The evolution of global metallicities & metallicity profiles in disc galaxies: Insights from simulations & observations

In this talk, I will present recent work on the evolution of global metallicities and radial metallicity profiles in galaxies from high redshift to the present day. This study combines insights from the newly-improved L-Galaxies 2020 semi-analytic model of galaxy formation (which includes delayed enrichment of multiple chemical elements from SNe and stellar winds) with the latest observational chemical data for gas and stars in and around galaxies. At low redshift, L-Galaxies 2020 is compared to the mass - metallicity relation and radial profiles revealed by IFUs such as MaNGA and MUSE. At higher redshift, direct absorption-line-based metallicity measurements from QSO and GRB DLAs are used. Such measurements are ideal precursors to future high-redshift observations with JWST. Our study reveals that a very efficient direct enrichment of the circumgalactic medium (CGM) by SNe is required in L-Galaxies 2020, in order to simultaneously reproduce the chemical composition found in and around galaxies back to z=2-3. I will discuss how this requirement affects feedback energetics and mass-loading factors, and compare our findings to those from other semi-analytic models and hydrodynamical simulations. Importantly, I will also discuss how a reduction in the maximum SN-II progenitor mass in L-Galaxies 2020 can improve modelled radial profiles at large radii, and also how the assumed stellar yields can have a significant impact on the expected chemical abundances and N/O ratios.