General Relativistic Simulations of Early Jet Formation in a Rapidly Rotating Black Hole Magnetosphere

Abstract

To investigate the formation mechanism of relativistic jets in active galactic nuclei and microquasars, we have developed a new general relativistic magnetohydrodynamic code in Kerr geometry. Here we report on the first numerical simulations of jet formation in a rapidly rotating (a = 0.95) Kerr black hole magnetosphere. We study cases in which the Keplerian accretion disk is both corotating and counter-rotating with respect to the black hole rotation, and investigate the first ~50 light-crossing times. In the corotating disk case, our results are almost the same as those in Schwarzschild black hole cases: a gas pressure-driven jet is formed by a shock in the disk, and a weaker magnetically driven jet is also generated outside the gas pressure-driven jet. On the other hand, in the counter-rotating disk case, a new powerful magnetically driven jet is formed inside the gas pressure-driven jet. The newly found magnetically driven jet in the latter case is accelerated by a strong magnetic field created by frame dragging in the ergosphere. Through this process, the magnetic field extracts the energy of the black hole rotation.