A magnetohydrodynamic boost for relativistic jets

Abstract

We performed relativistic magnetohydrodynamic simulations using the RAISHIN code of the hydrodynamic boosting mechanism for relativistic jets explored by Aloy and Rezzolla. Simulation results show that the presence of a magnetic field changes the properties of the shock interface between a tenuous, overpressured jet flowing parallel to the shock interface and a dense external medium. Magnetic fields can lead to more efficient acceleration of the jet, in comparison to the pure-hydrodynamic case. A poloidal magnetic field (B ^z), tangent to the interface and parallel to the jet flow, produces both a stronger outward moving shock and a stronger inward moving rarefaction wave. This leads to a large velocity component normal to the interface in addition to acceleration tangent to the interface, and the jet is thus accelerated to larger Lorentz factors than those obtained in the pure hydrodynamic case. Likewise, a strong toroidal magnetic field (B^y), tangent to the interface but perpendicular to the jet flow, also leads to stronger acceleration tangent to the shock interface relative to the pure hydrodynamic case. Thus, the presence and relative orientation of a magnetic field in relativistic jets can significant modify the hydrodynamic boost mechanism studied by Aloy and Rezzolla. © 2008 American Institute of Physics.