Particle acceleration at reflected shocks in supernova remnants

Abstract

Supernovae remnants (SNRs) are widely considered to be the prime sources of Galactic cosmic rays (CRs). The efficient particle acceleration at the shocks of SNRs is indirectly confirmed by the detection of non-thermal emission across the whole electromagnetic spectrum from radio to very-high-energy gamma-rays. About 80% of all SNRs originate from core-collapse events and are expected to expand into a complex environment of the stellar wind bubble blown up by their progenitor stars, where the forward shock might interact with various density inhomogeneities. Such interactions would cause the formation of reflected shocks propagating back into the remnant which can potentially be strong enough to accelerate particles. Current investigations of particle acceleration in SNRs are usually limited to forward and reverse shocks ignoring the complexity of the hydrodynamic picture. Although for most SNRs the observed shell-like morphology generally agrees with an idea that high energy particles originate predominantly from the forward shock, precise spatially resolved measurements do not always agree with this simplified picture. This work is focused on the investigation of particle acceleration at the reflected shocks formed through the interaction of the forward shock with density inhomogeneities and its potential impact on the overall observational properties.