Acceleration of electrons by interacting CMEs

Abstract

There is growing observational evidence that interaction of coronal mass ejections (CMEs) near the Sun is a common phenomenon, particularly during the solar cycle's maximum years. Recently, we performed 2.5-D MHD simulations of the interaction between two magnetic flux ropes. The aim was to provide some qualitative picture of the shock-cloud and cloud-cloud dynamic interactions that might be relevant to the interaction of CMEs. A sufficiently fast CME generates a shock wave that penetrates a slower CME. Enhanced magnetic field magnitudes in the flux rope and helical structure may favor acceleration of electrons at the shock by the fast-Fermi process since multiple encounters are possible and nearly perpendicular parts of the shock are more abundant. Using results of our MHD simulations, we numerically examine the efficiency of electron acceleration during the CME's interaction.