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V. P. Kulkarni (Univ. of South Carolina), S. M. Fall (Space Telescope Science Institute)
We examine the existing measurements of Zinc abundances in quasar damped Lyman-alpha (DLA) absorbers to investigate whether the metallicity in the absorber galaxies evolves with time. Most models of cosmic chemical evolution predict that the mass-weighted mean metallicity of galaxies rises with time, from low values at high redshifts to near-solar values at z = 0. However there has been considerable debate about whether or not the observations of DLA absorbers actually show evolution in the metallicity. The main problem is that the effective number of systems which dominate the H I column-density-weighted mean metallicity is very small. We have used the existing data to quantify the mean metallicity-redshift relation and its uncertainties, taking into account both measurement errors and sampling errors. We find that the slope values for the mean metallicity-redshift relation are consistent at \le 2 \sigma levels with both no evolution as well as the rates predicted by recent models of cosmic chemical evolution. Thus a wider range of evolutionary rates are allowed by present data than the lack of evolution claimed in previous studies.