Cosmic-Ray Acceleration by Forward and Reverse Shocks in Young Supernova Remnants (original) (raw)

Observations of soft gamma-ray spectra from shell-type Supernova Remnants (SNRs) are not in line with standard Non-linear Diffusive Shock Acceleration (NDSA). We explore alternative ways to explain the observations by means of test-particle DSA. The main novelty is the investigation of the impact of the reverse shock in young SNRs using 1-D simulations of the hydrodynamical evolution and different magnetic field profiles in the shocked material of the SNR. We study the temporal evolution of non-thermal particle distributions and their radiation in a broad domain of energies. We synthesize the surface brightness maps and explore the evolution of their brightness profiles. It is demonstrated that the reverse shock significantly contributes to the cosmic ray particle population of the SNRs, strongly modifying the spatial distribution of particles and noticeably affecting the volume-integrated particle spectra. Therefore, the spectrum and morphology of emission, and their time evolution, are drastically different from a pure forward-shock solutions. In some of our models we observed rather soft high-energy gamma-ray spectra, which are well in agreement with current observations of Cherenkov telescopes.