1206.0735 (Steven L. Finkelstein et al.)

CANDELS: The Contribution of the Observed Galaxy Population to Cosmic Reionization    [PDF]

Steven L. Finkelstein, Casey Papovich, Russell E. Ryan Jr., Andreas H. Pawlik, Henry C. Ferguson, Kristian Finlator, Anton M. Koekemoer, Mauro Giavalisco, Asantha Cooray, James S. Dunlop, Sandy M. Faber, Norman A. Grogin, Dale D. Kocevski, Jeffrey A. Newman

We present measurements of the specific ultraviolet luminosity density from a sample of 483 galaxies at 650%. Combining our observations with constraints on the emission rate of ionizing photons from Ly-alpha forest observations at z=6, we can constrain f_esc<34% (2-sigma) if the observed galaxies are the only contributors to reionization, or <13% (2-sigma) if the luminosity function extends to M_UV = -13. These escape fractions are sufficient to complete reionization by z=6. These constraints imply that the volume ionized fraction of the IGM becomes less than unity at z>7, consistent with a number of complementary reionization probes. If faint galaxies dominate reionization, future JWST observations will probe deep enough to see them, providing an indirect constraint on the ionizing photon escape fraction [abridged].

View original: http://arxiv.org/abs/1206.0735