The dynamical state of RX J1347.5-1145 from a combined strong lensing and X-ray analysis

TL;DR

This study combines strong lensing and X-ray data to analyze the complex, bimodal structure of galaxy cluster RX J1347.5-1145, revealing signs of a recent major merger and detailed temperature features.

Contribution

It provides a comprehensive combined lensing and X-ray analysis demonstrating the cluster's bimodal structure and merger activity, which was not previously characterized in detail.

Findings

Bimodal mass distribution with total mass of (9.9 ± 0.3)×10^14 M_sun/h

Detection of a hot front and cold gas filament indicating merger activity

Consistent merger scenario explaining previous mass estimate discrepancies

Abstract

We perform a combined X-ray and strong lensing analysis of RX J1347.5-1145, one of the most luminous galaxy clusters at X-ray wavelengths. We show that evidence from strong lensing alone, based on published VLT and new HST data, strongly argues in favor of a complex structure. The analysis takes into account arc positions, shapes and orientations and is done thoroughly in the image plane. The cluster inner regions are well fitted by a bimodal mass distribution, with a total projected mass of $M_{tot} = (9.9 \pm 0.3)\times 10^{14} M_\odot/h$ within a radius of $360 \mathrm{kpc}/h$ ($1.5'$). Such a complex structure could be a signature of a recent major merger as further supported by X-ray data. A temperature map of the cluster, based on deep Chandra observations, reveals a hot front located between the first main component and an X-ray emitting South Eastern sub-clump. The map also unveils a filament of cold gas in the innermost regions of the cluster, most probably a cooling wake caused by the motion of the cD inside the cool core region. A merger scenario in the plane of the sky between two dark matter sub-clumps is consistent with both our lensing and X-ray analyses, and can explain previous discrepancies with mass estimates based on the virial theorem.