Shock conditions for relativistic MHD jets.
Abstract
The theory of special relativistic magnetohydrodynamic shock waves is analyzed for relativistic jets consisting of a perfect plasma of infinite conductivity. All the postshock physical quantities are expressed in terms of the relativistic compression ratio. This compression ratio is the solution of a polynomial of seventh degree, which has to be solved simultaneously with an equation for the polytropic index for the shocked plasma. The downstream state of the shocked plasma is then determined by the up stream state of the jet as specified by the Lorentz factor, the ratio of the electromagnetic to the material energy content in the jet and the orientation of the magnetic field. These results are applied to the beam cap of relativistic magnetized jets, where the beam shock is mostly perpendicular to the jet direction. We show in particular that already a moderate magnetic field can lead to weak shocks and that for small angles the toroidal component of the magnetic field in the jet will strongly be amplified in the shock transition. We discuss applications of these results for the structure of hot spots in extragalactic radio jets.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 November 1988
 Bibcode:
 1988A&A...206..258A
 Keywords:

 Extragalactic Radio Sources;
 Plasma Jets;
 Radio Jets (Astronomy);
 Relativistic Plasmas;
 Shock Waves;
 Mach Number;
 Magnetic Fields;
 Magnetohydrodynamic Flow;
 Magnetohydrodynamic Stability;
 Particle Acceleration;
 Shock Fronts;
 Astrophysics