THE GALAXY LUMINOSITY FUNCTIONS DOWN TO MR = −10 IN THE COMA CLUSTER

We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to MR = −10 at three fields located at the center, intermediate, and outskirt of the cluster. The LF (−19 < MR < −10) shows no significant differences among the three fields. It shows a clear dip at MR ∼ −13 and is composed of two distinct components of different slopes; the bright component with −19 < MR < −13 has a flatter slope than the faint component with −13 < MR < −10 which has a steep slope. The bright component (−19 < MR < −13) consists mostly of red extended galaxies including few blue galaxies whose colors are typical of late-type galaxies. On the other hand, the faint component (−13 < MR < −10) consists largely of point-spread-function-like compact galaxies. We found that both these compact galaxies and some extended galaxies are present in the center while only compact galaxies are seen in the outskirt. In the faint component, the fraction of blue galaxies is larger in the outskirt than in the center. We suggest that the dwarf galaxies in the Coma Cluster, which make up the two components in the LF, are heterogeneous with some different origins.