Description
Elemental abundance ratios provide a unique constraint on the rate of enrichment via different physical processes (e.g. CCSNe vs Type-Ia SNe), yielding insights into galaxy evolution, star-formation timescales and chemical enrichment. At $z>2$, most observations are sensitive to the oxygen abundance, though recent developments in methodology and the advent of JWST spectroscopy have enabled the measurements of additional elements (e.g., Fe, Ne and Ar) at these redshifts. I will present measurements of O, Fe, Ar and Ne abundances for star-forming galaxies at $2 < z < 6$ from the NIRVANDELS and JWST/EXCELS surveys. These results show clear evidence of O-enhanced non-solar abundance ratios (i.e., O/Fe and O/Ar) as expected for young systems in the early Universe. I will also discuss the remarkable agreement of high-redshift abundance ratios with chemical evolution models and Milky Way galactic archaeological data. Finally, I will comment on the importance and implications of non-solar abundance ratios on our understanding of the first galaxies.
