Viscosity caused by self-gravity in the field of a massive body.

This study investigates self-gravity-induced viscosity in collisionless systems in the presence of a massive central body. Employing a kinetic framework based on the Vlasov-Poisson equations, we derive an analytical expression for viscosity arising from self-gravitational interactions. It is found that a self-gravitating medium in an external gravitational field exhibits non-Newtonian fluid behavior with anisotropic properties.