This project, renewing a previous award, will continue work on the problem of how mass, energy, and elements heavier than helium ("metals") cycle in and out of galaxies over the interval when half the stellar mass now present in galaxies was forming. Under the prior award, the proposing team acquired spectra of several hundred galaxies in the relevant range of redshifts. They will use these data to extend the galaxy mass-metallicity relation to lower stellar masses, and will investigate the effect of shock excitation on metallicity diagnostics using both existing and new integral-field spectroscopic data. New observations will be obtained using new instrumentation becoming available at the Keck Observatory and on the Very Large Telescope, with an emphasis on detailed follow-up spectroscopy. The team will make use of fluorescent line emission to try to resolve discrepant galactic wind velocities obtained from absorption lines partially filled by emission, and will improve their modeling of line profiles, by adapting a theory developed for hot star winds and also by numerical ray tracing through a 3-dimensional hydrodynamic simulation. As a byproduct, the team will improve knowledge of the scaling relations between outflow properties and galaxy properties, and constrain the physical nature of the acceleration mechanism. The project provides support for the third year of a Postdoctoral Scholar appointment for a female scientist and funds the dissertation research of a graduate student; and the Principal Investigator will continue her program of community outreach activities. The team intends to make their line-fitting code and the data from their survey for ultra-faint, emission-line galaxies publically available.
