I review some basic properties of diffusive shock acceleration (DSA) in the context of young supernova remnants (SNRs). I also point out some key differences with cosmological, cluster-related shocks. DSA seems to be very efficient in strong, young SNR shocks. Provided the magnetic fields exceed some hundreds of μGauss (possibly amplified by CR related dynamics), these shocks can accelerate cosmic ray hadrons to PeV energies in the time available to them. Electron energies, limited by radiative losses, are likely limited to the TeV range. Injection of fresh particles at these shocks is poorly understood, but hadrons are much more easily injected than the more highly magnetized electrons. That seems supported by observational data, as well. So, while CR protons in young SNRs may play very major roles in the SNR evolution, the CR electron populations have minimal such impact, despite their observational importance.
Bibliographical noteFunding Information:
I am very grateful to the organizers for the invitation and opportunity to participate in this excellent workshop. This work is supported by NASA grant NNX09AH78G and US NSF grant AST0908668. Figure 1 is an adaptation of a figure originally prepared by Hyesung Kang.
- Particle acceleration
- galaxy cluster shocks
- supernova remnant shocks