Beta decay of pion condensates as a cooling mechanism for neutron stars

Abstract

Recently developed dynamical models of pion condensation are used to reconsider the analysis of Bahcall and Wolf (1965), who showed that the existence of free pions in neutron-star interiors could stimulate neutron beta-decay and thus increase dramatically the rate at which these stars cool. Although the actual pion condensate is quite different from the free pions assumed by Bahcall and Wolf and although the stimulated beta-decay process is also different, the final results for the luminosity arising from this mechanism are very similar to their earlier predictions. The manner in which the pion condensate enters into the complete scenario of neutron-star cooling is indicated, and several questions are discussed which must be resolved before the full cooling process can be known quantitatively.