Year: 2022
Type: article
Abstract: The COS Legacy Archive Spectroscopic SurveY (CLASSY) is designed to provide the community with a spectral atlas of 45 nearby star-forming galaxies that were chosen to cover similar properties to those seen at high z (z > 6). The prime high-level science product of CLASSY is accurately coadded UV spectra, ranging from ∼1000 to 2000 Å, derived from a combination of archival and new data obtained with HST’s Cosmic Origins Spectrograph (COS). This paper details the multistage technical processes of creating this prime data product and the methodologies involved in extracting, reducing, aligning, and coadding far-ultraviolet and near-ultraviolet (NUV) spectra. We provide guidelines on how to successfully utilize COS observations of extended sources, despite COS being optimized for point sources, and best-practice recommendations for the coaddition of UV spectra in general. Moreover, we discuss the effects of our reduction and coaddition techniques in the scientific application of the CLASSY data. In particular, we find that accurately accounting for flux calibration offsets can affect the derived properties of the stellar populations, while customized extractions of NUV spectra for extended sources are essential for correctly diagnosing the metallicity of galaxies via C iii] nebular emission. Despite changes in spectral resolution of up to ∼25% between individual data sets (due to changes in the COS line-spread function), no adverse affects were observed on the difference in velocity width and outflow velocities of isolated absorption lines when measured in the final combined data products, owing in part to our signal-to-noise regime of S/N < 20.
Authors: Bethan L. James, Danielle A. Berg, Teagan King, David J. Sahnow, Matilde Mingozzi, John Chisholm, Timothy Heckman, Crystal L. Martin, Dan P. Stark, Alessandra Aloisi, Ricardo O. Amorín, Karla Z. Arellano-Córdova, Matthew Bayliss, Rongmon Bordoloi, Jarle Brinchmann, Stéphane Charlot, Zuyi Chen, Jacopo Chevallard, Ilyse Clark, Dawn K. Erb, Anna Feltre, Matthew Hayes, Alaina Henry, Svea Hernandez, Anne Jaskot, Lisa J. Kewley, Nimisha Kumari, Claus Leitherer, Mario Llerena, Michael Maseda, Themiya Nanayakkara, Masami Ouchi, Adele Plat, Richard W. Pogge, Swara Ravindranath, Jane R. Rigby, Claudia Scarlata, Peter Senchyna, Evan D. Skillman, Charles C. Steidel, Allison L. Strom, Yuma Sugahara, Stephen M. Wilkins, Aida Wofford, Xinfeng Xu, (The CLASSY Team)
Institutions: Space Telescope Science Institute, The University of Texas at Austin, Johns Hopkins University, University of California, Santa Barbara, University of Arizona, University of La Serena, University of Cincinnati, North Carolina State University, Universidade do Porto, Institute of Astrophysics and Space Sciences, Centro de Astrofísica da Universidade do Porto, Centre National de la Recherche Scientifique, Institut d'Astrophysique de Paris, Sorbonne Université, Université Pierre-et-Marie-Curie, University of Wisconsin–Milwaukee, Osservatorio di Astrofisica e Scienza dello Spazio, National Institute for Astrophysics, Stockholm University, AlbaNova, Williams College, Australian National University, ASTRO-3D, ARC Centre of Excellence for All-sky Astrophysics, Leiden University, Leiden Observatory, Swinburne University of Technology, Institute for Cosmic Ray Research, The University of Tokyo, The Ohio State University, Goddard Space Flight Center, University of Minnesota, Carnegie Observatories, California Institute of Technology, Carnegie Institution for Science, Waseda University, National Astronomical Observatory of Japan, Waseda Research Institute for Science and Engineering, University of Sussex, Universidad Nacional Autónoma de México
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Award: G58316358
OpenAlex ID: W4281753610