Conservative Formulations of General Relativistic Radiative Transfer
  Accurate accounting of particle number and 4-momentum in radiative transfer may be facilitated by the use of transport equations that allow transparent conversion between volume and surface integrals in both spacetime and momentum space. Such conservative formulations of general relativistic radiative transfer in multiple spatial dimensions are presented, and their relevance to core-collapse supernova simulations described. 
Christian Y. Cardall (Oak Ridge National Laboratory and University of   Tennessee, Knoxville)