AAS Meeting #193 - Austin, Texas, January 1999
Session 92. Clusters of Galaxies
Oral, Friday, January 8, 1999, 2:00-3:30pm, Room 9 (A and B)

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[92.03D] Combined Radio + X-ray Analysis of Magnetic Fields in Clusters of Galaxies

T. E. Clarke, P.P. Kronberg (University or Toronto), H. Böhringer (MPE)

X-ray studies of clusters of galaxies indicate that the clusters are filled with a hot, tenuous gas. This diffuse, ionized gas often extends to significant radii within the clusters (r > 1 Mpc). Radio observations of galaxy clusters reveal wide-angle-tail galaxies, head-tail galaxies, and a few cluster-wide synchrotron halos. The presence of these synchrotron halos indicates, a priori, that there are magnetic fields at some level embedded within the thermal cluster gas. This magneto-ionic region will rotate the plane of polarization of linearly-polarized emission via the Faraday effect. The presence of even weak, tangled magnetic fields within the intracluster medium can lead to dynamically important processes. The tangled fields will suppress thermal conduction, a process which can lead to the development of cooling flows in clusters. The amplified fields in the centers of cooling flows may reach equipartition with the gas pressure. Such strong magnetic fields will be dynamically important to the cluster.

We summarize our combined radio and X-ray analysis of magnetic fields within a sample of low-redshift Abell clusters. Observations of the polarized radio sources were gathered with the Very Large Array. The goal of this project is to statistically measure the magnetic field strengths and radial extent within galaxy clusters. The rotation measure data show that magnetic fields are common features in our sample of non-cooling flow clusters of galaxies. The magnetic fields appear to extend out to the edge of the X-ray emitting gas and must be ordered on fairly large scales. We will discuss some implications of the uniformity of these fields on their possible origins.

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