Cosmic-ray composition and its relation to shock acceleration by supernova remnants.pdfVIP

Cosmic-ray composition and its relation to shock acceleration by supernova remnants ⋆ J¨org R. H¨orandel University of Karlsruhe, Institute for Experimental Nuclear Physics, P.O. Box 3640, 76021 Karlsruhe, Germany 7 0 Abstract 0 2 An overview is given on the present status of the understanding of the origin of galactic cosmic rays. Recent measurements of charged cosmic rays and photons are reviewed. Their impact on the contemporary knowledge about the sources and acceleration n u mechanisms of cosmic rays and their propagation through the Galaxy is discussed. Possible reasons for the knee in the energy J spectrum and scenarios for the end of the galactic cosmic-ray component are described. 5 Key words: cosmic rays, origin, acceleration, propagation, knee, air shower 2 PACS: 98.70.Sa, 96.50.sd v 0 7 3 1. Introduction the mean mass, and spectra for individual elements are 2 compiled and their impact on the contemporary knowledge 0 7 The origin of high-energy cosmic rays is one of the open of the origin of galactic cosmic rays is discussed. The end of 0 questions in astroparticle physics. The fully ionized atomic the galactic cosmic-ray spectrum and the transition to an / nuclei reach the Earth from outside the solar system with extragalactic component is briefly illuminated in Sect. 6. h penergies from the GeV range up to 1020 eV. Most of them - are assumed to originate in the Milky Way. At the high- 2. Experimental Techniques o 17 r est energies, exceeding 10 eV, the particles are usually t considered of extragalactic origin. This review focuses on The energies of cosmic r