Ultra–High‐Energy Cosmic Rays and the Large‐Scale Structure of the Galactic Magnetic Field

Abstract

We study the deflection of ultra--high-energy cosmic-ray protons in different models of the regular Galactic magnetic field. Such particles have gyroradii well in excess of 1 kpc and their propagation in the Galaxy is not affected by the small-scale structure of the field. Their trajectories, however, reflect the large-scale structure. A future large experimental statistics of cosmic rays of energy above 1019 eV could be used for a study of the large-scale structure of the Galactic magnetic field if such cosmic rays are indeed charged nuclei accelerated at powerful astrophysical objects and if the distribution of their sources is not fully isotropic. We also show the corrections of the arrival directions resulting from the deflection in the Galactic magnetic field of a subsample of the world statistics of cosmic rays of energy above 2 x 1019 eV and discuss the implications for the search for the sources of these events.