Discovery of a Dissociative Galaxy Cluster Merger with Large Physical Separation

TL;DR

This paper reports the discovery of a dissociative galaxy cluster merger at z=0.53, providing insights into dark matter properties and cluster evolution through multi-wavelength observations.

Contribution

The study presents a newly discovered major dissociative galaxy cluster merger with detailed observational constraints on dark matter self-interaction.

Findings

Dark matter self-interaction cross-section constrained to ≤7 cm^2/g

Cluster observed at least 0.7 Gyr after first pass-through

Provides a detailed case of advanced cluster merger evolution

Abstract

We present DLSCL J0916.2+2951 (z=0.53), a newly discovered major cluster merger in which the collisional cluster gas has become dissociated from the collisionless galaxies and dark matter. We identified the cluster using optical and weak lensing observations as part of the Deep Lens Survey. Our follow-up observations with Keck, Subaru, Hubble Space Telescope, and Chandra show that the cluster is a dissociative merger and constrain the dark matter self-interaction cross-section {\sigma}_{DM}m_{DM}^{-1}\leq7 cm^2g^{-1}. The system is observed at least 0.7\pm0.2 Gyr since first pass-through, thus providing a picture of cluster mergers 2-5 times further progressed than similar systems observed to date. This improved temporal leverage has implications for our understanding of merging clusters and their impact on galaxy evolution.