Correlation of ultra-high energy cosmic rays with active galactic nuclei

Abstract

To verify that the active galactic nuclei (AGN) can be the sources of ultra-high energy cosmic rays (UHECR), we constructed three test statistics and tested the hypothesis that AGN are the origin of UHECR using the Monte-Carlo simulation. The observed data from Akeno Giant Air Shower Array (AGASA) and Pierre Auger Observatory (PAO) are used as our UHECR data sets and the AGN list compiled in the 12th edition of Véron-Cetty and Véron (VCV) catalog is used as our AGN data. Only the UHECR with energies above 5.7×1019eV and AGN within Greisen-Zatsepin-Kuzmin (GZK) radius, 100 Mpc, were applied to our statistical tests. We generalized the hypothesis thus it is considered that a certain fraction of the sources is AGN and the rest are isotropic component, coming from the outside of GZK radius. The hypotheses were tested by Kolmogorov-Smirnov (KS) test in two ways, which are the dependence of fraction and that of smearing angles. The probabilities obtained by KS test are extremely small enough to reject the hypotheses that the UHECR come from the AGN within 100 Mpc totally or come from the completely isotropic distribution for the PAO data. In the case of AGASA, it seems there is no significant correlation with AGN. We look forward to solving the problem of the sources of UHECR using the data observed by Telescope Array (TA) experiment.