Finding quark content of neutron stars in light of GW170817

The detection of gravitational waves from GW170817 has provided a new opportunity to constrain the equation of state (EOS) of neutron stars. In this article, we investigate the possible existence of quarks inside the neutron star core in the context of GW170817. The nucleon phase is treated within the relativistic nuclear mean-field approach where we have employed a fully comprehensive set of available models, and the quark phase is described in the Bag model. We show that the nucleonic EOSs which are inconsistent with the tidal deformability bound become consistent when phase transition to quark matter via Gibbs construction is allowed. We find that several nucleonic EOSs support the presence of pure quark matter core with a small mass not more than 0.17M(circle dot) confined within a radius of 0.9 km. We also find that the strong correlation between tidal deformability and neutron star radii observed for pure nucleonic stars does persist even with a nucleon-quark phase transition and provides an upper limit on the radius of R-1.4 less than or similar to 12.9 km for a 1.4M(circle dot) neutron star.

Automated summary

The detection of gravitational waves from GW170817 has provided an opportunity to study the possible existence of quarks inside neutron star cores. It was found that several nucleonic EOSs can support the presence of a pure quark matter core within a small mass and radius. Even with a nucleon-quark phase transition, the strong correlation between tidal deformability and neutron star radii persists and provides an upper limit on the radius for a 1.4M neutron star.