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| Paper: |
Low (and High) Metallicity Galaxies at High Redshift |
| Volume: |
353, Stellar Evolution at Low Metallicity: Mass Loss, Explosions, Cosmology |
| Page: |
363 |
| Authors: |
Pettini, M. |
| Abstract: |
The past few years have seen a steady progress in the determination of element abundances at high redshifts, with new and more accurate measures of metallicities in star-forming galaxies, in QSO absorbers, and in the intergalactic medium. We have also become more aware of the limitations of the tools at our disposal in such endeavours. I summarise these recent developments, focusing in particular on the clues which chemical abundance studies offer to the links between the high redshift galaxy populations and today's galaxies. The new data are 'fleshing out' the overall picture of element abundances at redshifts z = 2 − 3 which has been gradually coming into focus over the last decade. The main conclusion is that high redshift does not necessarily mean metal-poor: while there is some redshift evolution in the mean abundances of different populations of galaxies, it amounts to only about 0.1 dex in the overall metallicity Z per unit redshift from z = 3 to the present. Much more important in determining the degree of metal enrichment is the overall depth of the potential well in which baryons find themselves: at any one epoch the metallicity measured can vary by more than three orders of magnitudes depending on the overdensity (relative to the cosmic mean) of the structures considered. |
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