Propagation of galactic cosmic rays under diffusive reacceleration

The propagation of cosmic rays in the galaxy is understood as a diffusive process where the magnetic field irregularities serve as scattering center. In this paper we pursue the idea that particles which interact with turbulent magnetic fields should naturally also gain energy due to a stochastic second-order Fermi type of acceleration. This link between diffusion and reacceleration is based on general physical principles, and we can show that the cosmic-ray data can be explained in this 'Diffusive Reacceleration Model.' As a consequence, the escape length lambdaesc(E), which defines the particles path in the galaxy, becomes a power-law in rigidity with an exponent of -1/3, which would indicate a Kolmogorov-type spectrum of magnetic turbulences. The increase of lambdaesc(E) combined with the increase of the amount of reacceleration to low energies in then interpreted as a decrease of the diffusion coefficient or an increase of the frequencies of scattering center.