The Low-redshift Lyman Continuum Survey. II. New Insights into LyC Diagnostics

Creators: Flury, Sophia R.; Jaskot, Anne E.; Ferguson, Harry C.; Worseck, Gábor; Makan, Kirill; Chisholm, John; Saldana-Lopez, Alberto; Schaerer, Daniel; McCandliss, Stephan R.; Xu, Xinfeng; Wang, Bingjie; Oey, M. S.; Ford, N. M.; Heckman, Timothy; Ji, Zhiyuan; Giavalisco, Mauro; Amorín, Ricardo; Atek, Hakim; Blaizot, Jeremy; Borthakur, Sanchayeeta; Carr, Cody; Castellano, Marco; De Barros, Stephane; Dickinson, Mark; Finkelstein, Steven L.; Fleming, Brian; Fontanot, Fabio; Garel, Thibault; Grazian, Andrea; Hayes, Matthew; Henry, Alaina; Mauerhofer, Valentin; Micheva, Genoveva; Ostlin, Goran; Papovich, Casey; Pentericci, Laura; Ravindranath, Swara; Rosdahl, Joakim; Rutkowski, Michael; Santini, Paola; Scarlata, Claudia; Teplitz, Harry; Thuan, Trinh; Trebitsch, Maxime; Vanzella, Eros; Verhamme, Anne

Abstract

The Lyman continuum (LyC) cannot be observed at the epoch of reionization (z ≳ 6) owing to intergalactic H i absorption. To identify LyC emitters (LCEs) and infer the fraction of escaping LyC, astronomers have developed various indirect diagnostics of LyC escape. Using measurements of the LyC from the Low-redshift Lyman Continuum Survey (LzLCS), we present the first statistical test of these diagnostics. While optical depth indicators based on Lyα, such as peak velocity separation and equivalent width, perform well, we also find that other diagnostics, such as the [O iii]/[O ii] flux ratio and star formation rate surface density, predict whether a galaxy is an LCE. The relationship between these galaxy properties and the fraction of escaping LyC flux suggests that LyC escape depends strongly on H i column density, ionization parameter, and stellar feedback. We find that LCEs occupy a range of stellar masses, metallicities, star formation histories, and ionization parameters, which may indicate episodic and/or different physical causes of LyC escape.

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 August 5; revised 2022 March 16; accepted 2022 March 26; published 2022 May 11. Support for this work was provided by NASA through grant No. HST-GO-15626 from the Space Telescope Science Institute. Additional work was based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute from HST proposals 13744, 14635, 15341, and 15639. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High Performance Computing at the University of Utah. The SDSS website is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration. R.A. acknowledges support from ANID Fondecyt Regular 1202007. Software: astropy (Astropy Collaboration et al. 2013, 2018), matplotlib (Hunter 2007), numpy (van der Walt et al. 2011), scipy (Virtanen et al. 2020).

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