AAS 201st Meeting, January, 2003
Session 42. Galaxies and Clusters
Poster, Tuesday, January 7, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[42.02] Lower Cluster Magnetic Field Estimates - The Radio Galaxy Contribution

L. Rudnick (Univ. of Minnesota), K. Blundell (University of Oxford)

Analysis of rotation measure distributions in cluster radio galaxies shows that much of the rotation measure can originate from the individual radio source and its immediate environs. This result was obtained by comparing source polarization position angles to the observed rotation measures. Unless one can eliminate the individual source RM contributions, which is not possible at present, then only an upper limit to the strength of cluster-wide magnetic field fluctuations can be made. Using the same model-dependent assumptions as in the literature, we derive an upper limit of approximately 0.4 microGauss for fluctuating magnetic fields on scales of 0.5 - 3 kpc in the general Centaurus Cluster medium. Source-related Faraday rotation can arise either from a low density thermal medium mixed with the radio galaxy, or a higher density `skin' around the relativistic plasma.

This research was supported by NSF grant AST-00-71167 at Minnesota (LR) and by a University Research Fellowship from the Royal Society (KMB).

The author(s) of this abstract have provided an email address for comments about the abstract: larry@astro.umn.edu

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