An effective equation of state which generalizes the Lattimer-Swesty equation for nuclear matter is presented for matter at supernuclear densities including strange baryons .
It contains an adjustable baryon potential energy density , based on models of local potentials for the baryon-baryon interactions .
The features of the equation rely on the properties of nuclei for the nucleon-nucleon interactions , and mainly on experimental data from hypernuclei for the hyperon-nucleon and hyperon-hyperon interactions .
The equation is used to calculate equilibrium compositions and thermodynamic properties of high density matter with strangeness in two astrophysical contexts : neutron star matter ( transparent to neutrinos ) and proto-neutron star matter ( opaque to neutrinos ) .
The effective equation of state reproduces typical properties of high density matter found in theoretical microscopic models .
Of these , the main result is that hyperons appear in both types of matter at about twice the nuclear saturation density , and that their appearance significantly softens the equation of state .
The range of maximal masses of neutron stars found in a comprehensive parameter survey is 1.4-1.7 M _ { \odot } .
Another typical result is that the maximal mass of a proto-neutron star with strange baryons is higher than that of an evolved neutron star ( opposite to the case of nuclear matter ) , setting the stage for a “ delayed collapse ” scenario .