The Energetics and Lifetimes of Local Radio Active Galactic Nuclei

TL;DR

This paper models the evolution, energetics, and lifetimes of radio-loud active galactic nuclei, revealing differences between galaxy types and accretion modes, and providing insights into their feedback mechanisms and environmental impacts.

Contribution

It introduces a comprehensive model linking AGN evolution, jet power, and host galaxy properties, with observational validation at low redshift.

Findings

Massive galaxy AGN remain active longer and inject more energy.

Jet power is independent of host stellar mass within uncertainties.

HERGs are younger and have higher jet powers than LERGs.

Abstract

We present a model describing the evolution of Fanaroff-Riley type I and II radio AGN, and the transition between these classes. We quantify galaxy environments using a semi-analytic galaxy formation model, and apply our model to a volume-limited low redshift ($0.03 \leqslant z \leqslant 0.1$) sample of observed AGN to determine the distribution of jet powers and active lifetimes at the present epoch. Radio sources in massive galaxies are found to remain active for longer, spend less time in the quiescent phase, and inject more energy into their hosts than their less massive counterparts. The jet power is independent of the host stellar mass within uncertainties, consistent with maintenance-mode AGN feedback paradigm. The environments of these AGN are in or close to long-term heating-cooling balance. We also examine the properties of high- and low-excitation radio galaxy sub-populations. The HERGs are younger than LERGs by an order of magnitude, whilst their jet powers are greater by a factor of four. The Eddington-scaled accretion rates and jet production efficiencies of these populations are consistent with LERGs being powered by radiatively inefficient advection dominated accretion flows (ADAFs), while HERGs are fed by a radiatively efficient accretion mechanism.