Origin and Interpretation of Kilohertz Quasi-periodic Oscillations from Strange Stars in an X-Ray Binary System: Theoretical Hydrodynamical Description

We model and interpret kilohertz quasi-periodic oscillations (QPOs) from the hydrodynamical description of an accretion disk around a rapidly rotating compact strange star. The higher QPO frequency is described by the viscous effects of an accretion disk leading to shocks, while the lower one is taken to be the Keplerian motion of the accreting matter. Comparing our results with the observations for two of the fastest rotating compact stellar candidates, namely, 4U 1636-53 and KS 1731-260, we find that they match to a very good approximation and thus interpret them as strange stars.