Massive and Refined. II. The statistical properties of turbulent motions
  in massive galaxy clusters with high spatial resolution
  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 (e.g. Norman et al.2007). The adopted setup
allows us to study the spectral and spatial properties of turbulent motions in
galaxy clusters with unprecedented detail, achieving an maximum available
Reynolds number of the order of R=500-1000 for the largest eddies. The
correlations between the energy of these motions in the Intra Cluster Medium
and the dynamical state of the host systems are studied, and 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 (Sanders et al.2010), 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.
