The colors of bulges and disks in the core and outskirts of galaxy clusters

TL;DR

This study investigates how environment influences the colors of bulges and disks in S0 galaxies within galaxy clusters, revealing that cluster core processes mainly affect disks, while pre-processing impacts single-component disk galaxies.

Contribution

It provides the first detailed analysis of bulge and disk colors in cluster S0 galaxies up to 2.5 R200, highlighting environmental effects on galaxy components.

Findings

Bulges are redder than disks and show no environmental dependence.

Disks become bluer with increasing cluster-centric radius, especially in cluster cores.

Pre-processing affects single-component disk-dominated galaxies beyond R200.

Abstract

The role of the environment on the formation of S0 galaxies is still not well understood, specifically in the outskirts of galaxy clusters. We study eight low-redshift clusters, analyzing galaxy members up to cluster-centric distances $\sim2.5\,R_{200}$. We perform 2D photometric bulge-disk decomposition in the $g$-, $r$- and $i$-bands from which we identify 469 double-component galaxies. We analyze separately the colors of the bulges and the disks and their dependence on the projected cluster-centric distance and on the local galaxy density. For our sample of cluster S0 galaxies, we find that bulges are redder than their surrounding disks, show a significant color-magnitude trend, and have colors that do not correlate with environment metrics. On the other hand, the disks associated with our cluster S0s become significantly bluer with increasing cluster-centric radius, but show no evidence for a color-magnitude relation. The disk color-radius relation is mainly driven by galaxies in the cluster core at $0\leq R/ R_{200}<0.5$. No significant difference is found for the disk colors of backsplash and infalling galaxies in the projected phase space. Beyond $R_{200}$, the disk colors do not change with the local galaxy density, indicating that the colors of double-component galaxies are not affected by pre-processing. A significant color-density relation is observed for single-component disk-dominated galaxies beyond $R_{200}$. We conclude that the formation of cluster S0 galaxies is primarily driven by cluster core processes acting on the disks, while evidence of pre-processing is found for single-component disk-dominated galaxies. We publicly release the data from the bulge-disk decomposition.