Numerical solution of the general relativistic Boltzmann equation for massive and massless particles

The ADM formalism of general relativity is applied to write the Einstein and matter equations for a spherically symmetric spacetime whose gravitational sources are taken to be represented by ordinary matter, described by a perfect fluid approximation, and either massless or massive weakly interacting particles, for which a kinetic-theory description is employed. The Boltzmann equation, which is solved directly, is written in a form which is particularly amenable to numerical treatment, and for which massive particles can be accommodated as easily as massless ones. Some of the numerical methods used to solve these equations are described and the results of several code tests are discussed. The behavior of massive and massless particles is compared, and results are presented from a code for the cooling of a crude model of a 'neutron star' by emission of massive particles. 33 refs