Cosmic-Ray Acceleration by Forward and Reverse Shocks in Young Supernova Remnants

摘要

Observations of soft gamma-ray spectra from shell-type Supernova Remnants (SNRs) are not in line withstandard Non-linear Diffusive Shock Acceleration (NDSA). We explore alternative ways to explain the observations bymeans of test-particle DSA. The main novelty is the investigation of the impact of the reverse shock in young SNRs using1-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 thatthe reverse shock significantly contributes to the cosmic ray particle population of the SNRs, strongly modifying thespatial distribution of particles and noticeably affecting the volume-integrated particle spectra. Therefore, the spectrumand morphology of emission, and their time evolution, are drastically different from a pure forward-shock solutions. Insome of our models we observed rather soft high-energy gamma-ray spectra, which are well in agreement with currentobservations of Cherenkov telescopes.