Searching for MgII absorbers in and around galaxy clusters

TL;DR

This study analyzes MgII absorbers in and around galaxy clusters using SDSS data, revealing higher detection rates inside clusters but smaller halo sizes, suggesting environmental truncation of galaxy halos.

Contribution

It provides the first large-scale statistical analysis of MgII absorbers in cluster environments, highlighting the impact of clusters on galaxy halo sizes.

Findings

MgII absorbers are more abundant inside clusters.

Galaxy halo sizes are reduced by about 30% in clusters.

Absorber-to-galaxy ratio is low inside clusters.

Abstract

To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars and cluster galaxies from the SDSS. With ~82 000 quasar spectra, we detect 197 MgII absorbers in and around the clusters. The detection rate per quasar is 2.7$\pm$0.7 times higher inside the clusters than outside the clusters, indicating that MgII absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that MgII absorbers are mainly contributed by the CGM of massive star-forming galaxies, a typical halo size of cluster galaxies is smaller than that of field galaxies by 30$\pm$10 per cent. This finding supports that galaxy haloes can be truncated by interaction with the host cluster.