Dependence of the Build-up of the Colour-Magnitude Relation on Cluster Richness at z ~ 0.8

Understand

We present environmental dependence of the build-up of the colour-magnitude relation (CMR) at z ~ 0.8.

• It is well established that massive early-type galaxies exhibit a tight CMR in clusters up to at least z ~ 1.
• The faint end of the relation, however, has been much less explored especially at high redshifts primarily due to limited depths of the data.
• Some recent papers have reported a deficit of the faint red galaxies on the CMR at 0.8 < z < 1, but this has not been well confirmed yet and is still controversial.