Density jump as a function of magnetic field strength for parallel collisionless shocks with anisotropic upstream pressure

Abstract

The properties of collisionless shocks are frequently assessed in the magnetohydrodynamics (MHD) model. Yet, in a collisionless plasma, an ambient magnetic field can sustain a stable anisotropy in the upstream or the downstream, resulting in a departure from the MHD predicted behavior. We present a model allowing to derive the downstream anisotropy, hence the shock density jump, in terms of the upstream quantities. For simplicity, the case of a parallel shock in pair plasma is considered. Contrary to previous works where the upstream was assumed isotropic, here the upstream anisotropy $A=T_{\perp }/T_{\parallel }$ is a free parameter. The strong sonic shock regime is formally identical to the isotropic upstream case. Yet, for intermediate sonic Mach numbers, a variety of behaviors appear as a result of the anisotropy of the upstream.

To appear in MNRAS, 8 pages, 6 figures

References in corpus (7)

• The Physical Mechanisms of Fast Radio Bursts
• Coherent Electromagnetic Emission from Relativistic Magnetized Shocks
• Electron Heating in Low Mach Number Perpendicular shocks. I. Heating Mechanism
• Density jump as a function of magnetic field for collisionless shocks in pair plasmas: the perpendicular case
• In-situ Measurement of the Energy Fraction in Supra-thermal and Energetic Particles at ACE, Wind, and PSP Interplanetary Shocks
• Bi-directional streaming of particles accelerated at the STEREO-A shock on 9th March 2008
• Modified jump conditions for parallel collisionless shocks