CLASSY III. The Properties of Starburst-driven Warm Ionized Outflows

Creators: Xu, Xinfeng; Heckman, Timothy; Henry, Alaina; Berg, Danielle A.; Chisholm, John; James, Bethan L.; Martin, Crystal L.; Stark, Daniel P.; Aloisi, Alessandra; Amorín, Ricardo O.; Arellano-Córdova, Karla Z.; Bordoloi, Rongmon; Charlot, Stéphane; Chen, Zuyi; Hayes, Matthew; Mingozzi, Matilde; Sugahara, Yuma; Kewley, Lisa J.; Ouchi, Masami; Scarlata, Claudia; Steidel, Charles C.

Abstract

We report the results of analyses of galactic outflows in a sample of 45 low-redshift starburst galaxies in the COS Legacy Archive Spectroscopic SurveY (CLASSY), augmented by five additional similar starbursts with Cosmic Origins Spectrograph (COS) data. The outflows are traced by blueshifted absorption lines of metals spanning a wide range of ionization potential. The high quality and broad spectral coverage of CLASSY data enable us to disentangle the absorption due to the static interstellar medium (ISM) from that due to outflows. We further use different line multiplets and doublets to determine the covering fraction, column density, and ionization state as a function of velocity for each outflow. We measure the outflow's mean velocity and velocity width, and find that both correlate in a highly significant way with the star formation rate, galaxy mass, and circular velocity over ranges of four orders of magnitude for the first two properties. We also estimate outflow rates of metals, mass, momentum, and kinetic energy. We find that, at most, only about 20% of silicon created and ejected by supernovae in the starburst is carried out in the warm phase we observe. The outflows' mass-loading factor increases steeply and inversely with both circular and outflow velocity (log–log slope ∼−1.6), and reaches ∼10 for dwarf galaxies. We find that the outflows typically carry about 10%–100% of the momentum injected by massive stars and about 1%–20% of the kinetic energy. We show that these results place interesting constraints on, and new insights into, models and simulations of galactic winds.

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 2022 February 7; revised 2022 April 19; accepted 2022 May 4; published 2022 July 15. 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 is grateful for the support of this program, HST-GO-15840, 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. thanks the European Space Agency (ESA) for its support. 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 research has made use of the HSLA database, developed and maintained at STScI, Baltimore, MD, USA. We also thank the anonymous referee for the insightful comments on the paper. Facilities: HST (COS) - , LBT (MODS) - , APO (SDSS) - , KECK (ESI) - , VLT (MUSE - , VIMOS) - . Software: astropy (Astropy Collaboration et al. 2018) BEAGLE (Chevallard & Charlot 2016), CalCOS (STScI), dustmaps (Green 2018), jupyter (Kluyver et al. 2016), MPFIT (Markwardt 2009), Photutils (Bradley et al. 2021), python (Van Rossum & Drake 2009), pysynphot (STScI Development Team 2013).

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