Fast rotation of strange stars

TL;DR

This paper presents a new numerical method to model rapidly rotating strange stars composed of self-bound quark matter, revealing their unique stability properties and maximum rotation parameters within general relativity.

Contribution

It introduces a novel numerical technique for modeling rotating strange stars with density discontinuities and derives exact formulas for their maximum rotation and mass.

Findings

Maximum rotation frequency depends on the bag constant.

Rapidly rotating strange stars have higher T/W ratios than neutron stars.

Strange stars may be more susceptible to triaxial instabilities.

Abstract

Exact models of uniformly rotating strange stars, built of self bound quark matter, are calculated within the framework of general relativity. This is made possible thanks to a new numerical technique capable to handle the strong density discontinuity at the surface of these stars. Numerical calculations are done for a simple MIT bag model equation of state of strange quark matter. Evolutionary sequences of models of rotating strange stars at constant baryon mass are calculated. Maximally rotating configurations of strange stars are determined, assuming that the rotation frequency is limited by the mass shedding and the secular instability with respect to axisymmetric perturbations. Exact formulae which give the dependence of the maximum rotation frequency, and of the maximum mass and corresponding radius of rotating configurations, on the value of the bag constant, are obtained. The values of T/W for rapidly rotating massive strange stars are significantly higher than those for ordinary neutron stars. This might indicate particular susceptibility of rapidly rotating strange stars to triaxial instabilities.