Collisionless Accretion onto a Spinning Black Hole

Note unusual time and zoom 

Event Horizon Telescope observations of M87* and Sgr A*, together with multiwavelength campaigns, are providing an unprecedented view of the plasma surrounding supermassive black holes. In these systems, the accreting plasma is hot, dilute, and effectively collisionless: electrons and ions need not share the same temperature, and particle heating and nonthermal acceleration depend on kinetic processes that standard fluid models do not capture self-consistently. Understanding these processes is essential for connecting the dynamics of accretion and jet launching to the observed emission.

In this talk, I will present our group’s progress in modeling these systems from first principles using the GPU-based general relativistic particle-in-cell code Aperture. Starting from analytic equilibria for collisionless tori, I will describe the first global, axisymmetric kinetic simulations of accretion with finite angular momentum onto a spinning black hole. These simulations recover key features of magnetically arrested accretion and reveal how kinetic instabilities regulate pressure anisotropy, helping explain the emergence of fluid-like behavior. I will also discuss the implications for the plasma supply to the jet funnel and the conditions needed to sustain relativistic jets.