Ratio of kinetic luminosity of the jet to bolometric luminosity of the disk at the "cold" accretion onto a supermassive black hole

TL;DR

This paper investigates the ratio of jet kinetic luminosity to disk bolometric luminosity in cold accretion onto supermassive black holes, deriving equations that align with observations of M87 and predict fluxes for Sgr A*.

Contribution

It provides a theoretical framework linking magnetic field pressures to jet and disk luminosity ratios in cold accretion models.

Findings

The ratio is mainly determined by magnetic field pressure ratios.

Equations match observed jet luminosity in M87.

Predictions for Sgr A*'s jet flux are consistent with models.

Abstract

Disk accretion onto black holes is accompanied by collimated outflows (jets). In active galactic nuclei (AGN), the kinetic energy flux of the jet may exceed the bolometric luminosity of the disk a few orders of magnitude. This phenomena can be explained in frameworks of so called "cold" disk accretion when the only source of energy of AGN is the energy released at the accretion. The radiation from the disk is suppressed because the wind from the disk carries out almost all the angular momentum and the gravitational energy of the accreted material. In this paper, we calculate an unavoidable radiation from the "cold" disk and the ratio of the kinetic energy luminosity of the outflow to the bolometric luminosity of the accretion disk around a super massive black hole in framework of the paradigm of the optically thick alpha-disk of Shakura \& Sunyaev. The ratio of the luminosities is defined predominantly by the ratio of the magnetic field pressure inside the disk to the magnetic field pressure at the base of the wind. The obtained equations applied to the jet of M87 demonstrate good agreement with observations. In the case of Sgr A*, these equations allow us to predict the kinetic energy flux from the disk around Galactic SMBH.