Zoom info: zoom https://stanford.zoom.us/j/93437242416

LISA is likely to provide a wealth of information about galactic nuclei. One widely anticipated gravitational-wave source would be the merger of a stellar mass black hole and a supermassive black hole which is enabled by the latter's accretion disc. We highlight 4 pieces of physics which are both relevant for this scenario and are far from being completely understood: 1. Magnetic levitation of accretion discs 2. Resonant friction on discs in rotating galactic nuclei 3. Negative dynamical friction on black holes in dense gaseous medium, and 4. Impact of captured cosmic string loops on spins of supermassive black holes.