Understanding the Chemical Enrichment of the early Universe

by Thomas Stanton (University of Edinburgh)

Wednesday 23 Sept 2026, 13:30 → 14:30 Europe/Stockholm

FC 61 (AlbaNova Main Building)

Chemical abundance measurements provide powerful constraints on crucial physical processes and timescales in galaxy evolution (i.e., the Baryon Cycle). Previously, most observations at high redshifts were only sensitive to the abundance of oxygen but, with the advent of JWST, it is now possible to measure the abundances of multiple elements in large samples of galaxies into the Epoch of Reionization. In this talk, I will review the current status of chemical abundance studies in the high-redshift Universe, in particular focussing on results from the JWST EXCELS survey. First, I will discuss oxygen abundances, which show clear evidence for a redshift-dependent mass metallicity relationship (MZR). I will then discuss empirical evidence for a fundamental metallicity relationship (FMR) within the EXCELS sample and discuss physical and systematic factors driving the offset of high-redshift galaxies from the locally calibrated FMR, and their implications for galaxy evolution. I will also review current attempts to identify (near-) zero metallicity systems. Beyond oxygen, I will present multi-element abundance ratios, where we find clear ⍺-enhanced non-solar abundance ratios (i.e., O/Fe, O/Ar) as expected for young, metal-poor systems in the early Universe. I will discuss the remarkable agreement between high-redshift abundance ratios, chemical evolution modelling, and local stellar archaeological data. Finally, I will review how we can understand the nebular emission of galaxies at high-redshift, and the observed evolution in classical emission-line ratios, by accounting for non-solar chemical abundance patterns in nebular modelling.