The interaction of alfvén waves with perpendicular shocks

Abstract

Two-dimensional hybrid simulations are performed to investigate the interaction of Alfvén waves with a perpendicular shock self-consistently. The perpendicular shock is formed by reflecting the particles in the right boundary, and it propagates to the left. The Alfvén waves are injected from the left boundary, and they are convected toward the right. The results show that the injected Alfvén waves have no obvious effects on the propagation speed of the shock. However, after the upstream Alfvén waves are transmitted into the downstream, their amplitude is enhanced about 10-30 times. The transmitted waves can be separated into two parts, and both of them are left-hand polarized Alfvén waves: one propagates along the +y direction and the other along the -y direction. Obvious ripples in the shock front are also found due to the interaction of the Alfvén waves with the shock. The great enhancement of the amplitude of the Alfvén waves by the shock is verified by the satellite observations. The implications of the simulation results to the influences on the diffusive shock acceleration are also discussed in this paper. © 2009. The American Astronomical Society. All rights reserved.