Isotropy of cosmic rays caused by magnetic discontinuities.
Abstract
When cosmic rays stream past a bend in a magnetic field, they acquire a correlation in their phase of gyration about the magnetic field. The resulting plasma instability generates Alfven waves and simultaneously reduces the cosmic rays' mean streaming velocity along the field. The growth rate of the instability is proportional to a fractional power of the cosmic-ray density and is rapid even for cosmic rays above 10 to the 11th power eV. A few interstellar shocks or interplanetary rotational discontinuities suffice to reduce the streaming anisotropy to the local Alfven velocity. Cosmic rays of 10 to the 11th power eV may be made nearly isotropic even within the solar system.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1977
- DOI:
- 10.1086/182509
- Bibcode:
- 1977ApJ...216L..59W
- Keywords:
-
- Cosmic Rays;
- Interplanetary Magnetic Fields;
- Magnetohydrodynamic Stability;
- Radiation Distribution;
- Gyration;
- Isotropy;
- Magnetohydrodynamic Waves;
- Particle Flux Density;
- Propagation Velocity;
- Shock Wave Propagation;
- Space Radiation