Kinetic Plasmas around Black Holes

Benjamin Crinquant – IRAP

A variety of astrophysical phenomena can only be explained as being powered by black holes. Black-hole activity can manifest itself through the launching of a relativistic jet, or the production of short, intense gamma-ray flares. Recent progress in instrumentation has allowed us to probe these processes with unprecedented detail. For example, the GRAVITY collaboration reported the detection of flaring hot spots orbiting near the supermassive black hole Sgr A, whereas the Event Horizon Telescope collaboration released in 2019 the first image of the “shadow” of M87. For the first time, the immediate vicinity of the black hole can be spatially resolved.

To account for these various observations, which all point to fast energy dissipation in the surrounding plasma, it is necessary to understand the plasma physics at play in the innermost environment of black holes. For example, magnetic reconnection is believed to provide a crucial link between theory and observations, by quickly and efficiently converting the magnetic energy stored in these systems into radiation. In this talk, I will present recent efforts to model black-hole magnetospheres and coronae from first principles. To do so, I will show the results of global general-relativistic kinetic simulations which can capture both the non-ideal kinetic physics of the radiating plasma, and the knowledge of where and under which physical conditions dissipation occurs. I will also address how to connect the microphysics of these plasmas with observables.