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Correlation of the magnetic field and the intra-cluster gas density in galaxy clusters

K. Dolag·S. Schindler·F. Govoni·L. Feretti
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Abstract

We present a correlation between X-ray surface brightness and Faraday rotation measure in galaxy clusters, both, from radio and X-ray observations as well as from modeling of the intra-cluster medium. The observed correlation rules out a magnetic field of constant strength throughout the cluster. Cosmological, magneto-hydrodynamic simulations of galaxy clusters are used to show that for a magnetic field of cosmic origin this correlation is expected and excellently reproduces the observations showing that the RMS scatter of the Faraday rotation increases linearly with the X-ray surface brightness. From the correlation between the observable quantities, rotation measure and X-ray surface brightness, we infer a relation between the physical quantities: magnetic field and gas density. For the best available observations, those of A119, we find $B \propto n_e^{0.9}$.

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K. Dolag, S. Schindler, F. Govoni, L. Feretti. 2001-08-30. Correlation of the magnetic field and the intra-cluster gas density in galaxy clusters. https://doi.org/10.1051/0004-6361%3A20011219

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