Ergomagnetosphere, Ejection Disc, Magnetopause in M87. I Global Flow of Mass, Angular Momentum, Energy and Current

TL;DR

This paper proposes a new model of the M87 black hole environment, suggesting the observed ring is a magnetically-dominated ergomagnetosphere that powers jets and outflows through electromagnetic and MHD processes, extending from the horizon to the Bondi radius.

Contribution

It introduces a novel interpretation of VLBI observations, modeling the black hole's ergomagnetosphere as the source of energy and angular momentum transfer, and describes the global flow of matter and energy in this system.

Findings

The observed ring is a magnetically-dominated ergomagnetosphere.

Energy and angular momentum are transmitted outward via magnetic torque and instabilities.

A large-scale MHD wind collimates jets and drives outflows from the black hole.

Abstract

We interpret the 1.3mm VLBI observations made by the Event Horizon Telescope of the black hole in M87. It is proposed that, instead of being a torus of accreting gas, the observed annular ring is a rotating, magnetically-dominated ergomagnetosphere that can transmit electromagnetic angular momentum and energy outward to the disc through a combination of large scale magnetic torque and small scale instabilities. It is further proposed that energy can be extracted by magnetic flux threading the ergosphere through the efficient emission of long wavelength electromagnetic disturbances onto negative energy orbits, when the invariant $B^2-E^2$ becomes negative. In this way, the spinning black hole and its ergosphere not only power the jets but also the ejection disc so as to drive away most of the gas supplied near the Bondi radius. This outflow takes the form of a MHD wind, extending over many decades of radius, with a unidirectional magnetic field, that is collimated by the infalling gas across a magnetopause. This wind, in turn, collimates the relativistic jets and the emission observed from the jet sheath may be associated with a return current. A model for the global flow of mass, angular momentum, energy and current, on scales from the horizon to the Bondi radius, is presented and discussed.