ARlogo 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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CLUSTER MAGNETIC FIELDS

C. L. Carilli and G. B. Taylor


National Radio Astronomy Observatory, Socorro, New Mexico 87801

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

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