GALACTIC COSMIC-RAY MEDIATION OF A SPHERICAL SOLAR-WIND FLOW .2. THE STEADY-STATE HYDROMAGNETIC APPROXIMATION

In this paper, results from a recently developed energetic particle hydromagnetic model are discussed. Under the assumptions of spherical symmetry and a steady state, the model is applied to the problem of Galactic cosmic-ray mediation of the perpendicular heliospheric termination shock in the equatorial plane. This study clarifies the dynamic role of the heliospheric magnetic field in the presence of Galactic cosmic-ray pressure gradients acting on the solar wind flow. Previous work by others showed that the magnetic field is not dynamically significant within the expected distance to the heliopause, provided that energetic particle dynamic effects on the solar wind flow and termination shock structure are ignored. This paper shows that, if the termination shock is strongly mediated by Galactic cosmic rays, the magnetic field has dynamic consequences for the solar wind even upstream of the termination shock. The resultant spatial dependence of the solar wind velocity downstream of the shock is different from the usual incompressible flow picture. This has consequences for cosmic-ray transport in that region.