Morphology-dependent trends of galaxy age with environment in A 901/2 seen with COMBO-17

We investigate correlations between galaxy age and environment in the A 901/2 supercluster for separate morphologies. Using COMBO-17 data, we define a sample of 530 galaxies, complete at M_V - 5 logh < -18 on an area of 3.5 × 3.5 (Mpc h^-1)². We explore several age indicators including an extinction-corrected residual from the colour-magnitude relation. As a result, we find a clear trend of age with density for galaxies of all morphologies that include a spheroidal component, in the sense that galaxies in denser environments are older. This trend is not seen among Scd/Irr galaxies since they all have young ages. However, the trend among the other types is stronger for fainter galaxies. While we also see an expected age-morphology relation, we find no evidence for a morphology-density relation at fixed age.