Jet Dynamics in Black Hole Fields: A Collimation Mechanism

摘要

We study the axial collimation of the vortical geodesics in the field of a rotating black hole. This effect manifests itself when the energy and angular momenta of the particles that move on those geodesics vary slowly in dynamical time. In this paper we deduce the constraints that ensure collimation and show how the latter arises when the orbital parameters are perturbed by a given electromagnetic field or by pressure gradients.