Stellar populations and the mass-size plane across 7 Gyr using the LEGA-C and SAMI Surveys

We investigate scaling relations between stellar population and galaxy structural parameters over a 6.7 Gyr lookback time. Specifically, we investigate the change in age and metallicity relations from z[0.60, 0.76] using the LEGA-C Survey, to low redshift using the SAMI Survey. We find that, similarly to their low-redshift counterparts, the metallicity of quiescent galaxies at z[0.60, 0.76] correlates with the gravitational potential, in that galaxies with deeper potential wells are metal enriched. This supports the theory that the relation arises due to the gravitational potential regulating the escape velocity required by metal-rich stellar and supernova ejecta to escape the system and avoid being recycled into later stellar generations. Conversely, we find no correlation between age and surface density in LEGA-C, despite there being a relation at z=0. We robustly explain our results as being a consequence of population evolution with redshift in the mass-size plane.