Program: GN-2010A-Q-58

Damped Lyman-alpha absorbers (DLAs) observed in the spectra of quasars dominate the mass density of neutral gas in the universe. The relation of DLAs to present-day galaxies is, however, unclear. From recent observations, most DLAs appear to be metal-poor. On the other hand, several sub-DLA systems appear to be highly enriched. To understand whether this diversity in metallicity is produced by a mass-metallicity relation, or metallicity gradients, or galactic out?ows, it is essential to image their stellar content. We have recently detected several candidate DLA/sub-DLA absorber galaxies using adaptive optics imaging at Keck and Gemini. We now propose to observe candidate DLA/sub-DLA galaxies with Gemini/GMOS. These data will give redshift con?rmation, allowing us to constrain the galaxy type, star formation rate, emission-line metallicity, etc. This will help toward understanding whether the metal-rich galaxies arise in ellipticals or spirals, massive galaxies or dwarfs, and whether out?ows are important. Our data will provide the ?rst step toward a direct determination of the mass-metallicity relation for quasar absorber galaxies. We propose to obtain GMOS optical spectra of 4 candidate DLA absorber galaxies seen in previous imaging studies including our AO studies. Imaging studies suggest the brighter galaxies in the ?elds as the likely absorbing systems but in many cases do not have redshift con?rmations. It is now necessary (1) to spectroscopically con?rm the redshifts of the candidate absorbers and (2) to understand how the emission properties of the galaxies (e.g. emission-line metallicity, star formation rate) are related to the absorption-line properties (e.g. the neutral gas metallicity). The proposed GMOS data will allow us to extend a recent study where we con?rmed a DLA at z = 0.4 to be a metal-rich, vigorously star-forming galaxy with several emission lines (e.g., H-?, H-? , [O II], [O III]).