An Optical Analysis of the Merging Cluster Abell 3888

TL;DR

This study uses spectroscopy to analyze the structure and dynamics of the galaxy cluster Abell 3888, revealing it as a merging system with multiple substructures and identifying new galaxy over-densities.

Contribution

The paper provides new spectroscopic data and a detailed substructure analysis of Abell 3888, confirming its merging state and discovering additional galaxy clusters.

Findings

A3888 has a redshift of 0.1535 and velocity dispersion of 1181 km/s.

The cluster is elongated and bimodal, indicating a merger.

Six new galaxy over-densities, including three new clusters, were identified.

Abstract

In this paper we present new AAOmega spectroscopy of 254 galaxies within a 30' radius around Abell 3888. We combine these data with the existing redshifts measured in a one degree radius around the cluster and performed a substructure analysis. We confirm 71 member galaxies within the core of A3888 and determine a new average redshift and velocity dispersion for the cluster of 0.1535 +\- 0.0009 and 1181 +\- 197 km/s, respectively. The cluster is elongated along an East-West axis and we find the core is bimodal along this axis with two sub-groups of 26 and 41 members detected. Our results suggest that A3888 is a merging system putting to rest the previous conjecture about the morphological status of the cluster derived from X-ray observations. In addition to the results on A3888 we also present six newly detected galaxy over-densities in the field, three of which we classify as new galaxy clusters.