Resulting spectral stacks (normalised by the flux at 4150 Å < λ <  4350 Å) around the [OII] doublet in bins of stellar mass (left panel) and in bins of local density (right panel). This figure shows the comparison between different stacks (for individual inspection, we refer to Fig. C.1). We see a strong dependence of the [OII] strength on the stellar mass with higher-stellar-mass galaxies having weaker [OII] emission, as expected since most quenched galaxies are found at higher stellar masses and should have little to no emission. We also find a dependence of the [OII] strength on the local density with high-density regions having galaxies with weaker [OII] emission, again with massive quiescent galaxies dominating at higher densities being the likely cause of this effect.