Broken Power-law Distributions from Low Coronal Compression Regions or Shocks

Coronal Mass Ejection (CME) expansion regions low in the corona (< 2 - 3 R-s) are highly efficient for the acceleration of energetic particles. Because the acceleration occurs over a finite spatial region, there is a regime where particles diffuse away and escape from the acceleration sites, leading to the formation of broken power-law distributions. This paper highlights recent results indicating that CME expansion and acceleration in the low corona may cause rapid particle acceleration and create large solar energetic particle events with broken power-law distributions.