The evolution of cluster dwarfs

TL;DR

This study analyzes galaxy clusters at intermediate redshifts, revealing that the red sequence is fully developed down to dwarf spheroidals by z=0.3, with no faint-end upturn observed, indicating galaxy assembly over time.

Contribution

It provides the first detailed luminosity functions of cluster galaxies at 0.14<z<0.40 across multiple bands, highlighting the evolution of the faint galaxy population.

Findings

Red sequence dominates down to dwarf spheroidals at z=0.3.

No faint-end upturn observed at M > -16 in these clusters.

Luminosity functions fit by a single Schechter function with consistent alpha.

Abstract

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 an absolute magnitude of -14 +5 log h mag. The luminosity functions are fitted by a single Schechter function with M^*=-19.8,-20.9,-21.9, -22.0,-21.7 and -22.3 i B,g,V.r,i,z respectively and alpha=-1.3 for all bands. The data suggest that the red sequence dominates the luminosity function down to more than 6 mag. below L*, the dwarf spheroidal regime. Hence, at least at z=0.3 the red sequence is well established and galaxies down to dwarf spheroidals are fully 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.