The Equation of State and Some Key Parameters of Neutron Stars: Constraints from GW170817, the Nuclear Data, and the Low-mass X-Ray Binary Data

Abstract

In this work we parameterize the equation of state of dense neutron star (NS) matter with four pressure parameters of and then set the combined constraints with the data of GW170817 and the data of six low-mass X-ray binaries (LMXBs) with thermonuclear burst or alternatively the symmetry energy of the nuclear interaction. We find that the nuclear data effectively narrow down the possible range of , the gravitational-wave data plays the leading role in bounding , and the LMXB data as well as the lower bound on the maximal gravitational mass of non-rotating NSs govern the constraints on and . Using posterior samples of pressure parameters and some universal relations, we further investigate how the current data sets can advance our understanding of tidal deformability (Λ), moment of inertia ( I ), and binding energy (BE) of NSs. For a canonical mass of 1.4 M ⊙ , we have , , , and if the constraints from the nuclear data and the gravitational-wave data have been jointly applied. For the joint analysis of gravitational-wave data and the LMXB data, we have , , , and . These results suggest that the current constraints on Λ and R still suffer from significant systematic uncertainties, while I 1.4 and BE 1.4 are better constrained.