Abstract
The origin of high energy particles seen radiating in astrophysical synchrotron sources is still a major unresolved problem in high-energy and plasma as trophysics. The diffusive/Fermi shock acceleration under turbulent fields has been discussed as one of important processes in the production of the high-energy particles, but alternative mechanisms that can accelerate particles in a short time scale have been recently discussed as efficient non-thermal particle acceleration mechanisms. First we review the standard diffusive/Fermi acceleration, and then discuss new ideas involving the direct/fast acceleration mechanisms of the magnetic reconnection and the electron shock surfing process.
