Studying cosmic ray propagation in the Galactic magnetic field

The goal of this project is to study the propagation of high energy cosmic ray (CR) nuclei accelerated by Galactic sources, answering the question up to which energy the CR flux at Earth from Galactic sources is still isotropic. Most previous works studyi ng the anisotropy of the CR flux below $10^{19}$ eV used diffusion equations. While this approach is well justified in the fully diffusive regime below energies $\sim Z\times 10^{15}$ eV for nuclei of charge $Z$, it starts to fail at higher energies. On t he other hand, the direct calculation of individual CR trajectories down to energies $\sim Z\times 10^{15}$ eV has become viable, though still demanding, with modern computer power. One of the main improvements in the proposed project compared to earlier works is the use of individual CR trajectories instead of the diffusion approximation. A second major improvement will be the use of recent, more detailed models for the GMF especially for the local neighbourhood of the Sun. As result, we expect to derive reliable upper limits for the Galactic contribution to the overall CR flux as function of energy and the Galactic magnetic field model parameters. In particular, these results may exclude models suggesting a mixed composition. Constraining the compositio n would also be extremely helpful for understanding better the discrepancies between different CR experiments and predictions from QCD models.