A Simplified Model of ADAF with the Jet Driven by the Large-Scale Magnetic Field

TL;DR

This paper introduces a simplified model of outflows and jets driven by magnetic fields in ADAFs, explaining observed correlations in AGNs and the FR I/II galaxy dichotomy through accretion physics.

Contribution

It presents a new simplified analytical model of jet power from ADAFs and reinterprets the FR I/II dichotomy based on accretion rates and magnetic fields.

Findings

Anti-correlation between accretion rate and advection parameter.

FR I/II dichotomy mainly depends on accretion rate, not black hole mass.

FR I sources are predominantly in the ADAF state.

Abstract

We propose a simplified model of outflow/jet driven by the Blandford-Payne (BP) process from advection dominated accretion flows (ADAF) and derive the expressions of the BP power and disk luminosity based on the conservation laws of mass, angular momentum and energy. We fit the 2--10 keV luminosity and kinetic power of 15 active galactic nucleus (AGNs) of sub-Eddington luminosity. It is found that there exists an anti-correlation between the accretion rate and the advection parameter, which could be used to explain the correlation between Eddington-scaled kinetic power and bolometric luminosity of the 15 samples. In addition, the Ledlow-Owen relation for FR I/II dichotomy is re-expressed in a parameter space consisting of logarithm of dimensionless accretion rate versus that of the BH mass. It turns out that the FR I/II dichotomy is determined mainly by the dimensionless accretion rate, being insensitive to the BH mass. And the dividing accretion rate is less than the critical accretion rate for ADAFs, suggesting that FR I sources are all in the ADAF state.