The origin of cosmic rays of extreme energy remains unknown. The data collected over the past few decades by the Pierre Auger Observatory and the Telescope Array indicate the presence of anisotropy in the distribution of their arrival directions, suggesting extragalactic astrophysical sources. However, the nature of these sources is still unsolved. The interaction with the CMB during propagation limits the origin of these particles to nearby sources (GZK effect). We investigate here the anisotropy of ultra-high-energy (UHE) cosmic rays (≳ 1018 eV) for two prominent classes of nearby extragalactic objects: starburst galaxies (SBG) and active galactic nuclei (AGN). These astrophysical objects provide the energy budget required to produce the observed flux of UHE cosmic rays and meet Hillas criterion.
Reda Attallah (Thu,) studied this question.