Magnetic Fields and Radio Halos in Galaxy Clusters

By P. C. Tribble


Direct evidence for magnetic fields in galaxy clusters is given by the existence of radio halos. Excess Faraday Rotation has also been observed in a large sample of clusters. Combined with an estimate of the tangling length of the field given by the smoothness of the radio halo, this suggests that microGauss fields tangled on 10 kpc scales are present in galaxy clusters. The origin of the field is most likely the left-over remains of old radio sources in the cluster.
This paper appeared in the Contributed Papers of the NATO ASI on Cosmical Magnetism, in honour of Professor L Mestel FRS, held in Cambridge on the 5th-9th July 1993
Peter Tribble,