Cake Talk by Fergus Cullen

Galaxy metallicities, being sensitive to the interplay between

star-formation, gas accretion and galactic outflows, are an excellent

probe of the ‘baryon cycle’. To date, most observations at high

redshift have traced galaxy metallicities via the gas-phase oxygen

abundance. However, a number of recent results in the literature have

demonstrated that it is also possible to derive robust stellar iron

abundances from ultra-deep rest-frame FUV spectra. I will present

results from the VANDELS survey on the stellar mass-metallicity

relation for star-forming galaxies at z~3.5. I will also present more

recent work in which we have combined estimates of both oxygen and

iron abundances for a subset of the VANDELS galaxies, finding clear

evidence for super-solar oxygen-to-iron abundance ratios (i.e.,

𝛼-enhancement) at these redshifts.