Neutrino flows in collapsing stars - A two-fluid model

Abstract

The exchange of energy, momentum, and particle number between neutrino radiation and matter is calculated using a two-fluid model. The equations of radiative transfer are derived, and a closure relationship for the Eddington moments in the semitransparent region of a supernova is provided. Source terms are calculated, concentrating on the energy transfer. The flow of radiation is envisioned to be mainly free streaming, with local interactions with matter in the semitransparent regime providing only a perturbation. An approximate way to deal with blocking in the final leptonic states is introduced. Conclusions are drawn about the infall and late time hydrostatic stages of the supernova explosion.