Annu. Rev. Astron. Astrophys. 2002. 40: 319-348 Copyright © 2002 by Annual Reviews. All rights reserved

Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA

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Abstract: Magnetic fields in galaxy clusters have been measured using a variety of techniques, including: studies of synchrotron relic and halo radio sources within clusters, studies of inverse Compton X-ray emission from clusters, surveys of Faraday rotation measures of polarized radio sources both within and behind clusters, and studies of Cluster Cold Fronts in X-ray images. These measurements imply that most cluster atmospheres are substantially magnetized, with typical field strengths of order 1 µGauss with high areal filling factors out to Mpc radii. There is likely, however, to be considerable variation in field strengths and topologies both within and between clusters, especially when comparing dynamically relaxed clusters to those that have recently undergone a merger. In some locations, such as the cores of cooling flow clusters, the magnetic fields reach levels of 10-40 µG and may be dynamically important. In all clusters the magnetic fields have a significant effect on energy transport in the intracluster medium. We also review current theories on the origin of cluster magnetic fields.

Key Words : Galaxy Clusters, Magnetic Fields, Intergalactic Medium, Intracluster Medium, Cosmic Rays, Observations: Radio, X-ray

Table of Contents

• INTRODUCTION
• Synchrotron radiation
• Radio Halos
• Radio Relics
• FARADAY ROTATION
• Cluster center sources
• Background sources
• High redshift sources
• INVERSE COMPTON X-RAY EMISSION
• Electron lifetimes
• Reconciling IC and RM-derived fields
• COLD FRONTS
• MAGNETIC SUPPORT OF CLUSTER GAS AND THE BARYON CRISIS
• GZK LIMIT
• SYNHESIS
• FIELD ORIGIN
• REFERENCES