Particle Acceleration

It is appropriate that during the centenary of the discovery of cosmic rays by Victor Hess, there should be renewed interest in the acceleration of high energy protons and electrons. This has come from many different sources. New observations of supernova remnants and gamma-ray bursts have vindicated the view that high Mach number external shock waves are efficient accelerators but they have also shown that they amplify magnetic field. There is good evidence that Ultra High Energy (1-100 Joule) cosmic rays exhibit the "GZK" cut off in their spectrum, but their composition is unknown. In addition there is great interest in understanding astrophysical particle acceleration and propagation as this provides the background agains which putative dark matter sources are being sought. I am currently interested in new models of the high Mach number shocks in which magnetic field is amplified far ahead of the shock by firehose instability driven by the escaping highest energy particles. This leads naturally onto a Monte Carlo study of particle transport. New observations of high entropy gas in the outer parts of local, rich clusters of galaxies have re-kindled my interest in cluster accretion shocks as sites of UHE cosmic ray acceleration.

Gamma-ray spectrum of the supernova remnant RX J1713.7-3946 (Abdo et al 2011).

Some Recent Papers

Some Recent Talks