Electromagnetic wave emission during collision between a current sheet and a fast magnetosonic shock associated with coronal mass ejections

Abstract

Aims. We investigate how the emission of electromagnetic waves can be enhanced when a fast magnetosonic shock wave associated with a coronal mass ejection (CME) collides perpendicularly to a coronal streamer with a stable current sheet. Methods. A two-dimensional relativistic and fully electromagnetic Particle-In-Cell (PIC) code is used. Results. It is shown that the ions in front of the shock can be accelerated by the surfatron acceleration mechanism. This shock compresses the current sheet, resulting in a local electron temperature anisotropy. The electron Bernstein waves are generated by the local electron temperature anisotropy and they are converted into electromagnetic waves (X-mode) through the linear mode conversion due to density inhomogeneity. As a result, the electromagnetic waves are observed in both forward and backward regions of the shock. The simulation results may be applied to the enhancement of electromagnetic wave emissions when a shock wave associated with CMEs collides with a coronal streamer.