Massive and Refined. II. The statistical properties of turbulent motions in massive galaxy clusters with high spatial resolution

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  • 28 October 2010
Abstract
We study the properties of chaotic motions in the intra cluster medium using a set of 20 galaxy clusters simulated with large dynamical range, using the Adaptive Mesh Refinement code ENZO. The spectral and spatial properties of chaotic and turbulent motions in galaxy clusters are described with unprecedented detail, with an available Reynolds number of Re=1600 for the largest eddies, and correlations between the energy of these motions in the Intra Cluster Medium and the dynamical state of the host systems are found. The statistical properties of turbulent motions and their evolution with time support that major merger events are responsible for the injection of the bulk of turbulent kinetic energy inside cluster. Turbulence is found to account for a 20-30 per cent of the thermal energy in merging clusters, while it accounts for a 5 per cent in relaxed clusters. A comparison of the energies of turbulence and motions in our simulated clusters with present upper-limits in real nearby clusters, recently derived with XMM-Newton, is provided. When the same spatial scales of turbulent motions are compared, the data from simulations result well within the range presently allowed by observations. Finally, we comment on the possibility that turbulence may accelerate relativistic particles leading to the formation of giant radio halos in turbulent (merging) clusters. Based on our simulations we confirm previous semi-analytical studies that suggest that the fraction of turbulent clusters is consistent with that of clusters hosting radio halos.

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