Constraining B in galaxy clusters from statistics of giant radio halos
✍ Scribed by R. Cassano; G. Brunetti; G. Setti
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 128 KB
- Volume
- 327
- Category
- Article
- ISSN
- 0004-6337
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✦ Synopsis
Abstract
There are several possibilities to constrain the value of the magnetic field in the ICM, the most direct ones being the combination of inverse Compton and synchrotron observations, and the Faraday rotation measures. Here we discuss on the possibility to provide constraints on the magnetic field in the ICM from the analysis of the statistical properties of the giant radio halos, Mpc‐scale diffuse radio emission in galaxy clusters. Present observations of a few well studied radio halos can be interpreted under the hypothesis that the emitting relativistic electrons are re‐accelerated on their way out. By using statistical calculations carried out in the framework of the re‐acceleration model we show that the observed radiopower vs cluster mass correlation in radio halos can be reproduced only by assuming μG fields in the ICM and a scaling of the magnetic field with cluster mass B ∝ M ^b^ ~v~, with b ≥ 0.6. We also show that the expected occurrence of radio halos with mass and redshift, and their number counts are sensitive to the magnetic field strength B in massive galaxy clusters and to the scaling of B with cluster mass. Thus future deep surveys of radio halos would provide constraints on B in galaxy clusters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)