Patryk Mach (Jagellonian University, Krakow, Poland)
"General-relativistic kinetic description of matter around black holes"

General-relativistic kinetic theory provides a description of matter around black holes alternative to the more popular hydrodynamical (or magnetohydrodynamical) approach. It is especially relevant when collisions between particles are rare and the mean free path is large. I will describe recent analytic models of accretion of a collisionless gas on black holes, including stationary accretion onto moving Schwarzschild black holes and thin-disk accretion in the Kerr spacetime. I will shortly discuss a Monte Carlo approach to the general-relativistic kinetic theory, useful in more complex cases, in which controlling the geometry of the phase-space available for the motion of individual gas particles is hard.