Eur. Phys. J. C (2013) 73: 2545
https://doi.org/10.1140/epjc/s10052-013-2545-0

Regular Article - Theoretical Physics

Radial oscillations of quark stars with strongly coupled QGP in the interior

Department of Physics, University of Calicut, Kerala, 673635, India

^* e-mail: sineeba@gmail.com

Received: 17 June 2013
Published online: 28 August 2013

Abstract

The radial oscillations of quark stars are analysed using the recently developed strongly coupled quark–gluon plasma (SCQGP) equation of state. This EOS describes the intermediate to strongly coupled phase of deconfined cold quark matter wherein the chiral symmetry has not yet been restored. By integrating the Chandrasekhar eigenequation governing the radial modes we obtain the periods for the fundamental and first overtone, which are plotted for different values of the confining parameter—the bag constant (B)—pertaining to the equation of state. The eigenfunctions of some of the normal modes are also plotted and analysed. It is found that for lower mass quark stars the oscillation periods are typically of the order of one tenth of a millisecond and has negligible dependence on the bag parameter. For medium and higher mass stars a variation of pulsation period with change in the bag constant is seen—the period increases with increase in B. Comparing with strange stars composed of non-interacting quarks we see that the corresponding pulsation periods show considerable difference throughout the entire range of stellar masses with the difference increasing with decrease in B value (increasing stiffness) for the SCQGP equation of state. Finally we study the damping of small amplitude radial pulsations via non-equilibrium processes. We derive the corresponding neutrino emissivities in the SCQGP case and present the resulting temporal evolution of pulsation energies.