Cooling of neutron stars with color superconducting quark cores
- Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany)
- Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany)
- Theory Division, GSI mbH, D-64291 Darmstadt (Germany)
We show that within a recently developed nonlocal, chiral quark model the critical density for a phase transition to color superconducting quark matter under neutron star conditions can be low enough for these phases to occur in compact star configurations with masses below 1.3 M{sub {center_dot}}. We study the cooling of these objects in isolation for different values of the gravitational mass. Our equation of state (EoS) allows for two-flavor color superconductivity (2SC) quark matter with a large quark gap ({approx}100 MeV) for u and d quarks of two colors that coexists with normal quark matter within a mixed phase in the hybrid star interior. We argue that, if the phases with unpaired quarks were allowed, the corresponding hybrid stars would cool too fast. If they occurred for M<1.3 M{sub {center_dot}}, as follows from our EoS, one could not appropriately describe the neutron star cooling data existing today. We discuss a ''2SC+X'' phase as a possibility for having all quarks paired in two-flavor quark matter under neutron star constraints, where the X gap is of the order of 10 keV-1 MeV. Density-independent gaps do not allow us to fit the cooling data. Only the presence of an X gap that decreases with increasing density would allow us to appropriately fit the data in a similar compact star mass interval to that following from a purely hadronic model. This scenario is suggested as an alternative explanation of the cooling data in the framework of a hybrid star model.
- OSTI ID:
- 20696104
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 71, Issue 4; Other Information: DOI: 10.1103/PhysRevC.71.045801; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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