2006A&A...452..217B

Nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to investigate the properties of Kepler's SNR and, in particular, to predict the γ-ray spectrum expected from this SNR. Observations of the nonthermal radio and X-ray emission spectra as well as theoretical constraints for the total supernova (SN) explosion energy E_sn are used to constrain the astronomical and particle acceleration parameters of the system. Under the assumption that Kepler's SN is a type Ia SN we determine for any given explosion energy E_sn and source distance d the mass density of the ambient interstellar medium (ISM) from a fit to the observed SNR size and expansion speed. This makes it possible to make predictions for the expected γ-ray flux. Exploring the expected distance range we find that for a typical explosion energy E_sn=10⁵¹erg the expected energy flux of TeV γ-rays varies from 2x10^–11 to 10^–13erg/(cm²s) when the distance changes from d=3.4kpc to 7kpc. In all cases the γ-ray emission is dominated by π⁰-decay γ-rays due to nuclear CRs. Therefore Kepler's SNR represents a very promising target for instruments like HESS, CANGAROO and GLAST. A non-detection of γ-rays would mean that the actual source distance is larger than 7kpc.