Speaker
John Kirk
Description
Perpendicular shocks are shown to be rapid astrophysical particle
accelerators. They perform optimally when the ratio of
the shock speed to the particle speed roughly equals the ratio
of the scattering rate to the gyro frequency. Analytical methods
and Monte-Carlo simulations are used to solve the
kinetic equation that govern the anisotropy generated at these
shocks, finding a softer spectral
index than the standard result of diffusive shock acceleration, and an
acceleration time significantly shorter than the frequently quoted "Bohm limit".
Amongst other implications, these results provide a theoretical basis for
the thirty-year-old conjecture that a supernova exploding into the
wind of a Wolf-Rayet star may accelerate protons to an energy
exceeding $10^{15}\,$eV.
Primary author
Co-author
Dr
Makoto Takamoto
(Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan)
