The duty cycle of local radio galaxies

TL;DR

This study investigates the duration and recurrence of radio-active and quiescent phases in local galaxies, revealing dependencies on stellar mass and fueling processes, and distinguishing between radio and emission line AGN activity.

Contribution

It provides new insights into the duty cycle of radio galaxies, showing how active phases depend on stellar mass and are linked to gas cooling and fuel depletion.

Findings

Active phase duration depends on stellar mass.

More massive hosts experience more frequent retriggering.

Radio and emission line AGN activities are independent.

Abstract

We use a volume- and flux-limited sample of local ($0.03 \leq z \leq 0.1$) radio galaxies with optical counterparts to address the question of how long a typical galaxy spends in radio-active and quiescent states. The length of the active phase has a strong dependence on the stellar mass of the host galaxy. Radio sources in the most massive hosts are also retriggered more frequently. The time spent in the active phase has the same dependence on stellar mass as does the gas cooling rate, suggesting the onset of the quiescent phase is due to fuel depletion. We find radio and emission line AGN activity to be independent, consistent with these corresponding to different accretion states.