Rapidly Spinning Compact Stars with Deconfinement Phase Transition

We study rapidly spinning compact stars with equations of state featuring a first-order phase transition between strongly coupled nuclear matter and deconfined quark matter by employing the gauge/gravity duality. We consider a family of models that allow purely hadronic uniformly rotating stars with masses up to approximately 2.9M(circle dot), and are therefore compatible with the interpretation that the secondary component (2.59(-0.09)(+0.08)M(circle dot)) in GW190814 is a neutron star. These stars have central densities that are several times the nuclear saturation density, so that strong coupling and non-perturbative effects become crucial. We construct models where the maximal mass of static (rotating) stars M-TOV (M-max) is either determined by the secular instability or a phase-transition induced collapse. We find the largest values for M-max/M-TOV in cases where the phase transition determines M-max, which shifts our fit result to M-max/M-TOV = 1.227(-0.016)(+0.031), a value slightly above the Breu-Rezzolla bound 1.203(-0.022)(+0.022) inferred from models without phase transition.

Automated summary

The study focuses on rapidly spinning compact stars with a first-order phase transition between strongly coupled nuclear matter and deconfined quark matter. Models allow for purely hadronic uniformly rotating stars with masses up to approximately 2.9 solar masses, and the maximal mass is determined by the phase transition in cases with the largest values.