Abstract: The Blandford-Znajek (BZ) mechanism is well known as a mechanism to extract the rotational energy of a black hole with a magnetic field. The power depends on both the magnetic field configuration and the spin parameter of the black hole. The existence of plasma is important for the BZ mechanism, and therefore one should concern both plasma and electromagnetic field around a rotating black hole. Such system becomes highly nonlinear and, because of the difficulty of the nonlinear system, analytical research for the BZ mechanism has been devoted in the case of a slowly rotating black hole. In this talk, we suggest a perturbative method which is useful to obtain the BZ power for a rapidly rotating black hole. In this method, we focus on the case that the magnetic field "corotates" with the black hole. Moreover, we show the spin-dependence of the BZ power obtained by our method in the case that the magnetic field has a monopole configuration.
Place: Physics Dept. Meeting Room, 2th floor, IST