Stochastic re-acceleration in the ICM

Here we suggest that efficient stochastic particle re-acceleration in galaxy clusters may be driven by compressible modes. The damping of these modes is severely dominated by the TTD-resonance with thermal electrons and protons in the ICM. However, a small energy flux of these modes may be channelled into particle re-acceleration and this gives re-acceleration times of the order of ∼ 10⁸ yrs, sufficient to mantain GeV radiating electrons in the ICM.