Non-radial fluid oscilation modes of color superconducting self-bound stars



We investigate the effect of color superconductivity on the non-radial oscillations of pure self-bound quark stars using an equation of state in the framework of the MIT bag model. The equations of non-radial oscillations are integrated within the Cowling approximation in order to determine the frequency of the fundamental mode and of the first and second pressure modes. We employ several parametrizations of the equation of state that result in a maximum mass larger than the mass of the recently observed PSR J1614–2230 and PSR J0348–0432 with M ≈ 2 M. The pulsation frequencies are compared with the corresponding modes of quark stars without pairing. For the fundamental mode, the oscillation frequency is typically 2–3 kHz. Parametrizations of the equations of state with larger values of the pairing gap Δ tend to give smaller values of the frequency. For the first and second pressure modes, the frequencies lie in the range 5–10 kHz for stars with masses above 1.5 M and diverge as the mass of the star tends to zero. From the numerical results we obtain parabolic fittings of the frequency of the fundamental mode as a function of the gravitational redshift at the surface of the star. For the p1 and p2 modes we find power law fittings that are rather independent of the parametrization of the equations of state. The here obtained results can be used to extract details about the internal composition of compact stars from observed modes of pulsation. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)