Ultra-high energy cosmic rays with the Pierre Auger Observatory

Abstract

In the era of multi-messenger astronomy, ultra-high energy cosmic rays offer the unique opportunity to investigate the nature of astrophysical sources and of particle interactions in an energy range far beyond that covered by current particle accelerators. The Pierre Auger Observatory, the world’s largest cosmic ray detector, combines in a hybrid design the information from fluorescence telescopes, observing the longitudinal profile of extensive air showers, with a surface array, measuring the lateral distributions of secondary particles at the ground. A review of selected results is presented, focusing on the measurements of energy spectrum and chemical composition and on the search for neutral primary particles. The future prospects will also be discussed in light of the extensive upgrade program being now implemented to further improve the Observatory potential.