Cosmic Ray propagation in magneto-hydrodynamic turbulence

Abstract

Cosmic-Ray mean free paths in magnetized sub-Alfvénic turbulence are calculated using direct numerical simulations coupling kinetic and magnetohydrodynamic (MHD) calculations.The mean free paths are reconstructed by averaging over a large number of particle trajectories and several magnetic realizations. Our solutions depend on the geometry of the turbulence forcing: either compressible or solenoidal. Our results in the compressible forcing case are found to be compatible with the predictions of the quasi-linear theory (QLT), whereas solenoidal forcing solutions are not. This underlines the influences of the different MHD modes over the particle scattering process.