Oral Presentation

Causal production of the electromagnetic energy flux in Blandford-Znajek process

Author(s): Kenji Toma (Tohoku University) and Fumio Takahara (Osaka University)

Presenter: Kenji Toma (Tohoku University)

Blandford-Znajek process is widely believed to work for driving relativistic jets in active galactic nuclei, although it is still under debate how the Poynting flux is causally produced and how the rotational energy of the black hole (BH) is reduced. We consider that neither the membrane paradigm nor the steady inflow of the negative electromagnetic energy is convincing. We generally discuss the Kerr BH magnetosphere filled with a collisionless plasma screening the electric field along the magnetic field, extending the arguments of Komissarov and our previous paper, and propose a new picture. We argue that the issues cannot be resolved by investigating only the steady-state structure, and build an analytical toy model of a time-dependent process of building the poloidal current structure in the Boyer-Lindquist and Kerr-Schild coordinate systems. In the steady state, the Poynting flux is maintained without any electromagnetic source, and it directly reduces the BH rotational energy without being mediated by any infalling negative-energy objects.