Graduate Student Samantha Brunker and Professor John Salzer were awarded 25 orbits with the Hubble Space telescope to search for ionizing radiation escaping from compact star-forming galaxies in the nearby Universe. Understanding the mechanisms responsible for reionization in the early universe is one of the most important questions in modern extragalactic research. Star-forming galaxies are thought to be the main contributors to this ionizing radiation. However, the exact nature of these galaxies - high mass vs. low mass - is not known. Recently, a class of compact star-bursting galaxies known as Green Peas have been shown to exhibit high Lyman-alpha and Lyman continuum escape fractions. With the existence of a low-redshift population of Lyman continuum emitting galaxies confirmed, comprehensive studies of the nature of these galaxies are needed.
Brunker and Salzer are using the Cosmic Origins Spectrograph to observe five compact star-forming galaxies to expand the number and diversity of galaxies known to emit Lyman continuum radiation. Their observations are contributing to our understanding of the escape mechanisms of ionizing radiation in galaxies, as well as providing insight into the types of sources responsible for cosmic reionization.