Strong Warps in Black Hole Accretion Disks

Classical accretion disks are geometrically thin, radiatively efficient and mechanized by turbulent viscosity. Yet, many observational and theoretical issues challenge this standard model, suggesting that we are missing essential-but-overlooked physics, such as warped accretion. When black holes rotate, they twist up the surrounding space-time, torquing any matter that lives nearby. If an accretion disk is tilted with respect to the black hole spin, it becomes twisted up, developing a warp. Warps dramatically alter the accretion process and the resulting observables. I will discuss the internal hydrodynamic mechanisms that allow strong warps to drive the rapid inflow of gas to the black hole — far quicker than in classical thin disks. Strong enough warps also tear the disk apart into multiple, individually precessing “sub-disks”. These sub-disks lead short, violent lives as they crash into each other. I will present synthetic observations of disk tearing events and draw connections to poorly-understood "changing-look'' events in active galactic nuclei. In particular, I will propose a method to measure accretion disk tearing in active galactic nuclei, allowing us to detect strong warps in real systems.


Note:

 The talk starts at 4pm and over the zoom only. 
https://zoom.us/j/9290951953