0 Assigned ID: 262 ----- Attempting Submission 1 (Thu Apr 09 21:02:33 GMT 2015) ----- HST Phase I Proposal 262 (phase1-AR_sub1.pdf.apt) successfully submitted. Receipt: # 262-1 ----- Attempting Submission 2 (Fri Apr 10 21:34:00 GMT 2015) ----- HST Phase I Proposal 262 (phase1-AR_sub1.pdf.apt) successfully submitted. Receipt: # 262-2 ----- Attempting Submission 3 (Fri Apr 10 23:57:00 GMT 2015) ----- Phase II ID is a required field. Couldn't identify "AR" as a legal selection. Observing Description is a required field. 0 For cosmic reionization to be complete by a redshift of ~6, the escape fraction of ionizing photons from starburst dwarf galaxies in the early universe is expected to be higher than ~20%. However, measurements of the escape fraction from analogous galaxies are poorly constrained, and suggest dramatically lower escape fractions than expected, in the few cases where the escaping photons can be detected at all. These measurements are largely inconclusive because they are forced to rely on a number of coarse assumptions that can strongly bias results to low escape fractions. We propose to remedy this situation by developing an entirely new methodology that (1) uses spectral energy distribution fitting of resolved stars to infer both the production of ionizing photons and their absorption by dust and (2) uses narrow band images of Balmer lines to track the absorption of ionizing photons by neutral gas. These measurements allow us to derive maps of the ionizing escape fraction across the face of a galaxy, while avoiding assumptions about dust geometry and systematic errors inherent in using spatially-averaged spectra to infer the ionizing photon production rate. We will develop and test the needed machinery in the nearby starburst galaxy NGC 4214. Using this galaxy as a test case, we can shed light on limitations in traditional methodologies by comparing to the results from our new method. Once developed, this simpler methodology can easily be applied to a much larger sample of nearby galaxies, allowing a broad attack on understanding this important but elusive process. UNRESOLVED STAR FORMATION 0 Regular false true false false false SUPPORTED