SEP acceleration in CME driven shocks using a hybrid code

TL;DR

This study uses hybrid simulations to analyze shock acceleration driven by CMEs in the solar wind, revealing wave generation and two-phase particle acceleration consistent with Fermi mechanisms.

Contribution

It presents a self-consistent hybrid simulation approach to study CME-driven shock propagation and particle acceleration in the solar wind.

Findings

Electromagnetic Alfven waves are generated at the shock front.

Particles are accelerated in two phases: upstream drift and shock trapping.

A fraction of particles diffuse back to the shock, supporting Fermi acceleration.

Abstract

We preform hybrid simulations of super Alfvenic quasi-parallel shock, driven by a Coronal Mass Ejection (CME), propagating in the Outer Coronal or Solar Wind at distances of between 3 to 6 solar radii. The hybrid treatment of the problem enable the study of the shock propagation on the ion time scale, preserving ion kinetics and allowing for a self consistent treatment of the shock propagation and particle acceleration. The CME plasma drags the embedded magnetic field lines stretching from the sun, and propagates out into interplanetary space at a greater velocity than the in-situ solar wind, driving the shock, and producing very energetic particles. Our results show electromagnetic Alfven waves are generated at the shock front. The waves propagate upstream of the shock and are produced by the counter streaming ions of the solar wind plasma being reflected at the shock. A significant fraction of the particles are accelerated in two distinct phases: first, particles drift from the shock and are accelerated in the upstream region and, second, particles arriving at the shock get trapped, and are accelerated at the shock front. A fraction of the particles diffused back to the shock, which is consistent with the Fermi acceleration mechanism.