Rotating compact strange stars

Abstract

We compute numerical models of uniformly rotating strange stars (SS) in general relativity for the recently proposed QCD-based equation of state (EOS) of strange quark matter (Dey et al. 1998). Static models based on this EOS are characterised by a larger surface redshift than strange stars within the MIT bag model. The frequencies of the fastest rotating configurations described by Dey model are much higher than these for neutron stars (NS) and for the simplest SS MIT bag model. We determine a number of physical parameters for such stars and compare them with those obtained for NS. We construct constant baryon mass equilibrium sequences both normal and supramassive. Similarly to the NS a supramassive SS, prior to collapse to a black hole, spins up as it loses angular momentum. We find the upper limits on maximal masses and maximal frequencies of the rotating configurations. We show that the maximal rotating frequency for each of considered evolutionary sequences is never the Keplerian one. A normal and low mass supramassive strange stars gaining angular momentum always slows down just before reaching the Keplerian limit. For a high mass supramassive SS sequence the Keplerian configuration is the one with the lowest rotational frequency in the sequence. The value of $T/W$ for rapidly rotating SS of any mass is significantly higher than those for ordinary NS. For Keplerian configurations it increases as mass decreases. The results are robust for all linear self-bound equations of state.