General relativistic simulations of early jet formation in a rapidly rotating black hole magnetosphere

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. Fire study cases in which the Keplerian accretion disk is both corotating and counterrotating with respect to the black hole rotation, and investigate the first similar to 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.