Equation of state from nuclear and astrophysical evidence.

Abstract

Data on the nuclear equation of state from a number of different sources, from nuclei, high energy nuclear collisions, supernova, and neutron stars are analyzed. The current situation concerning supernova simulations is critically appraised. It is found that simulations that have achieved a prompt ejection do so with an equation of state that is too soft to support the measured masses of several known neutron stars. It is concluded that supernova explosions have not been proven to provide a significant constraint on the nuclear equation of state. Additionally it is concluded that the theoretical bias used to interpret data on neutron star masses as if they belonged to a population all having the same mass (of 1.4M/sub sun/) is unjustified. Evidence from the various nuclear data and neutron star masses favor a high compression modulus, Kapprox. =300 MeV. No definitive statement can be made about the equation of state at higher density, save that the neutron star equation of state must be moderately stiff to accommodate neutron stars of mass approx. =1.85M/sub sun/.