Abstract

A major focus in extragalactic astrophysics and observational cosmology is the epoch of reionization of the universe. This epoch does not just represent an interesting phase-change of the neutral intergalactic medium, it is also the epoch during which the first galaxies and seed black holes formed, thus setting the starting point for all of today's studies of galaxy evolution. What are the properties of these first galaxies and black holes? It has been suggested that strongly star-forming galaxies can produce the ionizing photons needed to reionize the universe at a rate derived from estimates of the cosmic microwave background polarization. Because the leakage of Lyman continuum photons from galaxies during the epoch of reionization is not accessible to direct observations, one strategy is to find leaky galaxies at lower redshifts that serve as analogs to galaxies in the early universe. I will discuss our ongoing efforts to identify such galaxies, both with ground-based telescopes and using the Hubble Space Telescope. I will then describe the main properties of these galaxies. Comparison with stellar models permits an estimate of the amount of leaking ionizing radiation. I will conclude with an attempt to extrapolate these results to the epoch of reionization and provide directions for future research.