Dark Matter and Baryons in the Most X-ray Luminous and Merging Galaxy Cluster RX J1347.5-1145

TL;DR

This study combines high-resolution lensing and X-ray data to map the mass distribution of the massive galaxy cluster RX J1347.5-1145, confirming the agreement between lensing and X-ray mass estimates and analyzing dark matter and baryons.

Contribution

It provides the most detailed mass map of the cluster's core to date, integrating strong and weak lensing with X-ray data, and compares dark matter profiles with theoretical models.

Findings

Lensing and X-ray mass estimates agree within 400 kpc.

Dark matter and baryons are centered on the BCG within <10 kpc.

Dark matter profile fits both NFW and cored models.

Abstract

The galaxy cluster RX J1347-1145 is one of the most X-ray luminous and most massive clusters known. Its extreme mass makes it a prime target for studying issues addressing cluster formation and cosmology. In this paper we present new high-resolution HST/ACS and Chandra X-ray data. The high resolution and sensitivity of ACS enabled us to detect and quantify several new multiply imaged sources, we now use a total of eight for the strong lensing analysis. Combining this information with shape measurements of weak lensing sources in the central regions of the cluster, we derive a high-resolution, absolutely-calibrated mass map. This map provides the best available quantification of the total mass of the central part of the cluster to date. We compare the reconstructed mass with that inferred from the new Chandra X-ray data, and conclude that both mass estimates agree extremely well in the observed region, namely within 400 / h_70 kpc of the cluster center. In addition we study the major baryonic components (gas and stars) and hence derive the dark matter distribution in the center of the cluster. We find that the dark matter and baryons are both centered on the BCG within the uncertainties (alignment is better than <10 kpc). We measure the corresponding 1-D profiles and find that dark matter distribution is consistent with both NFW and cored profiles, indicating that a more extended radial analysis is needed to pinpoint the concentration parameter, and hence the inner slope of the dark matter profile.