The Kaleidoscope Survey: Strong Gravitational Lensing in Galaxy Clusters with Radial Arcs

TL;DR

This study measures dark matter profiles in six galaxy clusters using strong lensing and BCG kinematics, revealing core-like density profiles and demonstrating the importance of combined observational techniques for understanding cluster mass distributions.

Contribution

First strong lensing analysis of two clusters and a comprehensive method combining imaging and kinematics to disentangle baryonic and dark matter in cluster cores.

Findings

Dark matter density profiles are core-like with an average slope of ~0.66.

Total mass profiles are consistent with previous combined lensing and kinematic studies.

Galaxy-scale kinematics help separate baryonic and dark matter in cluster centers.

Abstract

We measure the dark matter density profiles of six galaxy clusters: A383, MS 2137-23, MACS J0326.8-0043, MACS J1427.6-2521, MACS J0417.5-1154, and MACS J0949.8+1708. Each cluster contains at least one radial arc, a unique physical feature that allows for more precise measurements of the inner mass profile (R < 50 kpc) from strong lensing. We present the first strong lensing analysis for MACS J0326 and MACS J1427. We use a combination of HST imaging and VLT/MUSE observations from the ESO Kaleidoscope Clusters Survey, a large `filler' program, to identify and measure redshifts for multiply-imaged systems and obtain the 2-D stellar velocity dispersion for each centrally-located brightest cluster galaxy (BCG). The BCG kinematics are used to subtract the baryonic mass component from the inner mass profile. We find total mass density profiles consistent with previous works using a combination of strong lensing and BCG kinematics. The overall shape of these profiles appears core-like, with an average dark matter slope measurement of $\gamma$~0.66. These results demonstrate the ongoing need for the construction of observational models for galaxy clusters, and show how galaxy-scale kinematics can be used to disentangle baryonic and dark matter concentrations in cluster cores.