On the origin of highest energy cosmic rays

A possible mechanism of the acceleration of highest energy cosmic rays is proposed. Mildly relativistic shocks in radio galaxies, especially hot spots in radio lobes, are shown to be able to accelerate protons up to 1020 eV. To avoid energy losses through collisions with radio photons, the size and distance of the acceleration region from the nucleus must be larger than about 100 pc. Required cosmic ray luminosity for each radio galaxy is an order of 1041-42 erg·s-1, which is a modest fraction of the total luminosity. Anisotropy in the arrival direction should be observable towards nearby radio galaxies. (author)