▲ Background-corrected morphological fractions of red-sequence cluster members as a function of absolute magnitude (left) and stellar mass (right). The different panels correspond to different cluster surveys depending on redshift, as indicated in the figure. The vertical dotted lines at log (M*/M☉)=10.95 and and 11.5 indicate the stellar mass limit of the Hawk-I Cluster Survey (HCS) morphological sample and the maximum stellar mass of red-sequence galaxies in the HCS, respectively. Elliptical galaxies dominate in HCS clusters at all stellar masses while the red sequence of local clusters is dominated by ellipticals at log (M*/M☉)>11.3 and by S0s at log (M*/M☉)<11.3 (right). Disc-dominated galaxies make up to 40% of red-sequence galaxies in the intermediate redshift sample (left). Elliptical and S0 galaxies seem to follow different evolutionary histories, with intermediate-luminosity S0s likely resulting from the morphological transformation of quiescent spirals. Taken from Cerulo et al. (2017).
▲ Comparison between the red sequence number counts in clusters and in the field. Black filled circles represent the number counts of the entire Hawk-I Cluster Survey (HCS) red sequence sample, while red diamonds are the red sequence number counts in the WINGS red sequence sample. The number counts of the HCS and WINGS composite samples were obtained as in Garilli et al. (1999). Blue crosses are the red sequence number counts of passive red sequence galaxies in the COSMOS/UltraVISTA field at 0.8 < z_phot < 1.5. The number counts in the WINGS and UltraVISTA samples are normalized to match the value of the HCS number counts at approximately the Schechter turn-over magnitude M*_V. Solid lines are the best-fitting Schechter curves obtained for each sample. While no deficit of galaxies is observed in HCS with respect to WINGS, the UltraVISTA number counts decrease towards faint luminosities. This result suggests that the build-up of the red sequence is accelerated in clusters at low stellar masses. Taken from Cerulo et al. (2016).