%0 Journal Article
%T The mean H¦Á EW and Lyman-continuum photon production efficiency for faint z ¡Ö 4£¿5 galaxies
%A Daniel Lam
%A Guillaume Mahler
%A Ivo Labb¨¦
%A Johan Richard
%A Joop Schaye
%A Kasper B. Schmidt
%A Leindert A. Boogaard
%A Michael V. Maseda
%A Roland Bacon
%A Rychard J. Bouwens
%A Tanya Urrutia
%A Themiya Nanayakkara
%J -
%D 2019
%R 10.1051/0004-6361/201935227
%X We present the first measurements of the Lyman-continuum photon production efficiency <i>¦Î<i/><sub>ion,£¿0<sub/> at <i>z<i/>£¿¡«£¿4¨C5 for galaxies fainter than 0.2 <i>L<i/><sup>*<sup/> (£¿19 mag). <i>¦Î<i/><sub>ion,£¿0<sub/> quantifies the production rate of ionizing photons with respect to the UV luminosity density assuming a fiducial escape fraction of zero. Extending previous measurements of <i>¦Î<i/><sub>ion,£¿0<sub/> to the faint population is important, as ultra-faint galaxies are expected to contribute the bulk of the ionizing emissivity. We probe <i>¦Î<i/><sub>ion,£¿0<sub/> to such faint magnitudes by taking advantage of 200-h depth <i>Spitzer<i/>/IRAC observations from the GREATS program and ¡Ö300 3£¿< £¿<i>z<i/>£¿< £¿6 galaxies with spectroscopic redshifts from the MUSE GTO Deep + Wide programs. Stacked IRAC [3.6]£¿[4.5] colors are derived and used to infer the H<i>¦Á<i/> rest-frame equivalent widths, which range from 403 £¿ to 2818 £¿. The derived <i>¦Î<i/><sub>ion,£¿0<sub/> is log<sub>10<sub/>(<i>¦Î<i/><sub>ion,0<sub/>/Hz£¿erg<sup>£¿1<sup/>)£¿=£¿25.36£¿¡À£¿0.08 over £¿20.5£¿< £¿<i>M<i/><sub>UV<sub/>£¿< £¿£¿17.5, similar to those derived for brighter galaxy samples at the same redshift and therefore suggesting that <i>¦Î<i/><sub>ion<sub/> shows no strong dependence on <i>M<i/><sub>UV<sub/>. The <i>¦Î<i/><sub>ion,£¿0<sub/> values found in our sample imply that the Lyman-continuum escape fraction for <i>M<i/><sub>UV<sub/>£¿¡Ö£¿£¿19 star-forming galaxies cannot exceed ¡Ö8¨C20% in the reionization era
%U https://www.aanda.org/articles/aa/full_html/2019/07/aa35227-19/aa35227-19.html