Mechanism of the Changing Look phenomenon in Active Galactic Nuclei

Understand

Changing-look phenomenon observed now in a growing number of active galaxies challenges our understanding of the accretion process close to a black hole.

• We propose a simple explanation for periodic outbursts in sources operating at a few per cent of the Eddington limit.
• The mechanism is based on two relatively well understood phenomena: radiation pressure instability and formation of the inner optically thin Advection-Dominated Accretion Flow.
• The limit cycle behaviour takes place in a relatively narrow transition zone between the standard disk and optically thin flow.