The COS Legacy Archive Spectroscopy SurveY (CLASSY) Treasury Atlas
Abstract
Far-ultraviolet (FUV; ~1200-2000 angstroms) 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 JWST 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 COS Legacy Spectroscopic SurveY (CLASSY) treasury and its first high level science product, the CLASSY atlas. CLASSY builds on the HST archive to construct the first high-quality (S/N_1500 >~ 5/resel), high-resolution (R~15,000) FUV spectral database of 45 nearby (0.002 < z < 0.182) star-forming galaxies. The CLASSY atlas, available to the public via the CLASSY website, is the result of optimally extracting and coadding 170 archival+new spectra from 312 orbits of HST observations. The CLASSY sample covers a broad range of properties including stellar mass (6.2 < logM_star(M_sol) < 10.1), star formation rate (-2.0 < log SFR (M_sol/yr) < +1.6), direct gas-phase metallicity (7.0 < 12+log(O/H) < 8.8), ionization (0.5 < O_32 < 38.0), reddening (0.02 < E(B-V < 0.67), and nebular density (10 < n_e (cm^-3) < 1120). CLASSY is biased to UV-bright star-forming galaxies, resulting in a sample that is consistent with z~0 mass-metallicity relationship, but is offset to higher SFRs 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.
Keywords
Cite
@article{arxiv.2203.07357,
title = {The COS Legacy Archive Spectroscopy SurveY (CLASSY) Treasury Atlas},
author = {Danielle A. Berg and Bethan L. James and Teagan King and Meaghan Mcdonald and Zuyi Chen and John Chisholm and Timothy Heckman and Crystal L. Martin and Dan P. Stark and The Classy Team and : and Alessandra Aloisi and Ricardo O. AmorÍn and Karla Z. Arellano-CÓrdova and Matthew Bayliss and Rongmon Bordoloi and Jarle Brinchmann and StÉphane Charlot and Jacopo Chevallard and Ilyse Clark and Dawn K. Erb and Anna Feltre and Matthew Hayes and Alaina Henry and Svea Hernandez and Anne Jaskot and Tucker Jones and Lisa J. Kewley and Nimisha Kumari and Claus Leitherer and Mario Llerena and Michael Maseda and Matilde Mingozzi and Themiya Nanayakkara and Masami Ouchi and Adele Plat and Richard W. Pogge and Swara Ravindranath and Jane R. Rigby and Ryan Sanders and Claudia Scarlata and Peter Senchyna and Evan D. Skillman and Charles C. Steidel and Allison L. Strom and Yuma Sugahara and Stephen M. Wilkins and Aida Wofford and Xinfeng Xu},
journal= {arXiv preprint arXiv:2203.07357},
year = {2022}
}
Comments
Accepted for publication in ApJ