The optical morphology of A3667 re-examined

TL;DR

This study uses optical spectroscopy to analyze the galaxy cluster A3667, finding a well-mixed, elongated structure with no significant substructure, supporting a merger axis near the plane of the sky.

Contribution

It provides new redshift data and a detailed optical morphology analysis, clarifying the cluster's structure and merger dynamics.

Findings

Velocity distribution fits a single Gaussian

Reduced evidence for a northwest subgroup

Cluster appears elongated and well mixed

Abstract

The galaxy cluster A3667 was observed using the Two-degree Field (2dF) multifibre spectroscopic system on the Anglo-Australian Telescope in a program designed to examine the velocity structure in the region. Specifically, we sought evidence from the optical data for the putative cluster merger believed to be responsible for the observed radio and X-ray emission. We present 184 new redshifts in the region, of which 143 correspond to member galaxies of A3667. We find the cluster velocity distribution to be well modelled by a single Gaussian in agreement with previous results. In addition, new redshift-selected isodensity plots significantly reduce the prominence of the previously reported subgroup to the north-west of the main cluster. Instead, we find the galaxy distribution to be elongated and well mixed, with a high velocity dispersion and no significant evidence for substructure. These results are consistent with the axis of the proposed merger being close to the plane of the sky.