The Galaxy Population of Low-Redshift Abell Clusters

TL;DR

This study analyzes the luminosity and color distribution of galaxies in 57 low-redshift Abell clusters, revealing how galaxy populations vary with cluster radius and environment, challenging simple evolutionary models.

Contribution

It introduces a comprehensive analysis of galaxy color and luminosity distributions in low-redshift clusters, highlighting the complex environmental effects on galaxy evolution.

Findings

Red and blue dwarf-to-giant ratios are independent of cluster richness.

DGR decreases in the cluster core for red galaxies, but blue DGR remains nearly constant.

Blue galaxy fraction declines towards the cluster center, especially for giant galaxies.

Abstract

We present a study of the luminosity and color properties of galaxies selected from a sample of 57 low-redshift Abell clusters. We utilize the non-parametric dwarf-to-giant ratio (DGR) and the blue galaxy fraction (fb) to investigate the clustercentric radial-dependent changes in the cluster galaxy population. Composite cluster samples are combined by scaling the counting radius by r200 to minimize radius selection bias. The separation of galaxies into a red and blue population was achieved by selecting galaxies relative to the cluster color-magnitude relation. The DGR of the red and blue galaxies is found to be independent of cluster richness (Bgc), although the DGR is larger for the blue population at all measured radii. A decrease in the DGR for the red and red+blue galaxies is detected in the cluster core region, while the blue galaxy DGR is nearly independent of radius. The fb is found not to correlate with Bgc; however, a steady decline toward the inner-cluster region is observed for the giant galaxies. The dwarf galaxy fb is approximately constant with clustercentric radius except for the inner cluster core region where fb decreases. The clustercentric radial dependence of the DGR and the galaxy blue fraction, indicates that it is unlikely that a simple scenario based on either pure disruption or pure fading/reddening can describe the evolution of infalling dwarf galaxies; both outcomes are produced by the cluster environment.