Gamma-ray emitting supernova remnants as the origin of Galactic cosmic rays? |
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| Institution: | 1. Department of Physics, IIT Kanpur, Kanpur 208 016, India;2. Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032, India;1. ISDC, Astronomy Department, University of Geneva, Ch. d’Ecogia 16, Versoix 1290, Switzerland;2. AstroParticle and Cosmology (APC), 10 rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13, France;1. Institut für Experimentelle Kernphysik (IEKP), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany;2. Institut für Kernphysik (IK), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany |
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| Abstract: | The origin of cosmic rays is one of the long-standing mysteries in physics and astrophysics. Simple arguments suggest that a scenario of supernova remnants (SNRs) in the Milky Way as the dominant sources for the cosmic ray population below the knee could work: a generic calculation indicates that these objects can provide the energy budget necessary to explain the observed flux of cosmic rays. However, this argument is based on the assumption that all sources behave in the same way, i.e. they all have the same energy budget, spectral behavior and maximum energy. In this paper, we investigate if a realistic population of SNRs is capable of producing the cosmic ray flux as it is observed below the knee. We use 21 SNRs that are well-studied from radio wavelengths up to gamma-ray energies and derive cosmic ray spectra under the assumption of hadronic emission. The cosmic ray spectra show a large variety in their energy budget, spectral behavior and maximum energy. These sources are assumed to be representative for the total class of SNRs, where we assume that about 100–200 cosmic ray emitting SNRs should be present today. Finally, we use these source spectra to simulate the cosmic ray transport from individual SNRs in the Galaxy with the GALPROP code for cosmic ray propagation. We find that the cosmic ray budget can be matched well for these sources. We conclude that gamma-ray emitting SNRs can be a representative sample of cosmic ray emitting sources. In the future, experiments like CTA and HAWC will help to distinguish hadronic from leptonic sources and to further constrain the maximum energy of the sources and contribute to producing a fully representative sample in order to further investigate the possibility of SNRs being the dominant sources of cosmic rays up to the knee. |
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