Cosmic-ray Transport in Magnetohydrodynamic Turbulence

Abstract This paper studies cosmic-ray (CR) transport in magnetohydrodynamic (MHD) turbulence. CR is strongly dependent on the properties of magnetic We perform test particle simulations to study interactions with both total MHD turbulence and decomposed modes. The spatial diffusion coefficients pitch angle scattering are calculated from trajectories Our results confirm that fast modes dominate propagation, whereas Alfvén slow much less efficient have shown similar pitch-angle rates. investigate cross field large small scales. On large/global scales, normal observed coefficient suppressed by M A ? compared parallel coefficients, ? closer 4 than turbulence, as theoretically expected. For scales smaller injection scale, local global reference frames adopted. Superdiffusion such all cases. Particularly, show clear Richardson frame. transitions smoothly Richardson’s one index 1.5 mean free path decreases ? ? ? L ? , where injection/coherence length broad applications CRs various astrophysical environments.