Institute for Advanced Study Informal Astrophysics Seminar

The membrane paradigm gives an alternate description of black hole physics, in which the black hole is replaced by a fluid membrane living on the horizon. In asymptotically flat spacetimes, the boundary at null infinity also has a membrane description. I will explain how this reformulation is useful for understanding black hole astrophysics. The universal scaling of black hole jet power with black hole spin, observed in GRMHD simulations, can be explained by a simple impedance matching argument between the membranes at the horizon and at infinity. The membrane picture is also useful for understanding jet power from boosted black holes. Finally, I will discuss the close relationship between the membrane paradigm and the Bondi-Metzner-Sachs (BMS) invariance of gravitational scattering.