The Stability of Cosmic-Ray--dominated Shocks: A Secondary Instability
Abstract
Previous studies in one spatial dimension showed that the precursors of cosmic-ray-dominated shocks are unstable against traveling acoustic disturbances. Here we report that a secondary, Rayleigh-Taylor type instability can exist in cosmic-ray-dominated media influenced by the acoustic instability. Using the local WKB approximation, the growth rate of the secondary instability is shown to be comparable to that of the one-dimensional acoustic instability itself in the cases we have considered. The nonlinear development has been followed numerically with a two-dimensional PPM hydrodynamics code that also incorporates the two-fluid cosmic-ray energy equation. We show that the secondary instability may cause the precursor and postshock flows to become highly turbulent.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1993
- DOI:
- 10.1086/172353
- Bibcode:
- 1993ApJ...405..199R
- Keywords:
-
- Acoustic Instability;
- Cosmic Rays;
- Hydrodynamics;
- Shock Waves;
- Shock Wave Propagation;
- Two Dimensional Flow;
- Space Radiation;
- HYDRODYNAMICS;
- INSTABILITIES;
- ISM: COSMIC RAYS;
- SHOCK WAVES