Covariant Radiative Transfer for Black Hole Spacetimes

It has now become possible to study directly, via numerical simulation, the evolution of relativistic, radiation-dominated flows around compact objects. With this in mind we set out explicitly covariant forms of the radiative transfer equation that are suitable for numerical integration in curved spacetime or flat spacetime in curvilinear coordinates. Our work builds on and summarizes in consistent form earlier work by Lindquist, Thorne, Morita & Kaneko, and others. We give explicitly the basic equations in spherical polar coordinates for Minkowski space and the Kerr spacetime in Kerr-Schild coordinates.