Observational Evidence for Young Radio Galaxies are Triggered by Accretion Disk Instability

TL;DR

This study provides observational evidence that radiation pressure instabilities in accretion disks trigger the short-lived active phases of young radio galaxies, linking their ages with luminosity and outburst durations.

Contribution

It demonstrates the correlation between galaxy ages and luminosities, supporting the theory that accretion disk instabilities cause the episodic activity in young radio galaxies.

Findings

A positive correlation between galaxy age and bolometric luminosity.

Consistency of galaxy ages with theoretical outburst durations.

Evidence supporting radiation pressure instability as a trigger mechanism.

Abstract

The bolometric luminosities and black hole (BH) masses are estimated by various methods for a sample of young radio galaxies with known ages. We find that the ages are positively correlated with the bolometric luminosities in these young radio galaxies, which is consistent with theoretical prediction based on radiation pressure instability of accretion disk in Czerny et al. The ages of young radio galaxies are also found to be consistent with the theoretical durations of outbursts in BH mass and accretion rate (in Eddington unit) plane, where the outbursts are assumed to be triggered by the radiation pressure instabilities. Our results provide the observational evidence for the radiation pressure instability, which causes limit-cycle behavior, as a physical mechanism that may be responsible for these short-lived young radio galaxies.