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Title: PARTICLE ACCELERATION AT LOW CORONAL COMPRESSION REGIONS AND SHOCKS

We present a study on particle acceleration in the low corona associated with the expansion and acceleration of coronal mass ejections (CMEs). Because CME expansion regions low in the corona are effective accelerators over a finite spatial region, we show that there is a rigidity regime where particles effectively diffuse away and escape from the acceleration sites using analytic solutions to the Parker transport equation. This leads to the formation of broken power-law distributions. Based on our analytic solutions, we find a natural ordering of the break energy and second power-law slope (above the break energy) as a function of the scattering characteristics. These relations provide testable predictions for the particle acceleration from low in the corona. Our initial analysis of solar energetic particle observations suggests a range of shock compression ratios and rigidity dependencies that give rise to the solar energetic particle (SEP) events studied. The wide range of characteristics inferred suggests competing mechanisms at work in SEP acceleration. Thus, CME expansion and acceleration in the low corona may naturally give rise to rapid particle acceleration and broken power-law distributions in large SEP events.
Authors:
; ; ; ;  [1] ;  [2] ; ; ; ; ; ;  [3] ; ; ;  [4] ;  [5]
  1. University of New Hampshire, Durham, NH 03824 (United States)
  2. Southwest Research Institute, San Antonio, TX 78238 (United States)
  3. Predictive Science Inc., San Diego, CA 92121 (United States)
  4. University of Arizona, Tucson, AZ 85721 (United States)
  5. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22525461
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 810; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ANALYTICAL SOLUTION; COMPRESSION; COMPRESSION RATIO; EXPANSION; MASS; SCATTERING; SOLAR CORONA; SOLAR PARTICLES; SUN; TRANSPORT THEORY