Jump conditions for pressure anisotropy and comparison with the Earth's bow shock
- 1Space Research Institute, Austrian Academy of Sciences, Graz, Austria
- 2also at: Institute for Geophysics, Astrophysics, and Meteorology, University of Graz, Austria
- 3also at: Institute for Theoretical Physics, University of Graz, Austria
- 4Institute of Computational Modelling, Russian Academy of Sciences, Krasnoyarsk, Russia
- 5Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, USA
Abstract. Taking into account the pressure anisotropy in the solar wind, we study the magnetic field and plasma parameters downstream of a fast shock, as functions of upstream parameters and downstream pressure anisotropy. In our theoretical approach, we model two cases: a) the perpendicular shock and b) the oblique shock. We use two threshold conditions of plasma instabilities as additional equations to bound the range of pressure anisotropy. The criterion of the mirror instability is used for pressure anisotropy p \perp /p\parrallel > 1. Analogously, the criterion of the fire-hose instability is taken into account for pressure anisotropy p \perp /p\parrallel < 1. We found that the variations of the parallel pressure, the parallel temperature, and the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock. Finally, we compare our theory with plasma and magnetic field parameters measured by the WIND spacecraft.