Acceleration of Anomalous Cosmic Rays via Reconnection in the Heliosheath
Abstract
We discuss a model of cosmic ray acceleration that accounts for the observations of anomalous cosmic rays (ACRs) by Voyager 1 and 2. The model appeals to fast magnetic reconnection rather than shocks as the driver of acceleration. The ultimate source of energy is associated with magnetic field reversals that occur in the heliosheath. It is expected that the magnetic field reversals will occur throughout the heliosheath, but especially near the heliopause where the flows slow down and diverge with respect to the interstellar wind and also in the boundary sector in the heliospheric current sheet. While the first-order Fermi acceleration theory within reconnection layers is in its infancy, the predictions do not contradict the available data on ACR spectra measured by the spacecraft. We argue that the Voyager data are one of the first pieces of evidence favoring the acceleration within regions of fast magnetic reconnection, which we believe to be a widely spread astrophysical process. Meridional iew of the boundary of the heliospheric current sheet and how the opposite sectors get tighter closer to the heliopause. There in the presence of turbulence fast reconnection produces first order Fermi acceleration of the anomalous cosmic rays.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSH21A1498L
- Keywords:
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- 7514 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Energetic particles;
- 7807 SPACE PLASMA PHYSICS / Charged particle motion and acceleration;
- 7835 SPACE PLASMA PHYSICS / Magnetic reconnection;
- 7863 SPACE PLASMA PHYSICS / Turbulence