Dynamical history of a binary cluster: Abell 3653

TL;DR

This study analyzes the dynamical structure of the binary galaxy cluster Abell 3653 using optical and X-ray data, revealing an ongoing merger with shock-heated gas and gravitationally bound subclusters.

Contribution

It provides a detailed multi-wavelength analysis of Abell 3653's merger dynamics, including temperature maps and a two-body dynamical model, which is novel for this cluster.

Findings

Two subclusters are gravitationally bound with 93.5% probability.

The subclusters are colliding at 2400 km/s with a near-plane-of-sky orientation.

A shock-heated gas region confirms a supersonic infall scenario.

Abstract

We study the dynamical structure of a bimodal galaxy cluster Abell 3653 at z=0.1089 by using combined optical and X-ray data. Observations include archival data from Anglo-Australian Telescope and X-ray observatories of XMM-Newton and Chandra. We draw a global picture for A3653 using galaxy density, X-ray luminosity and temperature maps. Galaxy distribution has a regular morphological shape at the 3 Mpc size. Galaxy density map shows an elongation EW direction, which perfectly aligns with the extended diffuse X-ray emission. We detect two dominant grouping around two brightest cluster galaxies (BCGs). The BCG1 (z=0.1099) can be associated with the main cluster A3653E, and a foreground subcluster A3563W concentrated at the BCG2 (z=0.1075). Both X-ray peaks are dislocated from BCGs by ($\sim$35 kpc), which suggest an ongoing merger process. We measure the subclusters' gas temperatures 4.67 and 3.66 keV, respectively. Two-body dynamical analysis shows that A3653E & A3653W are very likely (93.5% probability) gravitationally bound. The highly favoured scenario suggests that two subclusters with the mass ratio of 1.4 are colliding close to the plane of sky ($\alpha$=17$^\circ$.61) with 2400 km $s^{-1}$, and will undergo core passage in 380 Myr. Temperature map also significantly shows a shock-heated gas (6.16 keV) in between the subclusters, which confirms the supersonic infalling scenario.