Magnetic turbulence in cool cores of galaxy clusters

We argue that the recently reported Kolmogorov-like magnetic turbulence spectrum in the cool core of the Hydra A galaxy cluster (Vogt & Enßlin 2005) can be understood by kinetic energy injection by active galaxies which drive a turbulent non-helical magnetic dynamo. We develop an analytical model of the turbulence in cool cores and show that it fits well to Faraday rotation magnetic field measurements and others like minimum energy estimates for a number of cool core clusters. Moreover, our model allows predictions for magnetic fields in clusters in which the appropriate observational information is still missing, it allows predictions for yet unobserved quantities like the hydrodynamical turbulence velocity and characteristic length-scale, and suggests some level of magnetic intermittency and large-scale hydrodynamic viscosity. Furthermore, the success of the model to explain the field strength in cool core clusters suggests that in general cluster magnetic fields are directly reflecting hydrodynamical turbulence, also in clusters without cool cores.