Relativistic MHD Simulations of Relativistic Jets

Relativistic jets have been observed or postulated in various astrophysical sources, including active galactic nuclei (AGNs), microquasars in the galaxy and gamma-ray bursts (GRBs). There are four major problems related to the relativistic jets: 1. formation mechanism, 2. acceleration mechanism, 3. collimation mechanism, and 4. long-term stability. The most promising mechanisms for producing and accelerating relativistic jets, and maintaining collimated structure of relativistic jets involve magnetohydrodynamical processes.

We perform 2D general relativistic MHD simulations involving a geometrically thin accretion disk near both non-rotating and rotating black holes by using newly-developed 3D GRMHD code ``RAISHIN''. In the rotating black hole case an inner jet forms near the black hole region in the magnetic field strongly twisted by frame-dragging. This inner jet/spine lies within an outer jet/sheath produced by the magnetic fields anchored accretion disk. When the jet propagates, such a jet/spine and sheath/wind configuration considerably modifies the stability properties and potential structure of the jet resulting from spine-sheath interaction. We have performed 3D relativistic MHD simulations to study the Kelvin-Helmholtz (KH) instability of magnetized spine-sheath relativistic jets. We found that the growth of the KH instability is reduced significantly by a mildly relativistic sheath flow and can be stabilized by a magnetized sheath flow.

Dr. Y. Mizuno

MSFC/NSSTC