The equation of state and composition of hot, dense matter in core-collapse supernovae

Abstract

The equation of state (EOS) and composition of matter are calculated for conditions typical for pre-collapse and early collapse stages in core-collapse supernovae. The composition is evaluated under the assumption of nuclear statistical equilibrium, when the matter is considered as an "almost" ideal gas with corrections owing to thermal excitations of nuclei, to free nucleon degeneracy, and to Coulomb and surface-energy corrections. The account of these corrections allows us to obtain the composition for densities that are slightly below the nuclear matter density. Through comparisons with the EOS developed by Shen et al., which is used in most of recent supernova simulations, we examine the differences of our EOS in the multi-composition with the EOS in the approximation of one representative nucleus. We find that widely distributed compositions in the nuclear chart are different because of the different mass formulae we used, while the thermodynamical quantities are quite close to those in Shen's EOS. © 2011 ESO.