A Scheme to Unify Low-Power Accreting Black Holes - Jet-Dominated Accretion Flows and the Radio/X-Ray Correlation

TL;DR

This paper proposes a unified model for low-power accreting black holes, linking jet-dominated emission and radio/X-ray correlations across different black hole systems and states.

Contribution

It introduces a state transition scheme based on accretion rate, unifying various black hole systems through a common jet-dominated emission model and scaling relations.

Findings

Jet-dominated emission explains spectral energy distributions in sub-Eddington systems.

Radio/X-ray correlation is unified across different black hole types.

Scaling relations depend on black hole mass and Doppler factor.

Abstract

We explore the evolution in power of black holes of all masses, and their associated jets, within the scheme of an accretion rate-dependent state transition. Below a critical value of the accretion rate all systems are assumed to undergo a transition to a state where the dominant accretion mode is optically thin and radiatively inefficient. In these significantly sub-Eddington systems, the spectral energy distribution is predicted to be dominated by non-thermal emission from a relativistic jet whereas near-Eddington black holes will be dominated instead by emission from the accretion disk. Reasonable candidates for such a sub-Eddington state include X-ray binaries in the hard and quiescent states, the Galactic Center (Sgr A*), LINERs, FR I radio galaxies, and a large fraction of BL Lac objects. Standard jet physics predicts non-linear scaling between the optically thick (radio) and optically thin (optical or X-ray) emission of these systems, which has been confirmed recently in X-ray binaries. We show that this scaling relation is also a function of black hole mass and only slightly of the relativistic Doppler factor. Taking the scaling into account we show that indeed hard and quiescent state X-ray binaries, LINERs, FR I radio galaxies, and BL Lacs can be unified and fall on a common radio/X-ray correlation. This suggests that jet domination is an important stage in the luminosity evolution of accreting black hole systems.