LEGA-C stellar population scaling relations. II

Relying on a consistent analysis of SDSS DR7 spectra and accounting for aperture corrections, we quantified the evolution of the volume-weighted stellar age and stellar metallicity scaling relations between z=0.7 and the present. We found negligible evolution in the stellar metallicity-mass relation of quiescent galaxies and for M*>10^11^M_{sun}_ galaxies in general. Lower-mass star-forming galaxies instead have typically lower metallicities than their local counterparts, indicating significant enrichment since z~0.7 in the low-mass regime.

Notably, the median of the stellar ages of the general population and of quiescent galaxies has changed by only 2Gyr between z=0.7 and z=0.1, which is less than expected from cosmic ageing. Some quiescent galaxies must evolve passively to reach the old boundary of the local population. In order to explain the evolution of the median trends, however, both individual evolution through rejuvenation and/or minor merging that affects the outer galaxy regions and population evolution through quenching of massive metal-rich star-forming galaxies are required.