Combined STEREO/RHESSI study of CME acceleration and particle acceleration in solar flares

TL;DR

This study combines STEREO and RHESSI data to analyze the acceleration of three fast CMEs and their associated high-energy flares, revealing synchronized evolution supporting the standard flare/CME model.

Contribution

It introduces a new regularization-based algorithm for high-cadence CME kinematic measurements and demonstrates the synchronized evolution of CME acceleration and flare energy release.

Findings

CME maximum acceleration occurs below 0.4 Rs

Peak velocity is reached below 2.1 Rs, sometimes as low as 0.5 Rs

CME acceleration and flare energy release evolve synchronously

Abstract

Using the potential of two unprecedented missions, STEREO and RHESSI, we study three well observed fast CMEs that occurred close to the limb together with their associated high energy flare emissions in terms of RHESSI HXR spectra and flux evolution. From STEREO/EUVI and STEREO/COR1 data the full CME kinematics of the impulsive acceleration phase up to 4 Rs is measured with a high time cadence of less equal 2.5 min. For deriving CME velocity and acceleration we apply and test a new algorithm based on regularization methods. The CME maximum acceleration is achieved at heights h < 0.4 Rs, the peak velocity at h < 2.1 Rs (in one case as small as 0.5 Rs). We find that the CME acceleration profile and the flare energy release as evidenced in the RHESSI hard X-ray flux evolve in a synchronized manner. These results support the standard flare/CME model which is characterized by a feed-back relationship between the large-scale CME acceleration process and the energy release in the associated flare.