Elemental Abundances in GRB Afterglows and High‐Redshift DLAs

We present the results of a survey of GRB afterglows and DLA absorption line systems, in which we compare the abundances of elements from the absorbers with surveys of stars, and previous work. Our results detect high metallicity systems within GRB afterglow absorption, consistent with galactic disks having high rates of star formation and enrichment of heavy elements. We also detect some of the lowest metallicity systems yet found in DLA absorption lines, with many values of [X/H]<−2.8, including one system which has metallicity of [C/H] and [O/H} of approximately −3.5. The low metallicity DLA systems are useful for constraining nucleosynthesis from the first Pop III stars, and we compare our results with one nucleosynthesis model. Finally we describe some preliminary results from a survey of OVI absorbers within quasar Lyman alpha forest spectra, and the evidence within these spectra for low‐metallicity IGM.