Astron. Astrophys. 332, 385-390 (1998)

Acoustic emission and corrugational instability of shocks modified by strong particle acceleration

M. Mond ^* and L. O'C. Drury

Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland

Received 20 September 1997 / Accepted 11 December 1997

Abstract

The effect of particles that undergo strong diffusive-shock-acceleration on the stability of the accelerating shock is investigated. A two-fluid model is employed in which the accelerated particles are treated as a fluid whose effect is incorporated as an additional pressure in the momentum equation. The Dyakov and Kontorovich stability criteria are used in order to study the stability of those steady-state shocks that contain a gas sub-shock. The downstream conditions of the latter are parametrized by the ratio of the upstream acclerated-particles pressure to the total pressure. For some range of values of that parameter, three possible downstream states are possible for each upstream state. It is shown that in that range of parameters the shocks are either corrugationally unstable or lose their energy by spontaneous emission of acoustic as well as entropy-vortex waves.

Key words: acceleration of particles instabilities shock waves

* Permanent address: The Pearlstone Center for Aeronautical Engineering Studies, Department of Mechanical Engineering, Ben-Gurion University, Beer-Sheva, Israel

Contents

• 1. Introduction
• 2. The two-fluid model
• 3. Stability criteria for shocks
• 4. Stability of shocks modified by particle acceleration
  • 4.1. The Hugoniot curve
  • 4.2. The stability analysis
• 5. The effect of particle diffusion
• 6. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: March 10, 1998
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