massive halos at z ≈ 2.

Keywords: Galaxy dark matter halos, Quasars, Cool intergalactic medium, Diffuse nebulae, Gaseous nebulae, Circumgalactic medium, Warm-hot intergalactic medium, High-redshift galaxies
Electron Energy Partition across Interplanetary Shocks. II. Statistics. A statistical analysis of 15,210 electron velocity distribution function (VDF) fits, observed within ±2 hr of 52 interplanetary (IP) shocks by the Wind spacecraft near 1 au, is presented. This is the second in a three-part series on electron VDFs near IP shocks. The electron velocity moment statistics for the dense, low-energy core, tenuous, hot halo, and field-aligned beam/strahl are a statistically significant list of values illustrated with both histograms and tabular lists for reference and baselines in future work. Given the large statistics in this investigation, the beam/strahl fit results in the upstream are now the most comprehensive attempt to parameterize the beam/strahl electron velocity moments in the ambient solar wind. The median density, temperature, beta, and temperature anisotropy values for the core(halo)[beam/strahl] components, with subscripts ec(eh)[eb], of all fit results, respectively, are {n}ec(h)[b]}∼ 11.3(0.36)[0.17] {cm}}-3, {T}ec(h)[b],{tot}}∼ 14.6(48.4)[40.2] {eV}, {β }ec(h)[b],{tot}}∼ 0.93(0.11)[0.05], and {{ \mathcal A }}ec(h)[b]} ∼ 0.98(1.03)[0.93]. This work will also serve as a 1 au baseline and reference for missions like Parker Solar Probe and Solar Orbiter.

Keywords: Space plasmas, Interplanetary shocks, Plasma physics, Solar wind, Plasma astrophysics, Solar coronal mass ejection shocks, Interplanetary particle acceleration, Solar coronal mass ejections
The WISE Extended Source Catalog (WXSC). I. The 100 Largest Galaxies. We present mid-infrared photometry and measured global properties of the 100 largest galaxies in the sky, including the well-studied Magellanic Clouds, Local Group galaxies M31 and M33, the Fornax and Virgo galaxy cluster giants, and many of the most spectacular Messier objects (e.g., M51 and M83). This is the first release of a larger catalog of extended sources as imaged in the mid-infrared, called the Wide-field Infrared Survey Explorer (WISE) Extended Source Catalog (WXSC). In this study, we measure their global attributes, including integrated flux, surface brightness, and radial distribution. The largest of the large are the LMC, SMC, and Andromeda galaxy, which are also the brightest mid-infrared galaxies in the sky. We interrogate the large galaxies using WISE colors, which serve as proxies for four general types of galaxies: bulge-dominated spheroidals, intermediate semi-quiescent disks, star-forming (SF) spirals, and AGN-dominated. The colors reveal a tight “sequence” that spans 5 mag in W2-W3 color, ranging from early to late types and low to high SF activity; we fit the functional form given by (W1-W2)=≤ft[0.015× {e}\tfrac{(W2-W3){1.38}}\right]-0.08. Departures from this sequence may reveal nuclear, starburst, and merging events. Physical properties and luminosity attributes are computed, notably the diameter, aggregate stellar mass, and dust-obscured star formation activity. To effectively study and compare these galaxy characteristics, we introduce the “pinwheel” diagram, which depicts physical properties with respect to the median value observed for WISE galaxies in the local universe. Utilized with the WXSC, this diagram will delineate between different kinds of galaxies, identifying those with similar star formation and structural properties. Finally, we present the mid-infrared photometry of the 25 brightest globular clusters in the sky, of which many are also the largest and brightest objects orbiting the Milky Way, including Omega Centauri, 47 Tucanae, and a number of famed night-sky targets (e.g., M13).

Keywords: Sky surveys, Catalogs, Galaxy evolution, Infrared galaxies, Galaxy processes
CosmoDC2: A Synthetic Sky Catalog for Dark Energy Science with LSST. This paper introduces cosmoDC2, a large synthetic galaxy catalog designed to support precision dark energy science with the Large Synoptic Survey Telescope (LSST). CosmoDC2 is the starting point for the second data challenge (DC2) carried out by the LSST Dark Energy Science Collaboration (LSST DESC). The catalog is based on a trillion-particle, (4.225 Gpc)3 box cosmological N-body simulation, the Outer Rim run. It covers 440 deg2 of sky area to a redshift of z = 3 and matches expected number densities from contemporary surveys to a magnitude depth of 28 in the r band. Each galaxy is characterized by a multitude of galaxy properties including stellar mass, morphology, spectral energy distributions, broadband filter magnitudes, host halo information, and weak lensing shear. The size and complexity of cosmoDC2 requires an efficient catalog generation methodology; our approach is based on a new hybrid technique that combines data-based empirical approaches with semianalytic galaxy modeling. A wide range of observation-based validation tests has been implemented to ensure that cosmoDC2 enables the science goals of the planned LSST DESC DC2 analyses. This paper also represents the official release of the cosmoDC2 data set, including an efficient reader that facilitates interaction with the data.

Keywords: Cosmology, Dark energy, Galaxies, Large-scale structure of the universe
Science Opportunities from Observations of the Interstellar Neutral Gas with Adjustable Boresight Direction. The interstellar neutral (ISN) gas enters the heliosphere and is detected at a few au from the Sun, as demonstrated by Ulysses and the Interstellar Boundary Explorer (IBEX). Ulysses observed ISN gas from different vantage points in a polar orbit from 1994 to 2007, while IBEX has been observing in an Earth orbit in a fixed direction relative to the Sun from 2009. McComas et al. (2018) reported about an IMAP-Lo detector on board the Interstellar Mapping and Acceleration Probe (IMAP), with an ability to track the ISN flux in the sky. We present observation geometries for ISN gas for a detector with the capability to adjust the boresight direction along the Earth orbit over a year within a multichoice ISN observation scheme. We study science opportunities from the observations as a function of time during a year and the phase of solar activity. We identify observation geometries and determine the observation seasons separately for various ISN species and populations. We find that using an adjustable viewing direction allows for ISN gas observations in the upwind hemisphere, where the signal is not distorted by gravitational focusing, in addition to the viewing of ISN species throughout the entire year. Moreover, we demonstrate that with appropriately adjusted observation geometries, primary and secondary populations can be fully separated. Additionally, we show that atoms of ISN gas on indirect trajectories are accessible for detection, and we present their impact on the study of the ionization rates for ISN species.

Keywords: Interstellar medium, Interstellar medium wind, Heliosphere, Interstellar plasma
Asteroid Photometry from the Transiting Exoplanet Survey Satellite: A Pilot Study. The Transiting Exoplanet Survey Satellite (TESS) searches for planets transiting bright and nearby stars using high-cadence, large-scale photometric observations. Full frame images provided by the TESS mission include a large number of serendipitously observed main-belt asteroids (MBAs). Due to the cadence of the published full frame images, we are sensitive to periods as long as of order tens of days, a region of phase space that is generally not accessible through traditional observing. This work represents a much less biased measurement of the period distribution in this period range. We have derived rotation periods for 300 MBAs and have partial lightcurves for a further 7277 asteroids, including 43 with periods of P &gt; 100 hr; this large number of slow rotators is predicted by theory. Of these slow rotators we find none requiring significant internal strength to resist rotational reshaping. We find our derived rotation periods to be in excellent agreement with results in the Lightcurve Database for the 55 targets that overlap. Over the nominal two-year lifetime of the mission, we expect the detection of around 85,000 unique asteroids with rotation period solutions for around 6000 asteroids. We project that the systematic analysis of the entire TESS data set will increase the number of known slow-rotating asteroids (period &gt; 100 hr) by a factor of 10. Comparing our new period determinations with previous measurements in the literature, we find that the rotation period of asteroid (2320) Blarney has decreased by at least 20% over the past decade, potentially due to surface activity or subcatastrophic collisions.

Keywords: Main belt asteroids, Asteroids
The Origin of Cosmic Rays: How Their Composition Defines Their Sources and Sites and the Processes of Their Mixing, Injection, and Acceleration. Galactic cosmic-ray source compositions, (Z/H)GCRS from H to Pb and ∼108-1014 eV, differ from solar-local interstellar (Z/H)SS or (Z/H)ISM by ∼20-200×. Both are mostly just mixes of core-collapse (CCSN) and thermonuclear (SN Ia) supernova ejecta. The (Z/H)ISM comes from steady unbiased accumulation over gigayears. But the cosmic-ray mass mixing ratio, universal interstellar medium (ISM)/CCSN ∼4:1 of swept-up ISM, and ∼10× metallicity ejecta show that (Z/H)GCRS comes from basic Sedov-Taylor bulk mixing of homologous, expanding CCSNe in their OB-cluster self-generated superbubbles, further enriched by highly biased grain-sputtering injection during diffusive shock acceleration (DSA). Moreover, this mixing ratio now reveals that the cosmic rays are primarily accelerated as their evolving reverse-shock radius and energy pass through their maxima. Refractories and volatiles, first deposited in fast ejecta and ISM grains in freely expanding ejecta, are simultaneously Coulomb-sputtered F CS by turbulent H and He as suprathermal ions into DSA that carries them to cosmic-ray energies. This bulk mixing selectively increases source mix abundances (Z/H)SM/(Z/H)SS by ∼2-10, and injection by grain condensation and implantation fractions F GC by another ∼6, while Z 2/3-Coulomb grain sputtering enrichments F CS give an added ∼4-20. Applying these basic processes of mixing and injection to solar system (Z/H)SS produces grain-injected, source mix (Z/H)SMGI values that match major cosmic-ray abundances (Z/H)GCRS to ±35% with no free parameters. Independently confirming grain injection, we find (Z/H)GCRS shows no detectable contribution of Fe from SN Ia, although producing ∼1/2 Fe in the ISM, but there is also no dust in SN Ia remnants, unlike CCSNe.

Keywords: Interstellar dust, Cosmic rays, Interstellar abundances, Supernova remnants, Shocks, Superbubbles