The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas

Creators: Berg, Danielle A.; James, Bethan L.; King, Teagan; McDonald, Meaghan; Chen, Zuyi; Chisholm, John; Heckman, Timothy; Martin, Crystal L.; Stark, Dan P.; Aloisi, Alessandra; Amorín, Ricardo O.; Arellano-Córdova, Karla Z.; Bayliss, Matthew; Bordoloi, Rongmon; Brinchmann, Jarle; Charlot, Stéphane; Chevallard, Jacopo; Clark, Ilyse; Erb, Dawn K.; Feltre, Anna; Gronke, Max; Hayes, Matthew; Henry, Alaina; Hernandez, Svea; Jaskot, Anne; Jones, Tucker; Kewley, Lisa J.; Kumari, Nimisha; Leitherer, Claus; Llerena, Mario; Maseda, Michael; Mingozzi, Matilde; Nanayakkara, Themiya; Ouchi, Masami; Plat, Adele; Pogge, Richard W.; Ravindranath, Swara; Rigby, Jane R.; Sanders, Ryan; Scarlata, Claudia; Senchyna, Peter; Skillman, Evan D.; Steidel, Charles C.; Strom, Allison L.; Sugahara, Yuma; Wilkins, Stephen M.; Wofford, Aida; Xu, Xinfeng; CLASSY Team

Abstract

Far-ultraviolet (FUV; ∼1200–2000 Å) spectra are fundamental to our understanding of star-forming galaxies, providing a unique window on massive stellar populations, chemical evolution, feedback processes, and reionization. The launch of the James Webb Space Telescope will soon usher in a new era, pushing the UV spectroscopic frontier to higher redshifts than ever before; however, its success hinges on a comprehensive understanding of the massive star populations and gas conditions that power the observed UV spectral features. This requires a level of detail that is only possible with a combination of ample wavelength coverage, signal-to-noise, spectral-resolution, and sample diversity that has not yet been achieved by any FUV spectral database. We present the Cosmic Origins Spectrograph Legacy Spectroscopic Survey (CLASSY) treasury and its first high-level science product, the CLASSY atlas. CLASSY builds on the Hubble Space Telescope (HST) archive to construct the first high-quality (S/N_(1500 Å) ≳ 5/resel), high-resolution (R ∼ 15,000) FUV spectral database of 45 nearby (0.002 z M_⋆(M_⊙)) M_⊙ yr⁻¹) < +1.6), direct gas-phase metallicity (7.0 < 12 + log(O/H) < 8.8), ionization (0.5 < O₃₂ < 38.0), reddening (0.02 < E(B − V) < 0.67), and nebular density (10 < nₑ (cm⁻³) < 1120). CLASSY is biased to UV-bright star-forming galaxies, resulting in a sample that is consistent with the z ∼ 0 mass–metallicity relationship, but is offset to higher star formation rates by roughly 2 dex, similar to z ≳ 2 galaxies. This unique set of properties makes the CLASSY atlas the benchmark training set for star-forming galaxies across cosmic time.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 October 3; revised 2022 February 16; accepted 2022 February 17; published 2022 July 27. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive 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 CLASSY team thanks the referee for thoughtful feedback that significantly improved both the paper and the HLSPs. D.A.B. is grateful for the support for this program, HST-GO-15840, that was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Associations of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. B.L.J. is grateful for support from the European Space Agency (ESA). The CLASSY collaboration extends special gratitude to the Lorentz Center for useful discussions during the "Characterizing Galaxies with Spectroscopy with a view for JWST" 2017 workshop that led to the formation of the CLASSY collaboration and survey. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III website is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. This work also uses the services of the ESO Science Archive Facility, observations collected at the European Southern Observatory under ESO programmes 096.B-0690, 0103.B-0531, 0103.D-0705, and 0104.D-0503, and observations obtained with the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are as follows: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, University of Notre Dame, University of Minnesota, and University of Virginia. This paper made use of the modsIDL spectral data reduction pipeline developed in part with funds provided by NSF grant AST-1108693 and a generous gift from OSU Astronomy alumnus David G. Price through the Price Fellowship in Astronomical Instrumentation. This research has made use of the HSLA database, developed and maintained at STScI, Baltimore, USA. Facilities: HST (COS) - , LBT (MODS) - , Astrophysical Observatory of the Smithsonian Institution (APO;SDSS) - , KECK (ESI) - , Very Large Telescope (MUSE - , VIMOS). - Software: astropy (The Astropy Collaboration 2013, 2018); BEAGLE (Chevallard & Charlot 2016); CalCOS (STScI); dustmaps (Green 2018); jupyter (Kluyver et al. 2016); LINMIX (Kelly 2007); MPFIT (Markwardt 2009); MODS reduction Pipeline, Photutils (Bradley et al. 2021); PYNEB (Luridiana et al. 2012, 2015); python, pysynphot (STScI Development Team et al. 2013); RASCAS (Michel-Dansac et al. 2020); SALT (Scarlata & Panagia 2015); STARLIGHT (Fernandes 2005); tlac (Gronke & Dijkstra 2014); XIDL.

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