Temperature profiles of accretion discs around rapidly rotating strange stars in general relativity: A comparison with neutron stars

We compute the temperature profiles of accretion discs around rapidly rotat ing strange stars, using constant gravitational mass equilibrium sequences of these objects, considering the full effect of general relativity. Beyond a certain critical value of stellar angular momentum (J), we observe the r adius (r(orb)) of the innermost stable circular orbit (ISCO) to increase wi th J (a property seen neither in rotating black holes nor in rotating neutr on stars). The reason for this is traced to the crucial dependence of d tau (orb)/dJ on the rate of change of the radial gradient of the Keplerian ang ular velocity at rorb with respect to J. The structure parameters and tempe rature profiles obtained are compared with those of neutron stars, as an at tempt to provide signatures for distinguishing between the two. We show tha t when the full gamut of strange star equation of state models, with varyin g degrees of stiffness are considered, there exists a substantial overlap i n properties of both neutron stars and strange stars. However, applying acc retion disc model constraints to rule out stiff strange star equation of st ate models, we notice that neutron stars and strange stars exclusively occu py certain parameter spaces. This result implies the possibility of disting uishing these objects from each other by sensitive observations through fut ure X-ray detectors.