Black hole mass, jet power and accretion in AGN

TL;DR

This study investigates the relationships between black hole mass, accretion, and jet power in AGN, revealing different regimes and mechanisms, and supporting the unified model of AGN through analysis of a large sample of blazars and radio galaxies.

Contribution

It provides new insights into the dependence of jet power on black hole mass and accretion mode, and challenges the sufficiency of the Blandford-Znajek mechanism for explaining jet power.

Findings

Jet power depends on black hole mass or accretion mode depending on AGN type.

Most AGN have jet power exceeding the maximum predicted by the Blandford-Znajek mechanism.

Distinct accretion modes and a bimodal distribution of Eddington ratios support different AGN subclasses.

Abstract

We study the relation between accretion, black hole mass and jet power in AGN, by using a large group of blazars detected by the Fermi Large Area Telescope and radio galaxies. Our main results are as follows. (i) The jet power of FSRQs and FRII-HEG depends on the black hole mass, which suggests that the FSRQs and FRII-HEG are in Radiation-Pressure Dominated regime. The jet power of BL Lacs and FRI-LEG depends on the accretion, which suggests that the BL Lacs and FRI-LEG are in the Gas-Pressure Dominated regime. (ii) We find that most of FSRQs and BL Lacs have $\rm{P_{jet}>L_{BZ}^{max}}$, which suggests that the Blandford-Znajek mechanism is insufficient to explain the jet power of these objects. (iii) The FSRQs are roughly separated from BL Lacs by the Ledlow-Owen's dividing line in the $\rm{\log P_{jet}-\log M}$ plane, which supports the unified scheme of AGN. (iv) The FSRQs and BL Lacs have a clear division at $\rm{L_{bol}/L_{Edd}\sim0.01}$, and the distribution of Eddington ratios of BL Lacs and FSRQs exhibits a bimodal nature, which imply that the accretion mode of FSRQs may be different from that of BL Lacs. (v) We find a significant correlation between broad line luminosity and jet power, which supports a direct tight connection between jet power and accretion.