Parameterized neutron star and proto-neutron star equation of state at finite temperature

Read et al. proposed a parameterized equation of state (EOS) giving the pressure P as a function of the rest mass density rho in a piecewise polytropic form for the study of neutron stars. The parameterized piecewise polytropic EOS can accurately represent many realistic EOS tables at zero temperature. We showed that the treatment can be extended to finite temperature to cover the study of neutron star at non zero temperature and proto-neutron stars. At finite temperature, two types of thermodynamic relations are needed, one for the pressure P and one for the internal energy density u. We show that for many finite temperature realistic EOS tables, both the P and u can be accurately represented in piecewise polytropic forms as functions of the rest mass density rho and temperature T. The polytropic parameterization provides a framework to compare and understand the properties of the different realistic EOSs.