Monday, April 16, 2012
Astronomy Tea Talk
Heavy-Element Enrichment in the Early Universe Observed with FIRE
Rob Simcoe, MIT
The two clearest signatures of stars in the early universe are their radiation and their synthesized heavy elements. The light may be studied indirectly via hydrogen reionization, but characterization of chemicals at high redshift requires deep infrared spectroscopy, which until now has been limited by instrument sensitivity. To address this issue, my group built the Folded-Port Infrared Echellette (FIRE) for Magellan. FIRE is a scientifically versatile facility instrument, which by design is also optimal for studies of quasar absorption lines at the highest possible redshifts. I will describe new results from our ongoing programs during FIRE's first 1.5 years of operation. In this time, we have extended studies of circum-galactic metal pollution seen in MgII - previously only characterized at z < 2 - out to z=5.5. We have used this additional redshift path to examine whether MgII systems are an observational manifestation of galaxy formation feedback in the early universe. Using separate observations, we have also substantially tightened constraints on the CIV mass density and intergalactic carbon enrichment at z = 5.0-6.5. Finally I will present new measurements of chemical abundances at z ~ 7 and discuss them in the context of reionization and the formation of the first stars.