The Galaxy Luminosity Functions down to M_R=-10 in the Coma Cluster

TL;DR

This study measures the galaxy luminosity function in the Coma Cluster down to very faint magnitudes, revealing two distinct populations of dwarf galaxies with different properties and spatial distributions.

Contribution

It provides the first detailed luminosity function of dwarf galaxies in the Coma Cluster down to M_R=-10, identifying two distinct components with different slopes and galaxy types.

Findings

The luminosity function shows no significant variation across different cluster regions.

A dip at M_R~ -13 separates two components with different slopes.

The faint component is dominated by compact, mostly blue galaxies, especially in the outskirts.

Abstract

We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to M_R=-10 at three fields located at the center, intermediate, and outskirt. The LF (-19<M_R<-10) shows no significant differences among the three fields. It shows a clear dip at M_R\sim-13, and is composed of two distinct components of different slopes; the bright component with -19<M_R<-13 has a flatter slope than the faint component with -13<M_R<-10 which has a steep slope. The bright component (-19<M_R<-13) consists of mostly red extended galaxies including few blue galaxies whose colors are typical of late-type galaxies. On the other hand, the faint component (-13<M_R<-10) consists of largely PSF-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.