  1) Background: the budget of non-thermal energy in galaxy clusters is not
well constrained, owing to the observational and theoretical difficulties in
studying these diluted plasmas on large scales. 2) Method: we use recent
cosmological simulations with complex physics in order to connect the emergence
of non-thermal energy to the underlying evolution of gas and dark matter. 3)
Results: the impact of non-thermal energy (e.g. cosmic rays, magnetic fields
and turbulent motions) is found to increase in the outer region of galaxy
clusters. Within numerical and theoretical uncertainties, turbulent motions
dominate the budget of non-thermal energy in most of the cosmic volume. 4)
Conclusion: assessing the distribution non-thermal energy in galaxy clusters is
crucial to perform high-precision cosmology in the future. Constraining the
level of non-thermal energy in cluster outskirts will improve our understanding
of the acceleration of relativistic particles by cosmic shocks and of the
origin of extragalactic magnetic fields.
