The Evolution of Cluster Dwarfs

We summarize the results from analyzing six clusters of galaxies at 0.14 < z < 0.40 observed with the Hubble Space Telescope Advanced Camera for Surveys. We derive deep composite luminosity functions in B, g, V, r, i and z down to absolute magnitude of ∼ -14 + 5 log h mag. The luminosity functions are fitted by a single Schechter function with M∗ BgV riz = −19.8, −20.9, −21.9, −22.0, −21.7, and −22.3 mag. and α ∼ −1.3 for all bands. The data suggests red sequence dominates the luminosity function down to ≥ 6 mag. below L∗, the dwarf spheroidals regime. Hence, at least at z ∼ 0.3, the red sequence is well established and galaxies down to dwarf spheroidals are assembled within these clusters. We do not detect the faint-end upturn (M > −16) that is observed in lower redshift clusters. If this is real, the faint-end population has originated since z = 0.3.