AAS 198th Meeting, June 2001
Session 38. GRBs: A Mystery and a Tool
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

[38.04] GRBs as a Means of Tracing the Metallicity History of the Universe

D. Q. Lamb (U. Chicago), D. E. Reichart (Caltech)

There is increasingly strong evidence that most GRBs are the result of the collapse of massive stars. If most GRBs are indeed due to the collapse of massive stars, one expects GRBs to occur out to redshifts z \approx 15-20. We show that both GRBs and their afterglows are very bright, and are therefore easily detectable out to such redshifts. Consequently, high dispersion spectroscopic observations of metal absorption line systems in the infrared and near infrared spectra of GRB afterglows can provide important information about the metallicity history of (1) the star-forming regions of galaxies; (2) damped Lyman alpha clouds; and (3) the Lyman alpha forest (i.e., low- to moderate-column depth clouds in the intergalactic medium). We discuss the wavelengths and the expected strengths of various metal absorption lines as a function of redshift, including the effect of the changing ionization states of these metals due to the higher densities of the clouds and the interstellar medium that are expected at very high redshifts. DER holds a Hubble Fellowship. This research was supported in part by NASA Grant NASW-4690.