2/3/2021

Tidal disruption events (TDEs) happen when a star comes too close to a massive black and gets ripped apart by the tidal forces. This can result in a flash of radiation that can shine across the entire electo-magnetic spectrum and can last from months to years. Thanks to modern optical sky surveys like the Zwicky Transient Facility (ZTF), ASASSN, ATLAS and Gaia, TDEs of events are now being discovered at an increasing pace. Over the time period during which the star is fed to the black hole, the accretion rate in TDEs can vary significantly from sub-Eddington to super-Eddington and vice versa. This provides us with an unique opportunity to study the entire accretion cycle onto individual supermassive black holes. In contrast, most Active Galactic Nuclei (AGN) are thought to evolve on viscous times which are thousands to ten of thousands of years. I will present multi-year monitoring observations of AT2018fyk in the X-ray, optical, UV and the radio wavebands. Using this data I will argue that the system transitions through the various accretion states (soft to hard to quiescent states) in a manner remarkably similar to stellar-mass black holes when they go into outbursts. Our findings illustrate that TDEs can be used to study the scale (in)variance of accretion processes in individual supermassive black holes. Consequently, they provide a new avenue to study accretion states over seven orders of magnitude in black hole mass, removing limitations inherent to commonly used ensemble studies.