Energy Extraction of Rotating Black Hole by Magnetic Reconnection

Shinji Koide

Kumamoto University, Japan

Abstract:
We review mechanisms of energy extraction from a rotating
black hole in terms of negative energy-at-infinity. Especially, we
examine energy extraction from a black hole caused by magnetic
reconnection in the ergosphere. The reconnection redistributes the
angular momentum efficiently to induce the negative energy-at-infinity
like particle fission of the Penrose process. We derive a condition
for the process to operate in a simple situation, where the plasma is
incompressible and the magnetic energy is converted completely to the
plasma kinetic energy locally. It shows that relativistic magnetic
reconnection is required to induce the negative energy-at-infinity.
To calculate the relativistic magnetic reconnection, we have to use
resistive relativistic MHD (resistive RMHD), because the magnetic
reconnection is caused by local electric resistivity at a X-point. We
also show the causality problem of the standard resistive RMHD and
propose a set of generalized RMHD to fix it.