SHAO Astrophysics Colloquium

Title:  The UV/optical Stochastic Variability as a Symptom of the AGN Central Engine Crisis
Speaker: Mouyuan Sun (XMU)

Time: 3:00 pm,  Sep 24th (Thursday)

Location: Lecture hall, 3rd floor

You can also connect with this zoom room: 

- id: 910 9697 5942

- passwd: 2010

Abstract: 

The AGN central engine is widely believed to be described by the classical thin accretion disk around a supermassive black hole. The classical thin disk model, which was developed roughly half century ago, can satisfactorily explain the overall UV-to-optical spectral energy distributions of AGNs. By far, one of the most serious challenges that we face is the long-standing AGN UV/optical stochastic variability. While the variability amplitude is only about 0.1 on timescales of years, UV/optical light curves can act as a tool to explore the size of the accretion disk which is impossible to spatially resolve. In this work, I’ll show that the observed AGN UV/optical stochastic variability is incompatible with the static thin accretion disk model in many aspects (i.e., the so called “AGN viscosity crisis” by Lawrence, 2018). Moreover, I’ll present our solution to this AGN central engine crisis. In the end, I’ll briefly discuss the possible future directions for AGN UV/optical stochastic variability studies in the era of time-domain astronomy.