Radiative feedback from massive stars is energetically fundamental to galaxy and cosmic evolution, and it also provides essential emission-line diagnostics of conditions both locally and in the distant universe. Our current limited understanding of radiative feedback greatly hampers investigations of present-day local processes as well as of galaxy formation and the early universe. Dr. Sally Oey, at Lowell Observatory, will carry out a comprehensive investigation of radiative feedback processes ranging from specific nebular ionization conditions to large-scale, global ionization processes in galaxies and the intergalactic medium. The goals are: 1) To understand specifically how ionizing spectral types and chemical abundances affect nebular emission, and to calibrate corresponding nebular line diagnostics; and 2) to understand global radiative feedback processes in galaxies by investigating large-scale properties of diffuse ionized gas, HII region populations, and implications for the escape of ionizing photons from galaxies. ***
