Sources of sub - GZK cosmic rays

We analyze the existing evidence that BL Lacertae objects (BL Lacs) are sources of the highest-energy cosmic rays. We argue that three independent signatures observed in the real data — (1) improvement of correlations with corrections of trajectories for the Galactic magnetic field; (2) connection between γ-ray and UHECR emissions; (3) non-uniform distribution of correlating rays over the sky — are consistent with the hypothesis that a substantial fraction of cosmic rays in the energy range (4 − 6) × 10 19 eV are protons accelerated in BL Lacs.