Rapidly rotating neutron stars with realistic nuclear matter equation of state

We performed a comparison of three different numerical codes for constructing equilibrium models; (I) a code for static equilibrium configurations, (II) an implementation of the Hartle–Thorne slow-rotation approximation, (III) a numerical solution of the full Einstein equations by $\mathtt{\text{LORENE}}$. We aimed to construct sequences of uniformly rotating configurations at various rotation frequencies up to the Keplerian frequency for a hybrid hadronic–quark matter EOS where a smooth transition is provided between two separate phases. We investigated the difference of between the results computed by the implementation of Hartle–Thorne slow-rotation approximation and by $\mathtt{\text{LORENE/nrotstar}}$, respectively. We have conclude that the codes can the difference between the slow rotating and the fast-rotating approach increase exponentially, reaching 6.67% for the maximal mass configuration rotating at the Keplerian frequency.