Accretion of gas on black holes powers many energetic phenomena in the universe. The accretion power generally comes out as radiation, but sometimes also as relativistic jets. The region close to the black hole, where accreting magnetized gas disappears through the horizon and where the jet originates, involves complex nonlinear physics. In the case of a few nearby supermassive black holes, thanks to the Event Horizon Telescope, this region will soon be amenable to direct observational study. Meanwhile, theoretical study of the nonlinear physics of black hole accretion has become practical with the development of numerical codes to simulate multi-dimensional radiation MHD flows in general relativistic space-times. However, poor understanding of the underlying plasma processes is a severe bottleneck and needs to be addressed before we can expect convergence between theoretical models and observations.
Host: Deepto Chakrabarty