Outgoing electromagnetic power induced from pair plasma falling into a rotating black hole

TL;DR

This paper investigates how energy from pair plasma accreting onto a rotating black hole can be converted into outgoing electromagnetic power, highlighting differences from the Blandford-Znajek process.

Contribution

It introduces a two-fluid model showing how electric and magnetic fields are generated by black hole rotation, differing from ideal MHD assumptions.

Findings

Electromagnetic power peaks near the black hole

Power is comparable to Blandford-Znajek process

Electric fields are generated by rotation in the plasma

Abstract

We examine energy conversion from accreting pair plasma to outgoing Poynting flux by black hole rotation. Our approach is based on a two-fluid model consisting of collisionless pair plasma. The electric potential is not constant along magnetic field lines, unlike an ideal magnetohydrodynamics approximation. We show how and where longitudinal electric fields and toroidal magnetic fields are generated by the rotation, whereas they vanish everywhere for radial flow in a split monopole magnetic field in a Schwarzschild black hole. Outgoing electromagnetic power in a steady state is calculated by applying the WKB method to the perturbation equations for a small spin parameter. In our model, the luminosity has a peak in the vicinity of the black hole, but is damped toward the event horizon and infinity. The power at the peak is of the same order as that in the Blandford--Znajek process, although the physical mechanism is different.