Neutrino emission processes in white dwarfs and neutron stars

Abstract

The neutrino emission processes play essential roles in the evolution of white dwarfs and neutron stars. The neutrino energy loss rates in dense stars have been recently calculated using the Weinberg-Salam theory. The most dominant neutrino energy loss processes involving electrons are the pair, photo-, plasma, and bremsstrahlung neutrino processes. According to the calculation by Munakata, Kohyama, and Itoh, the neurtino energy loss rates due to pair, photo-, and plasma processes in the framework of the Weinberg-Salam theory are found to be substantially lower than the result obtained by Beaudet, Petrosian, and Salpeter for the Feynman-Gell-Mann theory. The reduction factor α is in the range 0.35⪅ α ⪅ 0.88 depending on the neutrino masses, density, and temperature. The ionic correlation effects play important roles in the bremsstrahlung neutrino process. Itoh, Kohyama, and their collaborators recently calculated the bremsstrahlung neutrino energy loss rate taking into account the ionic correlation effects in the crystalline lattice state as well as in the liquid metal state. They have found that the ionic correlation effects reduce the bremsstrahlung neutrino energy loss typically by a factor 2–20.