DIFFERENCES IN THE LUMINOSITY FUNCTIONS OF FAINT EARLY-TYPE AND FAINT LATE-TYPE GALAXIES IN FOUR NEARBY CLUSTERS OF GALAXIES

摘要

We have carried out a photometric survey of four nearby clusters of galaxies, A1656, A1367, A1644, and A1631, with mosaic CCD cameras. The observed luminosity functions of A1656, A1367, and A1631 cannot be approximated by the Schechter function with α = -1.25 over the whole magnitude range -21.5 ≤ M_R ≤ -16.0, although the bright parts (M_R ≤ -18) have a Schechter form in all of the four clusters. The luminosity functions of late-type galaxies have a similar shape for all the clusters, while those of faint early-type galaxies (M_R ≥ -18) show a large variation from cluster to cluster. Only A1644 lacks the faint early-type galaxies, and its luminosity function is in the Schechter form over all of the magnitude range observed.