Abundances at High Redshifts: the Chemical Enrichment History of Damped Lyman-alpha Galaxies

Abstract

Damped Lyman-alpha absorption systems found in the spectra of high redshift quasars are believed to trace the interstellar gas in high redshift galaxies. In this paper, we study the elemental abundances of C, N, O, Al, Si, S, Cr, Mn, Fe, Ni, and Zn in a sample of 14 damped Lyman-alpha systems using high quality echelle spectra of quasars obtained with the 10m Keck telescope. These abundances are combined with similar measurements in the literature in order to investigate the chemical evolution of damped Lyman-alpha galaxies in the redshift range 0.7<z<4.4. Among the things investigated are: the metallicity distribution of damped Lyman-alpha galaxy, its evolution with redshift (ie, age-metallicity relation), the relative abundance patterns of the heavy metals and implications for their nucleosynthetic origin, the effects of dust, the nature of the star formation process in damped Lyman-alpha galaxies, and the nature of damped Lyman-alpha galaxies themselves.