Constraints on Early Nucleosynthesis from the Abundance Pattern of a   Damped Ly-alpha System at z = 2.626
  We have investigated chemical evolution in the young universe by analysing the detailed chemical enrichment pattern of a metal-rich galaxy at high redshift. The recent detection of over 20 elements in the gas-phase of a damped Lyman-alpha absorber (DLA) at z = 2.626 represents an exciting new avenue for exploring early nucleosynthesis. Given a strict upper age of ~2.5 Gyr and a gas-phase metallicity about one third solar, we have shown the DLA abundance pattern to be consistent with the predictions of a chemical evolution model in which the interstellar enrichment is dominated by massive stars with a small contribution from Type Ia supernovae. Discrepancies between the empirical data and the models are used to highlight outstanding issues in nucleosynthesis theory, including a tendency for Type II supernovae models to overestimate the magnitude of the "odd-even" effect at subsolar metallicities. Our results suggest a possible need for supplemental sources of magnesium and zinc, beyond that provided by massive stars. 
Yeshe Fenner (1 and 2), Jason X. Prochaska (2), Brad K. Gibson (1)   ((1) Swinburne University, (2) UCO/Lick Observatory)