Theory of cosmic ray production in the supernova remnant RX J1713.7-3946

Aims. A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is employed to investigate the properties of SNR RX J1713.7-3946. Methods. Observations of the nonthermal radio and X-ray emission spectra as well as the H.E.S.S. measurements of the very high energy γ -ray emission are used to constrain the astronomical and the particle acceleration parameters of the system. Results. Under the assumptions that RX J1713.7-3946 was a core collapse supernova (SN) of type II / Ib with a massive progenitor, has an age of ≈ 1600 yr and is at a distance of ≈ 1 kpc, the theory gives indeed a consistent description for all the existing observational data. Specifically it is shown that an e ffi cient production of nuclear CRs, leading to strong shock modification, and a large downstream magnetic field strength B d ∼ 100 µ G can reproduce in detail the observed synchrotron emission from radio to X-ray frequencies together with the γ -ray spectral characteristics as observed by the H.E.S.S. telescopes. Small-scale filamentary structures observed in nonthermal X-rays provide empirical confirmation for the field amplification scenario which leads to a strong depression of the inverse Compton and Bremsstrahlung fluxes. Going beyond that and using a semi-empirical relation for young SNRs between the resulting CR pressure and the amplified magnetic field energy upstream of the outer SN shock as well as a moderate upper bound for the mechanical explosion energy, it is possible to also demonstrate the actual need for a considerable shock modification in RX J1713.7-3946 . It is consistent with RX J1713.7-3946 being an e ffi cient source of nuclear cosmic rays.