S18B0016abst
S18B0016
The ionizing output of early star-forming galaxies is key to understanding their role in cosmic reionization. The largest uncertainty is the fraction of Lyman continuum (LyC) photons that escape, fesc. As this cannot be observed directly at high redshift, in S17A we began a new MOSFIRE program to study a large sample of z≃ 3.1 Lyα emitters whose intense nebular [O iii] emission indicates they are useful analogs of early galaxies. A now completed deep HST F336W imaging program confirms that a high fraction show prominent LyC leakage. One explanation is that the star-forming regions are density- (rather than radiation-) bound which can be tested by correlating fesc with the [O iii]/[O ii] ratio. Although we completed the necessary K-band spectroscopy sampling [O iii] and Hβ, due to major technical issues we were unable to make significant progress in the H-band to secure the [O ii] strength. We thus request one final MOSFIRE night to conclude this program. Using Hβ as a measure of the number of ionizing photons per UV luminosity ξion, HST F336W for fesc and the [O iii]/[O ii] ratio, we can verify suggestions from photoionization models that [O iii] intense galaxies are powerful sources of ionizing photons and hence those beyond z=6 are capable of driving cosmic reionization.
This document was translated from LATEX by HEVEA.