Multi-Phenomena Modeling of the New Bullet Cluster, ZwCl008.8+52, using N-body/hydrodynamical Simulations

TL;DR

This study uses hydrodynamical and N-body simulations to model the merging galaxy cluster ZwCl 0008, successfully reproducing multi-wavelength observations and providing insights into dark matter's collisionless nature.

Contribution

It presents a detailed simulation-based model of ZwCl 0008, offering new constraints on collision parameters and supporting the collisionless dark matter hypothesis.

Findings

Simulations match radio, X-ray, and lensing observations.

The cluster's mass is about 70% lower than the Bullet cluster.

Dark matter appears effectively collisionless on large scales.

Abstract

We use hydrodynamical/N-body simulations to interpret the newly discovered Bullet-cluster-like merging cluster, ZwCl 0008.8+5215 (ZwCl 0008 hereafter), where a dramatic collision is apparent from multi-wavelength observations. We have been able to find a self-consistent solution for the radio, X-ray, and lensing phenomena by projecting an off-axis, binary cluster encounter viewed just after first core passage. A pair radio relics traces well the leading and trailing shock fronts that our simulation predict, providing constraints on the collision parameters. We can also account for the observed distinctive comet-like X-ray morphology and the positions of the X-ray peaks relative to the two lensing mass centroids and the two shock front locations. Relative to the Bullet cluster, the total mass is about 70% lower, ($1.2\pm0.1) \times 10^{15}$ Msun, with a correspondingly lower infall velocity, $1800\pm300$ km/s, and an impact parameter of $400\pm100$ kpc. As a result, the gas component of the infalling cluster is not trailing significantly behind the associated dark matter as in the case of the Bullet cluster. The degree of agreement we find between all the observables provides strong evidence that dark matter is effectively collisionless on large scales calling into question other claims and theories that advocate modified gravity.