AGN flickering and chaotic accretion

Observational arguments suggest that the growth phases of the supermassive black holes in active galactic nuclei have a characteristic time-scale ∼10[Superscript: 5] yr. We show that this is the time-scale expected in the chaotic accretion picture of black hole feeding, because of the effect of self-gravity in limiting the mass of any accretion-disc feeding event.