The Physics of UHECRs: Spectra, Composition and the Transition Galactic-Extragalactic

Abstract

We review the experimental evidences about flux and mass composition of ultra high energy cosmic rays in connection with theoretical scenarios concerning astrophysical sources. In this context, we also address the discussion about the expected transition between cosmic rays produced inside the Galaxy and those coming from the intergalactic space.Comment: 6 pages, 10 figures, invited talk given at the "2016 International Conference on Ultra-High Energy Cosmic Rays (UHECR2016)", Kyoto (Japan), 11-14 October 2016, version accepted for publication on JPS Conference Proceeding