Chemical Elements at High and Low Redshifts

TL;DR

Recent advances in measuring element abundances at high redshifts have improved our understanding of cosmic chemical evolution, revealing that at least 40% of the universe's metals are accounted for by z=2.5.

Contribution

This paper summarizes recent progress in high-redshift chemical abundance measurements and discusses their implications for galaxy evolution and metal distribution.

Findings

At least 40% of metals from star formation are accounted for by z=2.5.

New data clarify the link between high-redshift galaxies and present-day galaxies.

Limitations of current tools are acknowledged and discussed.

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 and--in tune with the theme of this meeting--consider 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. In particular, we can now account for at least 40% of the metals produced by the global star formation activity in the universe from the Big Bang to z = 2.5, and we have strong indications of where the remainder are likely to be found.