Maximal spin and energy conversion efficiency in a symbiotic system of black hole, disk and jet

TL;DR

This paper models the complex interactions in black hole systems to determine how magnetic fields, radiation, and jets influence black hole spin limits and energy efficiency, providing insights for astrophysical observations.

Contribution

It introduces a combined model of black hole, disk, magnetosphere, and jet interactions, revealing how magnetic fields and radiation affect spin limits and efficiency.

Findings

Magnetic fields reduce the spin limit to ~0.89.

Suppression of inner disk radiation increases spin limit.

Collimated jets enhance energy conversion efficiency.

Abstract

We study a combined model of black hole - accretion disk - magnetosphere - jet symbiosis, applicable for supermassive black holes. We quantify the mass and spin evolution and we analyze how the limiting value of the spin parameter and the conversion efficiency of accreted mass into radiation depend on the interplay of electromagnetic radiation reaction, magnetosphere characteristics and truncation radius of radiation. The dominant effect comes from the closed magnetic field line region, which reduces the spin limit to values ~0.89 (instead ~0.99 in its absence). Therefore observations on black hole spins could favour or disfavour the existence of the closed magnetic field line region (or its coupling to the disk). We also find that the suppression of radiation from the innermost part of the accretion disk, inferred from observations, and a collimated jet both increase the spin limit and the energy conversion efficiency.