Black Hole Aurora powered by a Rotating Black Hole

TL;DR

This paper proposes a model where high-energy emissions near a rotating black hole are generated by MHD shocks in the black hole's magnetosphere, potentially explaining phenomena like AGN and gamma-ray bursts.

Contribution

It introduces a novel model linking MHD shocks in black hole magnetospheres to high-energy emissions, highlighting energy extraction from black hole rotation.

Findings

Demonstrates large energy output at shock fronts near black holes.

Shows energy extraction from black hole rotation can power radiative emissions.

Predicts a ring-shaped hot plasma region resembling an aurora.

Abstract

We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and hole's rotational energy can convert to radiative energy. In this letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; the look would be like an "aurora". The high energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.