On the influence of galactic magnetic fields on the arrival direction distribution of ultra-high-energy cosmic rays

Abstract

We study the influence of galactic magnetic field (GMF) on both the correlation between ultra-high-energy cosmic rays (UHECRs) and active galactic nuclei (AGNs) and the clustering of UHECRs in the direction of Centaurus A (Cen A), both of which are observed in the arrival direction distribution of 69 UHECRs with energy E a parts per thousand yen 55 EeV detected by the Pierre Auger Observatory. If UHECRs are dominated by protons, the correlation and the clustering are not affected significantly. However, if UHECRs are dominated by iron nuclei, the influence of the GMF becomes significant, and the correlation and the clustering may be fake due to the GMF while the arrival direction distribution outside of the GMF is compatible with the isotropy.