Strong Magnetization Measured in the Cool Cores of Galaxy Clusters

TL;DR

This paper investigates cold fronts in galaxy clusters and finds evidence of strong magnetic fields below these fronts, which help stabilize them and may explain their association with radio minihalos.

Contribution

The study provides the first comprehensive analysis of thermal profiles across cold fronts, revealing significant magnetic pressure contributions in cool-core galaxy clusters.

Findings

Detection of small thermal pressure drops below cold fronts

Evidence of magnetic fields carrying 10-20% of the pressure

Magnetic stabilization of cold fronts and connection to radio minihalos

Abstract

Tangential discontinuities, seen as X-ray edges known as cold fronts (CFs), are ubiquitous in cool-core galaxy clusters. We analyze all 17 deprojected CF thermal profiles found in the literature, including three new CFs we tentatively identify (in clusters A2204 and 2A0335). We discover small but significant thermal pressure drops below all nonmerger CFs, and argue that they arise from strong magnetic fields below and parallel to the discontinuity, carrying 10%-20% of the pressure. Such magnetization can stabilize the CFs, and explain the CF-radio minihalo connection.