Constraints on a phenomenologically parametrized neutron-star equation of state

We introduce a parametrized high-density equation of state (EOS) in order to systematize the study of constraints placed by astrophysical observations on the nature of neutron-star matter. To obtain useful constraints, the number of parameters must be smaller than the number of EOS-related neutron-star properties measured, but large enough to accurately approximate the large set of candidate EOSs. We find that a parametrized EOS based on piecewise polytropes with 3 free parameters matches, to about 4% rms error, an extensive set of candidate EOSs at densities below the central density of $1.4{M}_{\ensuremath{\bigodot}}$ stars. Adding observations of more massive stars constrains the higher-density part of the…

• NS
  National Science Foundation
• PS
  Pennsylvania State University