Signatures of black hole spin in galaxy evolution

TL;DR

This paper investigates how black hole spin influences active galactic nucleus (AGN) power, proposing that maximum jet power occurs with highly retrograde black hole spins due to specific magnetic field configurations.

Contribution

It introduces a novel connection between black hole spin orientation and jet power, emphasizing the role of the gap region and gravitomagnetic effects in AGN activity.

Findings

Maximum jet power occurs with highly retrograde black hole spins.

Retrograde spin configurations are energetically excited but unstable.

The gap region plays a crucial role in magnetic field production for jets.

Abstract

We explore the connection between black hole spin and AGN power by addressing the consequences underlying the assumption in the recent literature that the gap region between accretion disks and black holes is fundamental in producing strong, spin-dependent, horizon-threading magnetic fields. Under the additional assumption that jets and outflows in AGN are produced by the Blandford-Znajek and Blandford-Payne mechanisms, we show that maximum jet/outflow power is achieved for accretion onto black holes having highly retrograde spin parameter, an energetically excited yet unstable gravitomagnetic configuration.