Constraints on the equation of state of neutron star matter based on observations

Abstract

Many calculations of the neutron star (NS) equation of state (EOS) have been performed over the years. Recent observations of NSs have begun to play an important role in finding the realistic EOS. In this paper, we compare mass–radius relations derived from various EOSs with observational data of NSs. In addition, we adjust EOSs to be consistent with observational data from NSs and employ Bayesian statistical analyses to obtain constraints on the EOS. Our results show that the EOS needs to be softened in the medium density region ([Formula: see text]–[Formula: see text], where [Formula: see text] is the saturation density) and to have a rapid change of stiffness around an energy density of [Formula: see text] 650 MeV/fm3.