Luca Comisso (Columbia University)
Different mechanisms of black hole energy extraction have been carefully analyzed over the years, most notably the Penrose and Blandford-Znajek processes, providing us major insights on the mechanisms that might play a role in a number of highly energetic astrophysical phenomena, from active galactic nuclei to gamma-ray bursts to ultraluminous X-ray binaries. On the other hand, the possibility of extracting black hole rotational energy as a result of rapid reconnection of magnetic field lines has been generally overlooked. In this talk, we will analyze the mechanism of black hole energy extraction via fast magnetic reconnection as a function of the key parameters that regulate the process: black hole spin, reconnection location, orientation of the reconnecting magnetic field, and plasma magnetization. We will obtain the conditions under which black hole energy extraction occurs and we will quantify the rate of energy extraction and the reconnection efficiency in order to evaluate whether magnetic reconnection is an effective energy extraction mechanism for astrophysical purposes. In particular, we will see that magnetic reconnection in the ergosphere of a rapidly spinning black hole expels energized plasma that can exceed the energy originally stored in the magnetic field and might be responsible for black hole flares.
Zoom Meeting ID: 854 3210 3337