Properties of the Dwarf Galaxy Population in Galaxy Clusters

TL;DR

This study analyzes the properties and distribution of dwarf galaxies in galaxy clusters, revealing color-based population differences and their potential evolutionary links with high-redshift clusters.

Contribution

It provides the largest spectroscopic sample of cluster dwarf galaxies and examines their color, distribution, and environmental dependence, highlighting evolutionary connections.

Findings

Red dwarf galaxies share environments with bright cluster members.

Dwarf-to-giant ratio varies with clustercentric distance.

Red dwarf fraction is higher in cluster centers.

Abstract

We present the observational properties of the dwarf galaxy population (Mr > M*+1) corresponding to one of the largest samples of spectroscopically confirmed galaxy cluster members reported in the literature. We have observed that red dwarf galaxies (u-r > 2.22) share the same cluster environment as the brightest cluster members (Mr < -21), but are not in dynamical equilibrium. We computed the dwarf-to-giant ratio (DGR) using a spectroscopically selected sample. The DGR was found to vary with clustercentric distance, essentially due to the blue dwarf population (u-r < 2.22). The u-r color of red dwarf galaxies was independent of their environment and similar to the color of red isolated dwarfs. Blue dwarf galaxies located outside r200 show similar u-r colors to those of the field population, while strong reddening was observed toward the cluster center. We also present evidence that the fraction of red to blue dwarf galaxies in clusters is larger in the innermost cluster regions. We conclude that the present red dwarf population observed in the central regions of nearby galaxy clusters could be related to the blue dwarf population observed in clusters at high redshift.