Diffusion of cosmic rays in a multiphase interstellar medium swept-up by a supernova remnant blast wave |
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| Institution: | 1. Department of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan;2. Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Osawa, Mitaka District, Tokyo 181-8588, Japan;1. KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm, Sweden;2. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm, Sweden;3. Hiroshima University, Department of Physical Science, Hiroshima 739-8526, Japan;4. Max-Planck-Institut für Physik, D-80805 München, Germany;1. Institute for Nuclear Research, 60th October Anniversary pr. 7A, Moscow 117312, Russia;2. Joint Institute for Nuclear Research, Dubna 141980, Russia;3. Irkutsk State University, Irkutsk 664003, Russia;4. Skobeltsyn Institute of Nuclear Physics MSU, Moscow 119991, Russia;5. Nizhni Novgorod State Technical University, Nizhni Novgorod 603950, Russia;6. St. Petersburg State Marine University, St. Petersburg 190008, Russia;7. EvoLogics GmbH, Berlin, Germany;1. Center for Underground Physics, Institute for Basic science (IBS), Daejeon 305-811, Republic of Korea;2. Department of Physics, Sejong University, Seoul 143-747, Republic of Korea;1. Institute of Nuclear Physics PAN, Kraków, Poland;2. Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology, Karlsruhe, Germany;3. Argelander Institute for Astronomy (AIfA), Bonn, Germany;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. Instituto de Ciência e Tecnologia, Universidade Federal de Alfenas, Rodovia José Aurélio Vilela, 11999, Cidade Universitária, CEP 37715-400, Poços de Caldas, MG, Brazil;2. Escola de Ciência e Tecnologia, Universidade Federal do Rio Grande do Norte, Campus Universitário, s/n, CEP 59072-970, Natal, Brazil |
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| Abstract: | Supernova remnants (SNRs) are one of the most energetic astrophysical events and are thought to be the dominant source of Galactic cosmic rays (CRs). A recent report on observations from the Fermi satellite has shown a signature of pion decay in the gamma-ray spectra of SNRs. This provides strong evidence that high-energy protons are accelerated in SNRs. The actual gamma-ray emission from pion decay should depend on the diffusion of CRs in the interstellar medium. In order to quantitatively analyse the diffusion of high-energy CRs from acceleration sites, we have performed test particle numerical simulations of CR protons using a three-dimensional magnetohydrodynamics (MHD) simulation of an interstellar medium swept-up by a blast wave. We analyse the diffusion of CRs at a length scale of order a few pc in our simulated SNR, and find the diffusion of CRs is precisely described by a Bohm diffusion, which is required for efficient acceleration at least for particles with energies above 30 TeV for a realistic interstellar medium. Although we find the possibility of a superdiffusive process (travel distance ∝ t0.75) in our simulations, its effect on CR diffusion at the length scale of the turbulence in the SNR is limited. |
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