The Low-redshift Lyman Continuum Survey. II. New Insights into LyC Diagnostics
Sophia R. Flury, Anne E. Jaskot, Henry C. Ferguson, G. Worseck, Kirill Makan, John Chisholm, Alberto Saldana-Lopez, D. Schaerer, Stephan R. McCandliss, Xinfeng Xu, Bingjie Wang, M. S. Oey, Nicole M. Ford, Timothy M. Heckman, Zhiyuan Ji, Mauro Giavalisco, R. Amorín, Hakim Atek, J. Blaizot, Sanchayeeta Borthakur, Cody Carr, M. Castellano, S. de Barros, Mark Dickinson, Steven L. Finkelstein, Brian Fleming, Fabio Fontanot, Thibault Garel, A. Grazian, Matthew Hayes, Alaina Henry, Valentin Mauerhofer, Genoveva Micheva, Göran Östlin, Casey Papovich, L. Pentericci, Swara Ravindranath, Joakim Rosdahl, Michael J. Rutkowski, P. Santini, Claudia Scarlata, Harry I. Teplitz, T. X. Thuan, Maxime Trebitsch, E. Vanzella, Anne Verhamme
Abstract
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 Ly α , 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.