Neutron star cooling constraints for color superconductivity in hybrid stars

We apply the recently developed logN-logS test of compact star cooling theories for the first time to hybrid stars with a color superconducting quark matter core. Although there is not yet a microscopically founded superconducting quark matter phase that would fulfill constraints from cooling phenomenology, we explore the hypothetical 2SC+X phase and show that the magnitude and density dependence of the X-gap can be chosen to satisfy a set of tests: temperature-age (T-t), the brightness constraint, logN-logS, and the mass spectrum constraint. The latter test appears as a new conjecture from the present investigation.