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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. Large changes in the cold disk are due to the irradiation by the hot flow with accretion rate strongly varying during the cycle. The model gives quantitative predictions and works well for multiple outbursts of NGC 1566.
We study the properties of the host galaxies of Changing-Look Active Galactic Nuclei (CL AGNs) with the aim of understanding the conditions responsible for triggering CL activity. We find that CL AGN hosts primarily reside in the so-called green vall
Changing-look active galactic nuclei (CL-AGNs) as a new subpopulation challenge some fundamental physics of AGNs because the timescales of the phenomenon can hardly be reconciled with accretion disk models. In this Letter{textit{}}, we demonstrate th
The nature of the rare Changing-look (CL) phenomenon in active galactic nuclei (AGNs) is still under debate at current stage. We here present it Swift/rm XRT and UVOT follow-up observations of UGC,3223, a newly discovered repeat CL-AGN with type tran
The changes of broad emission lines should be a crucial issue to understanding the physical properties of changing-look active galactic nucleus (CL-AGN). Here, we present the results of an intensive and homogeneous 6-month long reverberation mapping
We here report a spectroscopic identification of two new changing-look AGNs (CL-AGNs): SDSS,J104705.16+544405.8 and SDSS,J120447.91+170256.8 both with a turn-off type transition from type 1 to type 1.8/1.9. The identification is arrived by a follow-u