Anisotropic diffusion of galactic cosmic ray protons and their   steady-state azimuthal distribution
  Galactic transport models for cosmic rays involve the diffusive motion of these particles in the interstellar medium. Due to the large-scale structured galactic magnetic field this diffusion is anisotropic with respect to the local field direction. We included this transport effect along with continuous loss processes in a quantitative model of galactic propagation for cosmic ray protons which is based on stochastic differential equations. We calculated energy spectra at different positions along the Sun's galactic orbit and compared them to the isotropic diffusion case. The results show that a larger amplitude of variation as well as different spectral shapes are obtained in the introduced anisotropic diffusion scenario and emphasize the need for accurate galactic magnetic field models. 
Frederic Effenberger, Horst Fichtner, Klaus Scherer and Ingo   B\"usching
astro-ph.HE