Title: Cosmic Evolution with Gas Metallicities of Star-Forming Galaxies

　　Speaker: Dr. Chun Ly (NASA Goddard Space Flight Center)

　　Time: 2:00PM, March 17 (Monday)

　　Location: 3rd floor, middle conf. room

　　Abstract:

　　The chemical enrichment of galaxies, driven by star formation and regulated by gas outflows from supernovae and inflows from cosmic accretion, is a key process in galaxy formation that remains to be fully understood. The greatest difficulty in measuring chemical evolution is the need for rest-frame optical spectroscopy. My talk will focus on recent efforts to characterize low-mass and/or strongly star-forming galaxies, and examine their evolution across the past ten billion years. Using narrow-band imaging from the Subaru Deep Field and spectroscopy from 6-to-10 meter class telescopes, I have identified a population of extremely metal-poor galaxies at redshifts of 0.4 to 1 with detections of [OIII]4363. For their low stellar mass, I find that these galaxies have high specific SFRs (inverse ~100 Myr), high nuclear SFR surface densities, and have between one and four nearby companions within 100 kpc. I argue that galaxy-galaxy interactions are responsible for the lack of metals in the interstellar medium. In particular, these interactions can induce gravitational torques that drive metal-deficient gas from the outskirts of galaxies into the centers. I will also discuss our recent efforts to study the relationship between mass, metallicity, and SFR at z~1 from the NEWFIRM H-alpha Survey, and our current plans with Subaru's FMOS spectrograph to study the Mass-Metallicity-SFR relation at z~2.2 using more robust oxygen metallicity calibrations