Showing papers in "Astrophysical Journal Supplement Series in 2018"
Bela Abolfathi1, D. S. Aguado2, Gabriela Aguilar3, Carlos Allende Prieto2 +361 more•Institutions (94)
TL;DR: SDSS-IV is the fourth generation of the Sloan Digital Sky Survey and has been in operation since 2014 July. as discussed by the authors describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14).
Abstract: The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
965 citations
Kavli Institute for Theoretical Physics1, University of California, Santa Cruz2, University of California, Santa Barbara3, Kurchatov Institute4, Moscow State University5, Institute for the Physics and Mathematics of the Universe6, University of California, Berkeley7, Arizona State University8, University of Amsterdam9, Northwestern University10, University of Liège11, University of Wisconsin-Madison12
TL;DR: The Modules for Experiments in Stellar Astrophysics (MESA) software instrument as discussed by the authors has been updated with the capability to handle floating point exceptions and stellar model optimization, as well as four new software tools.
Abstract: We update the capabilities of the software instrument Modules for Experiments in Stellar Astrophysics (MESA) and enhance its ease of use and availability. Our new approach to locating convective boundaries is consistent with the physics of convection, and yields reliable values of the convective-core mass during both hydrogen- and helium-burning phases. Stars with become white dwarfs and cool to the point where the electrons are degenerate and the ions are strongly coupled, a realm now available to study with MESA due to improved treatments of element diffusion, latent heat release, and blending of equations of state. Studies of the final fates of massive stars are extended in MESA by our addition of an approximate Riemann solver that captures shocks and conserves energy to high accuracy during dynamic epochs. We also introduce a 1D capability for modeling the effects of Rayleigh–Taylor instabilities that, in combination with the coupling to a public version of the radiation transfer instrument, creates new avenues for exploring Type II supernova properties. These capabilities are exhibited with exploratory models of pair-instability supernovae, pulsational pair-instability supernovae, and the formation of stellar-mass black holes. The applicability of MESA is now widened by the capability to import multidimensional hydrodynamic models into MESA. We close by introducing software modules for handling floating point exceptions and stellar model optimization, as well as four new software tools— , -Docker, , and mesastar.org—to enhance MESA's education and research impact.
808 citations
TL;DR: The goal of this paper is to build intuition about what assumptions are implicit in the use of the Lomb-Scargle periodogram and related estimators of periodicity so as to motivate important practical considerations required in its proper application and interpretation.
Abstract: The Lomb-Scargle periodogram is a well-known algorithm for detecting and characterizing periodic signals in unevenly-sampled data. This paper presents a conceptual introduction to the Lomb-Scargle periodogram and important practical considerations for its use. Rather than a rigorous mathematical treatment, the goal of this paper is to build intuition about what assumptions are implicit in the use of the Lomb-Scargle periodogram and related estimators of periodicity, so as to motivate important practical considerations required in its proper application and interpretation.
666 citations
TL;DR: The first public data release of the DES DR1 dataset is described in this paper, consisting of reduced single-epoch images, co-add images, and co-added source catalogs, and associated products and services.
Abstract: We describe the first public data release of the Dark Energy Survey, DES DR1, consisting of reduced single-epoch images, co-added images, co-added source catalogs, and associated products and services assembled over the first 3 yr of DES science operations. DES DR1 is based on optical/near-infrared imaging from 345 distinct nights (2013 August to 2016 February) by the Dark Energy Camera mounted on the 4 m Blanco telescope at the Cerro Tololo InterAmerican Observatory in Chile. We release data from the DES wide-area survey covering similar to 5000 deg(2) of the southern Galactic cap in five broad photometric bands, grizY. DES DR1 has a median delivered point-spread function of g = 1.12, r = 0.96, i = 0.88, z = 0.84, and Y = 0.'' 90 FWHM, a photometric precision of <1% in all bands, and an astrometric precision of 151 mas. The median co-added catalog depth for a 1.'' 95 diameter aperture at signal-to-noise ratio (S/N) = 10 is g = 24.33, r = 24.08, i = 23.44, z = 22.69, and Y = 21.44 mag. DES DR1 includes nearly 400 million distinct astronomical objects detected in similar to 10,000 co-add tiles of size 0.534 deg(2) produced from similar to 39,000 individual exposures. Benchmark galaxy and stellar samples contain similar to 310 million and similar to 80 million objects, respectively, following a basic object quality selection. These data are accessible through a range of interfaces, including query web clients, image cutout servers, jupyter notebooks, and an interactive co-add image visualization tool. DES DR1 constitutes the largest photometric data set to date at the achieved depth and photometric precision.
506 citations
Goddard Space Flight Center1, Cornell University2, West Virginia University3, Pennsylvania State University4, Notre Dame of Maryland University5, Montana State University6, Franklin & Marshall College7, University of Virginia8, University of British Columbia9, Lafayette College10, National Radio Astronomy Observatory11, Hillsdale College12, Norwich University13, McGill University14, University of Illinois at Urbana–Champaign15, The University of Texas Rio Grande Valley16, Columbia University17, University of Wisconsin–Milwaukee18, California Institute of Technology19, Haverford College20, First Green Bank21, United States Naval Research Laboratory22, Oberlin College23, Chinese Academy of Sciences24
TL;DR: In this article, the authors presented high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves.
Abstract: We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, and six high-timing-precision pulsars were observed weekly. All were observed at widely separated frequencies at each observing epoch in order to fit for time-variable dispersion delays. We describe our methods for data processing, time-of-arrival (TOA) calculation, and the implementation of a new, automated method for removing outlier TOAs. We fit a timing model for each pulsar that includes spin, astrometric, and (for binary pulsars) orbital parameters; time-variable dispersion delays; and parameters that quantify pulse-profile evolution with frequency. The timing solutions provide three new parallax measurements, two new Shapiro delay measurements, and two new measurements of significant orbital-period variations. We fit models that characterize sources of noise for each pulsar. We find that 11 pulsars show significant red noise, with generally smaller spectral indices than typically measured for non-recycled pulsars, possibly suggesting a different origin. A companion paper uses these data to constrain the strength of the gravitational-wave background.
481 citations
Search for extraterrestrial intelligence1, Ames Research Center2, Space Telescope Science Institute3, California Institute of Technology4, Massachusetts Institute of Technology5, Bishop's University6, Harvard University7, Space Science Institute8, University of Texas at Austin9, Villanova University10, Princeton University11, Goddard Space Flight Center12, University of Birmingham13, Aarhus University14, Principia College15, Lowell Observatory16, University of California, Berkeley17, Brigham Young University18, University of Nevada, Las Vegas19, San Diego State University20, Pennsylvania State University21
TL;DR: The Robovetter and the metrics it uses to decide which TCEs are called planet candidates in the DR25 KOI catalog are discussed and a value called the disposition score is discussed which provides an easy way to select a more reliable, albeit less complete, sample of candidates.
Abstract: We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4 yr of Kepler time series photometry (Data Release 25, Q1–Q17). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discuss the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK-dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable. The KOI catalog, the transit fits, and all of the simulated data used to characterize this catalog are available at the NASA Exoplanet Archive.
356 citations
TL;DR: In this paper, a new grid of presupernova models of massive stars extending in mass between 13 and 120 Msun, covering four metallicities (Fe/H]=0, -1, -2 and -3) and three initial rotation velocities (i.e. 0, 150 and 300 km/s).
Abstract: We present a new grid of presupernova models of massive stars extending in mass between 13 and 120 Msun, covering four metallicities (i.e. [Fe/H]=0, -1, -2 and -3) and three initial rotation velocities (i.e. 0, 150 and 300 km/s). The explosion has been simulated following three different assumptions in order to show how the yields depend on the remnant mass - initial mass relation. An extended network from H to Bi is fully coupled to the physical evolution of the models. The main results can be summarized as follows. a) At solar metallicity the maximum mass exploding as Red Super Giant (RSG) is of the order of 17 Msun in the non rotating case, all the more massive stars exploding as WR stars. All rotating models, vice versa, explode as Wolf-Rayet (WR) stars. b) The interplay between the core He burning and the H burning shell, triggered by the rotation induced instabilities, drives the synthesis of a large primary amount of all the products of the CNO, not just N14. A fraction of them enriches enormously the radiative part of the He core (and is responsible of the large production of F) and a fraction enters the convective core leading therefore to an important primary neutron flux able to synthesize heavy nuclei up to Pb. c) In our scenario, remnant masses of the order of those inferred by the first detections of the gravitational waves (GW150914, GW151226, GW170104, GW170814) are predicted at all metallicities for none or moderate initial rotation velocities.
328 citations
TL;DR: In this article, the authors present estimates of how many exoplanets the Transiting Exoplanet Survey Satellite (TESS) will detect, the physical properties of the detected planets, and the properties of those planets that those planets orbit.
Abstract: The Transiting Exoplanet Survey Satellite (TESS) has a goal of detecting small planets orbiting stars bright enough for mass determination via ground-based radial velocity observations. Here, we present estimates of how many exoplanets the TESS mission will detect, the physical properties of the detected planets, and the properties of the stars that those planets orbit. This work uses stars drawn from the TESS Input Catalog Candidate Target List and revises yields from prior studies that were based on Galactic models. We modeled the TESS observing strategy to select approximately 200,000 stars at 2-minute cadence, while the remaining stars are observed at 30-minute cadence in full-frame image data. We placed zero or more planets in orbit around each star, with physical properties following measured exoplanet occurrence rates, and used the TESS noise model to predict the derived properties of the detected exoplanets. In the TESS 2-minute cadence mode we estimate that TESS will find 1250 ± 70 exoplanets (90% confidence), including 250 smaller than 2 R(sub ⊕). Furthermore, we predict that an additional 3100 planets will be found in full-frame image data orbiting bright dwarf stars and more than 10,000 around fainter stars. We predict that TESS will find 500 planets orbiting M dwarfs, but the majority of planets will orbit stars larger than the Sun. Our simulated sample of planets contains hundreds of small planets amenable to radial velocity follow-up, potentially more than tripling the number of planets smaller than 4 R(sub ⊕) with mass measurements. This sample of simulated planets is available for use in planning follow-up observations and analyses.
290 citations
TL;DR: A detailed summary of the first detection of each molecular species, including the observational facility, wavelength range, transitions, and enabling laboratory spectroscopic work, as well as listing tentative and disputed detections are provided in this paper.
Abstract: To date, 204 individual molecular species, comprised of 16 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. These molecules range in size from two atoms to seventy, and have been detected across the electromagnetic spectrum from cm-wavelengths to the ultraviolet. This census presents a summary of the first detection of each molecular species, including the observational facility, wavelength range, transitions, and enabling laboratory spectroscopic work, as well as listing tentative and disputed detections. Tables of molecules detected in interstellar ices, external galaxies, protoplanetary disks, and exoplanetary atmospheres are provided. A number of visual representations of this aggregate data are presented and briefly discussed in context.
258 citations
TL;DR: Colossus as discussed by the authors is a Python package for calculations related to cosmology, the large-scale structure (LSS) of matter in the universe, and the properties of dark matter halos.
Abstract: This paper introduces Colossus, a public, open-source python package for calculations related to cosmology, the large-scale structure (LSS) of matter in the universe, and the properties of dark matter halos. The code is designed to be fast and easy to use, with a coherent, well-documented user interface. The cosmology module implements Friedman–Lemaitre–Robertson–Walker cosmologies including curvature, relativistic species, and different dark energy equations of state, and provides fast computations of the linear matter power spectrum, variance, and correlation function. The LSS module is concerned with the properties of peaks in Gaussian random fields and halos in a statistical sense, including their peak height, peak curvature, halo bias, and mass function. The halo module deals with spherical overdensity radii and masses, density profiles, concentration, and the splashback radius. To facilitate the rapid exploration of these quantities, Colossus implements more than 40 different fitting functions from the literature. I discuss the core routines in detail, with particular emphasis on their accuracy. Colossus is available at bitbucket.org/bdiemer/colossus.
245 citations
National Center for Supercomputing Applications1, University of Illinois at Urbana–Champaign2, Stanford University3, Fermilab4, SLAC National Accelerator Laboratory5, Brookhaven National Laboratory6, Institut d'Astrophysique de Paris7, University of Pennsylvania8, IFAE9, University College London10, ETH Zurich11, Max Planck Society12, Austin Peay State University13, Rhodes University14, New York University15, Texas A&M University16, Indian Institute of Technology, Hyderabad17, Ludwig Maximilian University of Munich18, Ohio State University19, Autonomous University of Madrid20, University of Michigan21, University of Cambridge22, University of Washington23, Santa Cruz Institute for Particle Physics24, Australian Astronomical Observatory25, Argonne National Laboratory26, University of São Paulo27, Catalan Institution for Research and Advanced Studies28, Institut de Ciències de l'Espai29, University of Southampton30, State University of Campinas31, Princeton University32, California Institute of Technology33, University of Sussex34, Oak Ridge National Laboratory35
TL;DR: The Dark Energy Survey (DES) photometric data set Y3 GOLD as discussed by the authors contains nearly 5000 deg2 of grizY imaging in the south Galactic cap including nearly 390 million objects, with depth reaching a signal-to-noise ratio ∼10 for extended objects up to i AB ∼ 23.0, and top-of-the-atmosphere photometric uniformity 98% and purity >99% for galaxies with 19 < i AB < 22.5.
Abstract: We describe the Dark Energy Survey (DES) photometric data set assembled from the first three years of science operations to support DES Year 3 cosmologic analyses, and provide usage notes aimed at the broad astrophysics community. Y3 GOLD improves on previous releases from DES, Y1 GOLD, and Data Release 1 (DES DR1), presenting an expanded and curated data set that incorporates algorithmic developments in image detrending and processing, photometric calibration, and object classification. Y3 GOLD comprises nearly 5000 deg2 of grizY imaging in the south Galactic cap, including nearly 390 million objects, with depth reaching a signal-to-noise ratio ∼10 for extended objects up to i AB ∼ 23.0, and top-of-the-atmosphere photometric uniformity 98% and purity >99% for galaxies with 19 < i AB < 22.5. Additionally, it includes per-object quality information, and accompanying maps of the footprint coverage, masked regions, imaging depth, survey conditions, and astrophysical foregrounds that are used to select the cosmologic analysis samples.
TL;DR: JWST/NIRCam [NAS5-02015], NASA/SAO ADS; NASA/IPAC Infrared Science Archive, Simbad; Mikulski Archive for Space Telescopes; European Community's Seventh Framework Programne (FP7 2012) [313188]
Abstract: JWST/NIRCam [NAS5-02015]; NASA/SAO ADS; NASA/IPAC Infrared Science Archive, Simbad; Mikulski Archive for Space Telescopes; European Community's Seventh Framework Programne (FP7 2012) [313188]
Ohio State University1, Aarhus University2, University of Birmingham3, Autonomous University of Barcelona4, University of New South Wales5, Spanish National Research Council6, University of La Laguna7, Space Science Institute8, Paris Diderot University9, University of Paris10, Max Planck Society11, University of Vienna12, Eötvös Loránd University13, Pierre-and-Marie-Curie University14, Vanderbilt University15, Ewha Womans University16, Yale University17, University of Arizona18, New Mexico State University19, Lund University20, University of Texas at Austin21, University of Washington22, University of Colorado Boulder23, University of Notre Dame24, University of Atacama25, University of Concepción26, University of Burgundy27, Texas Christian University28, Pennsylvania State University29, University of Antofagasta30
TL;DR: In this article, a catalog of stellar properties for a large sample of 6676 evolved stars with Apache Point Observatory Galactic Evolution Experiment spectroscopic parameters and Kepler asteroseismic data analyzed using five independent techniques.
Abstract: We present a catalog of stellar properties for a large sample of 6676 evolved stars with Apache Point Observatory Galactic Evolution Experiment spectroscopic parameters and Kepler asteroseismic data analyzed using five independent techniques. Our data include evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed by accounting for differences in their solar reference values. We include theoretically motivated corrections to the large frequency spacing (Δν) scaling relation, and we calibrate the zero-point of the frequency of the maximum power (ν max) relation to be consistent with masses and radii for members of star clusters. For most targets, the parameters returned by different pipelines are in much better agreement than would be expected from the pipeline-predicted random errors, but 22% of them had at least one method not return a result and a much larger measurement dispersion. This supports the usage of multiple analysis techniques for asteroseismic stellar population studies. The measured dispersion in mass estimates for fundamental calibrators is consistent with our error model, which yields median random and systematic mass uncertainties for RGB stars of order 4%. Median random and systematic mass uncertainties are at the 9% and 8% level, respectively, for red clump stars. (Less)
TL;DR: In this article, the authors systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission long-cadence data.
Abstract: The Kepler mission has provided exquisite data to perform an ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission long-cadence data. We produced a homogeneous catalog of the frequency of maximum power (typical uncertainty $\\sigma_{\
u_{\\rm max}}$=1.6\\%), the mean large frequency separation ($\\sigma_{\\Delta\
u}$=0.6\\%), oscillation amplitude ($\\sigma_{\\rm A}$=4.7\\%), granulation power ($\\sigma_{\\rm gran}$=8.6\\%), power excess width ($\\sigma_{\\rm width}$=8.8\\%), seismically-derived stellar mass ($\\sigma_{\\rm M}$=7.8\\%), radius ($\\sigma_{\\rm R}$=2.9\\%), and thus surface gravity ($\\sigma_{\\log g}$=0.01 dex). Thanks to the large red giant sample, we confirm that red-giant-branch (RGB) and helium-core-burning (HeB) stars collectively differ in the distribution of oscillation amplitude, granulation power, and width of power excess, which is mainly due to the mass difference. The distribution of oscillation amplitudes shows an extremely sharp upper edge at fixed $\
u_{\\rm max}$, which might hold clues to understand the excitation and damping mechanisms of the oscillation modes. We find both oscillation amplitude and granulation power depend on metallicity, causing a spread of 15\\% in oscillation amplitudes and a spread of 25\\% in granulation power from [Fe/H]=-0.7 to 0.5 dex. Our asteroseismic stellar properties can be used as reliable distance indicators and age proxies for mapping and dating galactic stellar populations observed by Kepler. They will also provide an excellent opportunity to test asteroseismology using Gaia parallaxes, and lift degeneracies in deriving atmospheric parameters in large spectroscopic surveys such as APOGEE and LAMOST.
University of KwaZulu-Natal1, Pennsylvania State University2, Princeton University3, Leiden University4, York University5, University of Toronto6, Johns Hopkins University7, Goddard Space Flight Center8, University of Michigan9, University of Pennsylvania10, Pontifical Catholic University of Chile11, Cornell University12, University of Arizona13, Sapienza University of Rome14, National Institute of Standards and Technology15, Florida State University16, Rutgers University17, University of Pittsburgh18, University of Oxford19, Yale University20, University of Tokyo21, Institute for the Physics and Mathematics of the Universe22, Haverford College23, Carnegie Mellon University24
TL;DR: In this paper, the authors presented the results of the first phase of the CONICYT FONDECYT-CFI under Compute Canada (CFI-CPF) project.
Abstract: U.S. National Science Foundation [AST-1440226, AST-0965625, AST-0408698]; Princeton University; University of Pennsylvania; Canada Foundation for Innovation (CFI); Comision Nacional de Investigacion Cientifica y Tecnologica de Chile (CONICYT); CFI under Compute Canada; Government of Ontario; Ontario Research Fund-Research Excellence; University of Toronto; NASA [NNX13AE56G, NNX14AB58G, NNX14AF73G, ATP NNX14AB57G]; National Research Foundation; South African Square Kilometre Array project; University of KwaZulu-Natal; Lyman Spitzer Jr. Fellowship; NSF [AST-1615657, AST-1312991, AST-1312380]; ERC [259505, 267117]; Labex ILP part of the Idex SUPER [ANR-10-LABX-63]; DOE [DE-SC0011114]; NASA Space Technology Research Fellowships; CONICYT [FONDECYT 1141113, Anillo ACT-1417, QUIMAL 160009, BASAL PFB-06 CATA]; CONICYT FONDECYT [3170846]; Jet Propulsion Laboratory, California Institute of Technology; National Aeronautics and Space Administration; Mishrahi Fund; Wilkinson Fund; Rutgers University; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science; FIRST program from the Japanese Cabinet Office; Ministry of Education, Culture, Sports, Science and Technology (MEXT); Japan Society for the Promotion of Science (JSPS); Japan Science and Technology Agency (JST); Toray Science Foundation; NAOJ; Kavli IPMU; KEK; ASIAA; National Aeronautics and Space Administration [NNX08AR22G]; National Science Foundation [AST-1238877]; ESO Very Large Telescope, under the "Large Programme" [182.A-0886]; [PHY-1214379]; [PHY-0855887]; [ANR-11-IDEX-0004-02]
TL;DR: The Modular Open Source Fitter for Transients (MOSFiT) as mentioned in this paper is a Python-based package that generates Monte Carlo ensembles of semi-analytical light-curve fits to those data sets and their associated Bayesian parameter posteriors.
Abstract: Much of the progress made in time-domain astronomy is accomplished by relating observational multiwavelength time-series data to models derived from our understanding of physical laws. This goal is typically accomplished by dividing the task in two: collecting data (observing), and constructing models to represent that data (theorizing). Owing to the natural tendency for specialization, a disconnect can develop between the best available theories and the best available data, potentially delaying advances in our understanding new classes of transients. We introduce MOSFiT: the Modular Open Source Fitter for Transients, a Python-based package that downloads transient data sets from open online catalogs (e.g., the Open Supernova Catalog), generates Monte Carlo ensembles of semi-analytical light-curve fits to those data sets and their associated Bayesian parameter posteriors, and optionally delivers the fitting results back to those same catalogs to make them available to the rest of the community. MOSFiT is designed to help bridge the gap between observations and theory in time-domain astronomy; in addition to making the application of existing models and creation of new models as simple as possible, MOSFiT yields statistically robust predictions for transient characteristics, with a standard output format that includes all the setup information necessary to reproduce a given result. As large-scale surveys such as that conducted with the Large Synoptic Survey Telescope (LSST), discover entirely new classes of transients, tools such as MOSFiT will be critical for enabling rapid comparison of models against data in statistically consistent, reproducible, and scientifically beneficial ways.
TL;DR: In this article, the authors present a comprehensive evolutionary model of the Sun's protoplanetary disk, constructed to resolve the CAI storage problem of meteoritics, and predict the abundances of calcium-rich, aluminum-rich inclusions (CAIs) and refractory lithophile elements under the central assumption that Jupiter's $\sim 30 \, M_{\oplus}$ core forms at about 3 AU at around 0.6 Myr and opened a gap CAIs are trapped in the pressure maximum beyond Jupiter; carbonaceous chondrites formed there.
Abstract: We present a comprehensive evolutionary model of the Sun's protoplanetary disk, constructed to resolve the "CAI Storage" problem of meteoritics. We predict the abundances of calcium-rich, aluminum-rich inclusions (CAIs) and refractory lithophile elements under the central assumption that Jupiter's $\sim 30 \, M_{\oplus}$ core forms at about 3 AU at around 0.6 Myr and opened a gap CAIs are trapped in the pressure maximum beyond Jupiter; carbonaceous chondrites formed there. Inside Jupiter's orbit, CAIs were depleted by aerodynamic drag; ordinary and enstatite chondrites formed there. For 16 chondrites and achondrites, we review meteoritic data on their CAI and refractory abundances and their times of formation, constrained by radiometric dating and thermal models. We predict their formation locations, finding excellent consistency with other location information (water content, asteroid spectra and parent bodies). We predict the size of particle concentrated by turbulence for each chondrite, finding excellent matches to each chondrites's mean chondrule diameter. These consistencies imply meteorite parent bodies assembled quickly from local materials concentrated by turbulence, and usually did not migrate far. We predict CI chondrites are depleted in refractory lithophile elements relative to the Sun, by about 12% (0.06 dex). We constrain the variation of turbulence parameter $\alpha$ in the disk, and find a limited role for magnetorotational instability, favoring hydrodynamical instabilities in the outer disk, plus magnetic disk winds in the inner disk. Between 3 and 4 Myr at least, gas persisted outside Jupiter but was depleted inside it, and the solar nebula was a transition disk.
Clemson University1, Istituto Nazionale di Fisica Nucleare2, University of Trieste3, University of Padua4, Instituto Politécnico Nacional5, SLAC National Accelerator Laboratory6, University of Turin7, Goddard Space Flight Center8, INAF9, Harvard University10, United States Naval Research Laboratory11, Agenzia Spaziale Italiana12, University of Bologna13, Hiroshima University14, University of Erlangen-Nuremberg15, University of Maryland, College Park16, George Washington University17, University of North Florida18, Royal Institute of Technology19, University of Iceland20, Stockholm University21, University of Denver22, Max Planck Society23, University of Johannesburg24, Purdue University25, Nagoya University26, Catalan Institution for Research and Advanced Studies27, University of Perugia28, California State University, Los Angeles29, University of Nova Gorica30
TL;DR: In this paper, a search for spatial extension in high-latitude sources in recent Fermi point source catalogs is presented, which provides source extensions and likelihood profiles for a suite of tested source morphologies.
Abstract: We present a search for spatial extension in high-latitude () sources in recent Fermi point source catalogs. The result is the Fermi High-Latitude Extended Sources Catalog, which provides source extensions (or upper limits thereof) and likelihood profiles for a suite of tested source morphologies. We find 24 extended sources, 19 of which were not previously characterized as extended. These include sources that are potentially associated with supernova remnants and star-forming regions. We also found extended γ-ray emission in the vicinity of the Cen A radio lobes and—at GeV energies for the first time—spatially coincident with the radio emission of the SNR CTA 1, as well as from the Crab Nebula. We also searched for halos around active galactic nuclei, which are predicted from electromagnetic cascades induced by the e + e − pairs that are deflected in intergalactic magnetic fields. These pairs are produced when γ-rays interact with background radiation fields. We do not find evidence for extension in individual sources or in stacked source samples. This enables us to place limits on the flux of the extended source components, which are then used to constrain the intergalactic magnetic field to be stronger than 3 × 10−16 G for a coherence length λ ≳ 10 kpc, even when conservative assumptions on the source duty cycle are made. This improves previous limits by several orders of magnitude.
TL;DR: MPI-AMRVAC as discussed by the authors is an open-source framework for parallel, grid-adaptive simulations of hydrodynamic and magnetohydrodynamic (MHD) applications.
Abstract: We report on the development of MPI-AMRVAC version 2.0, which is an open-source framework for parallel, grid-adaptive simulations of hydrodynamic and magnetohydrodynamic (MHD) astrophysical applications. The framework now supports radial grid stretching in combination with adaptive mesh refinement (AMR). The advantages of this combined approach are demonstrated with one-dimensional, two-dimensional and three-dimensional examples of spherically symmetric Bondi accretion, steady planar Bondi-Hoyle-Lyttleton flows, and wind accretion in Supergiant X-ray binaries. Another improvement is support for the generic splitting of any background magnetic field. We present several tests relevant for solar physics applications to demonstrate the advantages of field splitting on accuracy and robustness in extremely low plasma $\beta$ environments: a static magnetic flux rope, a magnetic null-point, and magnetic reconnection in a current sheet with either uniform or anomalous resistivity. Our implementation for treating anisotropic thermal conduction in multi-dimensional MHD applications is also described, which generalizes the original slope limited symmetric scheme from 2D to 3D. We perform ring diffusion tests that demonstrate its accuracy and robustness, and show that it prevents the unphysical thermal flux present in traditional schemes. The improved parallel scaling of the code is demonstrated with 3D AMR simulations of solar coronal rain, which show satisfactory strong scaling up to 2000 cores. Other framework improvements are also reported: the modernization and reorganization into a library, the handling of automatic regression tests, the use of inline/online Doxygen documentation, and a new future-proof data format for input/output
Queen's University Belfast1, National Research Council2, University of Victoria3, University of British Columbia4, Centre national de la recherche scientifique5, University of Arizona6, Academia Sinica Institute of Astronomy and Astrophysics7, Planetary Science Institute8, Pennsylvania State University9, University of Helsinki10, Las Cumbres Observatory Global Telescope Network11, National Central University12, Macau University of Science and Technology13, Slovak Academy of Sciences14, University of Washington15, University of Oklahoma16, University of Pennsylvania17, Harvard University18, University of Michigan19, Kindai University20, University of California, Santa Cruz21, Lowell Observatory22
TL;DR: The Outer Solar System Origins Survey (OSSOS) as discussed by the authors was used to detect 838 trans-Neptunian objects (TNOs) with accurate known orbits, including 313 resonant TNOs and 132 plutinos.
Abstract: The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program
in 2013-2017 with the Canada-France-Hawaii Telescope, surveyed 155 deg$^{2}$ of
sky to depths of $m_r = 24.1$-25.2. We present 838 outer Solar System
discoveries that are entirely free of ephemeris bias. This increases the
inventory of trans-Neptunian objects (TNOs) with accurately known orbits by
nearly 50%. Each minor planet has 20-60 Gaia/Pan-STARRS-calibrated astrometric
measurements made over 2-5 oppositions, which allows accurate classification of
their orbits within the trans-Neptunian dynamical populations. The populations
orbiting in mean-motion resonance with Neptune are key to understanding
Neptune's early migration. Our 313 resonant TNOs, including 132 plutinos,
triple the available characterized sample and include new occupancy of distant
resonances out to semi-major axis $a \sim 130$ au. OSSOS doubles the known
population of the non-resonant Kuiper belt, providing 436 TNOs in this region,
all with exceptionally high-quality orbits of $a$ uncertainty $\sigma_{a} \leq
0.1\%$; they show the belt exists from $a \gtrsim 37$ au, with a lower
perihelion bound of $35$ au. We confirm the presence of a concentrated
low-inclination $a\simeq 44$ au "kernel" population and a dynamically cold
population extending beyond the 2:1 resonance. We finely quantify the survey's
observational biases. Our survey simulator provides a straightforward way to
impose these biases on models of the trans-Neptunian orbit distributions,
allowing statistical comparison to the discoveries. The OSSOS TNOs,
unprecedented in their orbital precision for the size of the sample, are ideal
for testing concepts of the history of giant planet migration in the Solar
System.
TL;DR: In this paper, the authors give a brief overview of the most basic MCMC method and some practical advice for the use of MCMC in real inference problems, giving advice on method choice, tuning for performance, methods for initialization, tests of convergence, troubleshooting, and use of the chain output to produce or report parameter estimates with associated uncertainties.
Abstract: Markov Chain Monte Carlo (MCMC) methods for sampling probability density functions (combined with abundant computational resources) have transformed the sciences, especially in performing probabilistic inferences, or fitting models to data. In this primarily pedagogical contribution, we give a brief overview of the most basic MCMC method and some practical advice for the use of MCMC in real inference problems. We give advice on method choice, tuning for performance, methods for initialization, tests of convergence, troubleshooting, and use of the chain output to produce or report parameter estimates with associated uncertainties. We argue that autocorrelation time is the most important test for convergence, as it directly connects to the uncertainty on the sampling estimate of any quantity of interest. We emphasize that sampling is a method for doing integrals; this guides our thinking about how MCMC output is best used.
TL;DR: The DECam Plane Survey as mentioned in this paper is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera at Cerro Tololo, which is designed to reach past the main-sequence turnoff of old populations at the distance of the Galactic center through a reddening E(B - V) of 1.5 mag.
Abstract: Author(s): Schlafly, EF; Green, GM; Lang, D; Daylan, T; Finkbeiner, DP; Lee, A; Meisner, AM; Schlegel, D; Valdes, F | Abstract: The DECam Plane Survey is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera at Cerro Tololo. The survey is designed to reach past the main-sequence turn-off of old populations at the distance of the Galactic center through a reddening E(B - V) of 1.5 mag. Typical singleexposure depths are 23.7, 22.8, 22.3, 21.9, and 21.0 mag (AB) in the grizY bands, with seeing around 1′. The footprint covers the Galactic plane with |b| ≲ 4°, 5° g l g -120°. The survey pipeline simultaneously solves for the positions and fluxes of tens of thousands of sources in each image, delivering positions and fluxes of roughly two billion stars with better than 10 mmag precision. Most of these objects are highly reddened and deep in the Galactic disk, probing the structure and properties of the Milky Way and its interstellar medium. The fullyprocessed images and derived catalogs are publicly available.
TL;DR: In this article, the authors presented the "SINS/zC-SINF AO survey" of 35 star-forming galaxies, the largest sample with deep adaptive optics (AO)-assisted near-infrared integral field spectroscopy at z similar to 2.5 kpc.
Abstract: We present the "SINS/zC-SINF AO survey" of 35 star-forming galaxies, the largest sample with deep adaptive optics (AO)-assisted near-infrared integral field spectroscopy at z similar to 2. The observations, taken with SINFONI at the Very Large Telescope, resolve the Ha and [N II] emission and kinematics on scales of similar to 1.5 kpc. The sample probes the massive (M star similar to 2 x 10(9) - 3 x 10(11) M-circle dot), actively star-forming (SFR similar to 10-600 M-circle dot yr(-1)) part of the z similar to 2 galaxy population over a wide range of colors ((U-V)(rest) similar to 0.15-1.5 mag) and half-light radii (R-e,(H) similar to 1-8.5 kpc). The sample overlaps largely with the "main sequence" of star-forming galaxies in the same redshift range to a similar K-AB = 23 mag limit;it has similar to 0.3 dex higher median specific SFR, similar to 0.1 mag bluer median (U - V)(rest) color, and similar to 10% larger median rest-optical size. We describe the observations, data reduction, and extraction of basic flux and kinematic properties. With typically 3-4 times higher resolution and 4-5 times longer integrations (up to 23 hr) than the seeing-limited data sets of the same objects, the AO data reveal much more detail in morphology and kinematics. The complete AO observations confirm the majority of kinematically classified disks and the typically elevated disk velocity dispersions previously reported based on subsets of the data. We derive typically flat or slightly negative radial [N II]/H alpha gradients, with no significant trend with global galaxy properties, kinematic nature, or the presence of an AGN. Azimuthal variations in [N II]/H alpha are seen in several sources and are associated with ionized gas outflows and possibly more metal-poor star-forming clumps or small companions.
TL;DR: The catalog of hierarchical stellar systems with three or more components is an update of the original 1997 version of the MSC as mentioned in this paper, which provides distances, component's masses and periods, as well as supplementary information (astrometry, photometry, identifiers, orbits, notes).
Abstract: The catalog of hierarchical stellar systems with three or more components is an update of the original 1997 version of the MSC. For two thousand hierarchies, the new MSC provides distances, component's masses and periods, as well as supplementary information (astrometry, photometry, identifiers, orbits, notes). The MSC content and format are explained, its incompleteness and strong observational selection are stressed. Nevertheless, the MSC can be used for statistical studies and it is a valuable source for planning observations of multiple stars. Rare classes of stellar hierarchies found in the MSC (with 6 or 7 components, extremely eccentric orbits, planar and possibly resonant orbits, hosting planets) are briefly presented. High-order hierarchies have smaller velocity dispersion compared to triples and are often associated with moving groups. The paper concludes by the analysis of the ratio of periods and separations between inner and outer subsystems. In wide hierarchies, the ratio of semimajor axes, estimated statistically, is distributed between 3 and 300, with no evidence of dynamically unstable systems.
TL;DR: In this article, a cross-calibrated catalog of Hipparcos and Gaia is presented to enable their use in measuring changes in proper motion, i.e., accelerations in the plane of the sky.
Abstract: This paper presents a cross-calibrated catalog of Hipparcos and Gaia astrometry to enable their use in measuring changes in proper motion, i.e., accelerations in the plane of the sky. The final catalog adopts the reference frame of the second Gaia data release (DR2) and locally cross-calibrates both the scaled Hipparcos-Gaia DR2 positional differences and the Hipparcos proper motions themselves to this frame. This gives three nearly independent proper motion measurements per star, with the scaled positional difference usually being the most precise. We find that a linear combination of the two Hipparcos reductions is superior to either reduction on its own, and address error inflation for both Hipparcos and Gaia DR2. Our adopted error inflation is additive (in quadrature) for Hipparcos and multiplicative for Gaia. We provide the covariance matrices along with the central epochs of all measurements. Our final proper motion differences are accurately Gaussian with the appropriate variances, and are suitable for acceleration measurements and orbit fitting. The catalog is constructed with an eye toward completeness; it contains nearly 98\% of the Hipparcos stars. It also includes a handful of spurious entries and a few stars with poor Hipparcos reductions that the user must vet by hand. Statistical distributions of accelerations derived from this catalog should be interpreted with caution.
TL;DR: In this paper, the authors describe the use of multiple scale factors, instead of the single scaling factor used previously, to align the theoretical harmonic frequencies with the experimental fundamentals, and the impact of these changes on the analysis of an astronomical spectrum through database-fitting is considered.
Abstract: Version 3.00 of the library of computed spectra in the NASA Ames PAH IR Spectroscopic Database (PAHdb) is described. Version 3.00 introduces the use of multiple scale factors, instead of the single scaling factor used previously, to align the theoretical harmonic frequencies with the experimental fundamentals. The use of multiple scale factors permits the use of a variety of basis sets; this allows new PAH species to be included in the database, such as those containing oxygen, and yields an improved treatment of strained species and those containing nitrogen. In addition, the computed spectra of 2439 new PAH species have been added. The impact of these changes on the analysis of an astronomical spectrum through database-fitting is considered and compared with a fit using Version 2.00 of the library of computed spectra. Finally, astronomical constraints are defined for the PAH spectral libraries in PAHdb.
Leiden University1, Adam Mickiewicz University in Poznań2, University of Oklahoma3, Nicolaus Copernicus University in Toruń4, National Radio Astronomy Observatory5, Harvard University6, State University of New York at Fredonia7, University of Illinois at Urbana–Champaign8, University of Arizona9, University of Virginia10, University of California, San Diego11, University of Chile12, Max Planck Society13
TL;DR: In this article, a C-band (4.1 cm and 6.4 cm) survey of all known protostars (Class 0 and Class I) in Perseus as part of the VLA Nascent Disk and Multiplicity (VANDAM) Survey is presented.
Abstract: Emission from protostars at centimeter radio wavelengths has been shown to trace the free-free emission arising from ionizing shocks as a result of jets and outflows driven by protostars. Therefore, measuring properties of protostars at radio frequencies can provide valuable insights into the nature of their outflows and jets. We present a C-band (4.1 cm and 6.4 cm) survey of all known protostars (Class 0 and Class I) in Perseus as part of the VLA Nascent Disk and Multiplicity (VANDAM) Survey. We examine the known correlations between radio flux density and protostellar parameters such as bolometric luminosity and outflow force, for our sample. We also investigate the relationship between radio flux density and far-infrared line luminosities from Herschel. We show that free-free emission originates most likely from J-type shocks; however, the large scatter indicates that those two types of emission probe different time and spatial scales. Using C-band fluxes, we removed an estimation of free-free contamination from the corresponding Ka-band (9 mm) flux densities that primarily probe dust emission from embedded disks. We find that the compact ($<$~1") dust emission is lower for Class I sources (median dust mass 96 M$_{\oplus}$) relative to Class 0 (248 M$_{\oplus}$), but several times higher than in Class II (5-15 M$_{\oplus}$). If this compact dust emission is tracing primarily the embedded disk, as is likely for many sources, this result provides evidence for decreasing disk masses with protostellar evolution, with sufficient mass for forming giant planet cores primarily at early times.
TL;DR: The JINAbase database as mentioned in this paper contains 1658 unique stars, 60% of which have [Fe/H] < 2.5. But the database is limited to a subset of stars with unique chemical element signatures (e.g., r-process stars, s-process and CEMP stars).
Abstract: Reconstructing the chemical evolution of the Milky Way is crucial for understanding the formation of stars, planets, and galaxies throughout cosmic time. Different studies associated with element production in the early universe and how elements are incorporated into gas and stars are necessary to piece together how the elements evolved. These include establishing chemical abundance trends, as set by metal-poor stars, comparing nucleosynthesis yield predictions with stellar abundance data, and theoretical modeling of chemical evolution. To aid these studies, we have collected chemical abundance measurements and other information such as stellar parameters, coordinates, magnitudes, and radial velocities, for extremely metal-poor stars from the literature. The database, JINAbase, contains 1658 unique stars, 60% of which have [Fe/H]<2.5. This information is stored in an SQL database, together with a user-friendly queryable web application (this http URL). Objects with unique chemical element signatures (e.g., r-process stars, s-process and CEMP stars) are labeled or can be classified as such. The web application enables fast selection of customized comparison samples from the literature for the aforementioned studies and many more. Using the multiple entries for three of the most well studied metal-poor stars, we evaluate systematic uncertainties of chemical abundances measurements. We provide a brief guide on the selection of chemical elements for model comparisons for non- spectroscopists who wish to learn about metal-poor stars and the details of chemical abundances measurements.
Ehime University1, University of Barcelona2, Graduate University for Advanced Studies3, Princeton University4, Subaru5, Tohoku University6, Seisa University7, National Tsing Hua University8, University of Tokyo9, Onomichi City University10, Institute for the Physics and Mathematics of the Universe11, Nagoya University12, Kyoto Sangyo University13, Hokkaido University14, Academia Sinica15, Kyoto University16, Stanford University17
TL;DR: Matsuoka et al. as discussed by the authors reported discovery of 41 new high-z quasars and luminous galaxies, which were spectroscopically identified at 5.7 ≤ z ≤ 6.9.
Abstract: We report discovery of 41 new high-z quasars and luminous galaxies, which were spectroscopically identified at 5.7 ≤ z ≤ 6.9. This is the fourth in a series of papers from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, based on the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. We selected the photometric candidates by a Bayesian probabilistic algorithm, and then Corresponding author: Yoshiki Matsuoka yk.matsuoka@cosmos.ehime-u.ac.jp