Institute for Advanced Study Astrophysics Seminar

Stellar mass black holes with stellar companions on circular orbits can become powerful X-ray sources when mass is transferred from the star to the hole. In this talk, inspired by recent observations of RE J1034 +396, I will consider what happens when the black hole is massive and resides in a galactic nucleus. I will argue that stars on bound orbits will spiral inward under the action of gravitational radiation and often overflow their Roche lobes close to the hole. At this point the orbit is likely to expand while the star transfers mass to the hole via a relativistic torus and creates periodic X-ray emission from an orbiting hot spot. Prospects for observing this phenomenon and exhibiting general relativistic features will be discussed.