3D Relativistic Magnetohydrodynamic Simulations of Magnetized Spine-Sheath Relativistic Jets

Numerical simulations of weakly magnetized and strongly magnetized relativistic jets embedded in a weakly magnetized and strongly magnetized stationary or weakly relativistic (v = c/2) sheath have been performed. A magnetic field parallel to the flow is used in these simulations performed by the new GRMHD numerical code RAISHIN used in its RMHD configuration. In the numerical simulations the Lorentz factor γ = 2.5 jet is precessed to break the initial equilibrium configuration. In the simulations sound speeds are . c/ √ 3 in the weakly magnetized simulations and . 0.3 c in the strongly magnetized simulations. The Alfvén wave speed is . 0.07 c in the weakly magnetized simulations and . 0.56 c in the strongly magnetized simulations. The results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized relativistic magnetohydrodynamic (RMHD) equations capable of describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized relativistically moving sheath. The theoretical dispersion relation allows investigation of effects associated with maximum possible sound speeds, Alfvén wave speeds near light speed and relativistic sheath speeds. The prediction of increased stability of the weakly magnetized system resulting from c/2 sheath speeds and the stabilization of the strongly magnetized system resulting from c/2 sheath speeds is verified by the numerical simulation results. Subject headings: galaxies: jets — gamma rays: bursts — ISM: jets and outflows — methods: analytical — MHD — relativity — instabilities National Space Science and Technology Center, 320 Sparkman Drive, VP 62, Huntsville, AL 35805, USA; [email protected] Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL 35487, USA Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville , Huntsville, AL 35899, USA NASA Postdoctoral Program Fellow/ NASA Marshall Space Flight Center