The Sloan Great Wall. Rich clusters

TL;DR

This study analyzes the substructure and galaxy content of ten rich clusters within the Sloan Great Wall, revealing their complex, non-virialized state and similarities with simulated dark matter haloes, highlighting ongoing formation processes.

Contribution

It provides a detailed analysis of cluster substructure, galaxy content, and peculiar velocities, and compares observed clusters with simulated dark matter haloes to understand their formation.

Findings

Clusters have multiple components with diverse galaxy content.

Some clusters show signs of ongoing mergers and infall.

Dark matter simulations reveal similar substructure formation processes.

Abstract

We present the results of the study of the substructure and galaxy content of ten rich clusters of galaxies in three different superclusters of the Sloan Great Wall. We determine the substructure in clusters using the 'Mclust' package from the 'R' statistical environment and analyse their galaxy content. We analyse the distribution of the peculiar velocities of galaxies in clusters and calculate the peculiar velocity of the first ranked galaxy. We show that clusters in our sample have more than one component; in some clusters different components also have different galaxy content. We find that in some clusters with substructure the peculiar velocities of the first ranked galaxies are large. All clusters in our sample host luminous red galaxies. They can be found both in the central areas of clusters as well as in the outskirts, some of them have large peculiar velocities. About 1/3 of red galaxies in clusters are spirals. The scatter of colours of red ellipticals is in most clusters larger than that of red spirals. The presence of substructure in rich clusters, signs of possible mergers and infall, as well as the large peculiar velocities of the first ranked galaxies suggest that the clusters in our sample are not yet virialized. We present merger trees of dark matter haloes in an N-body simulation to demonstrate the formation of present-day dark matter haloes via multiple mergers during their evolution. In simulated dark matter haloes we find a substructure similar to that in observed clusters.