# A Pre-Merger Stage Galaxy Cluster: Abell 3733

## TL;DR

This study analyzes the structure and dynamics of the galaxy cluster Abell 3733, providing evidence that it is in a pre-merger state with two sub-structures on the verge of colliding.

## Contribution

It offers a detailed multi-wavelength analysis of A3733, revealing its pre-merger status and the properties of its sub-structures, which was not previously characterized in such detail.

## Key findings

- A3733 hosts two sub-structures separated by ~0.25 Mpc.
- Both sub-structures contain cool cores and are likely to collide in 0.14 Gyr.
- The system is in a pre-merger dynamical state.

## Abstract

The galaxy cluster Abell 3733 (A3733) is a very suitable candidate in addressing dynamical processes throughout galaxy cluster mergers. This study shows structural analysis results of A3733 (z = 0.038) based on X-ray and optical data. According to X-ray luminosity map, A3733 hosts two sub-structures separated in the sky by $\sim$ 0.25 Mpc, and the two distinct clumps are located in the East (A3733E) and the West (A3733W) directions. Both sub-structures are centred on two different brightest cluster galaxies (BCGs), and the X-ray and optical centroids of both BCGs substantially coincide with each other. The intracluster medium (ICM) temperatures of the sub-structures are estimated to be 2.79 keV for A3733E and 3.28 keV for A3733W. Both sub-structures are found to be hosting cool central gas (kT $ \sim $ 1.5-2.5 keV) surrounded by hotter gas (kT $\sim $ 3.0-3.5 keV). Besides, the X-ray concentration parameters are found to be c $\sim $ 0.3 for each sub-structure. These results indicate the existence of cool centres for both sub-structures. The optical density map reveals a crowded galaxy population within the vicinity of A3733W. The high probable (% 88.2) dynamical binding model of A3733 suggests that the cores of sub-structures have a 3D separation of 0.27 Mpc and will collide in 0.14 Gyr with the relative in-falling velocity of 1936 km s$^{-1}$. As a conclusion, this study demonstrates some evidence suggesting that the A3733 system is in the pre-merger state.