Large scales anisotropies of extragalactic cosmic rays

D HARARI, S MOLLERACH AND E ROULET

Conferencia; Proceedings, 37th International Conference on High Energy Physics (ICHEP 2014) : Valencia, Spain, July 2-9, 2014; 2014

We discuss the anisotropies at large angular scales expected for extragalactic cosmic rays. The transition from the ?low? energy galactic cosmic rays to the high energy extragalactic ones probably occurs around EeV energies. Depending on the amplitude of the extragalactic magnetic field and the charge of the particles the propagation of extragalactic cosmic rays from their sources to our galaxy would be in the diffusive regime or the quasi-rectilinear one, with just angular diffusion at higher energies. The anisotropy from a single source of protons is obtained using both numerical simulations and analytical approximations. For a diffusive scenario with a few sources in the local supercluster, we discuss the possible transition between the case in which the anisotropies are dominated by a few sources at energies below few EeV towards the regime in which many sources contribute at higher energies. The effect of a non-isotropic source distribution is also discussed, showing that it can significantly affect the observed dipole.