Are dumbbell brightest cluster members signposts to galaxy cluster activity?

TL;DR

This study investigates whether dumbbell brightest cluster galaxies are indicators of recent galaxy cluster mergers by comparing their properties with other clusters, revealing that dumbbell galaxies often have significant peculiar velocities.

Contribution

The paper introduces a comparative analysis of dumbbell brightest cluster galaxies to assess their connection with cluster merger activity, providing new insights into cluster dynamics.

Findings

Dumbbell clusters are not more likely to show subclustering.

Dumbbell components often have significant peculiar velocities.

Dumbbell galaxies may indicate various stages of post-merger relaxation.

Abstract

We assemble a sample of galaxy clusters whose brightest members are dumbbell galaxies and compare them with a control sample in order to investigate if they are the result of recent mergers. We show that the dumbbell sample is no more likely than other clusters to exhibit subclustering. However, they are much more likely to have at least one dumbbell component possessing a significant peculiar velocity with respect to the parent cluster than a non-dumbbell brightest cluster member. We interpret this in the context of seeing the clusters at various stages of post-merger relaxation.