The chemical evolution of the Universe – I. High column density absorbers
Article first published online: 4 APR 2002
Monthly Notices of the Royal Astronomical Society
Volume 321, Issue 4, pages 743–758, March 2001
How to Cite
Mathlin, G. P., Baker, A. C., Churches, D. K. and Edmunds, M. G. (2001), The chemical evolution of the Universe – I. High column density absorbers. Monthly Notices of the Royal Astronomical Society, 321: 743–758. doi: 10.1046/j.1365-8711.2001.04067.x
- Issue published online: 4 APR 2002
- Article first published online: 4 APR 2002
- Accepted 2000 September 20. Received 2000 September 20; in original form 2000 July 1
- galaxies: abundances;
- galaxies: dwarf;
- galaxies: evolution;
- galaxies: high-redshift;
- quasars: absorption lines
We construct a simple, robust model of the chemical evolution of galaxies from high to low redshift, and apply it to published observations of damped Lyman α quasar absorption line systems (DLAs). The elementary model assumes quiescent star formation and isolated galaxies (no interactions, mergers or gas flows). We consider the influence of dust and chemical gradients in the galaxies, and hence explore the selection effects in quasar surveys. We fit individual DLA systems to predict some observable properties of the absorbing galaxies, and also indicate the expected redshift behaviour of chemical element ratios involving nucleosynthetic time delays.
Despite its simplicity, our ‘monolithic collapse’ model gives a good account of the distribution and evolution of the metallicity and column density of DLAs, and of the evolution of the global star formation rate and gas density below redshifts z∼3. However, from the comparison of DLA observations with our model, it is clear that star formation rates at higher redshifts (z>3) are enhanced. Galaxy interactions and mergers, and gas flows very probably play a major role.