Composition and stability of hybrid stars with hyperons and quark color-superconductivity

Institute for Theoretical Physics, J.-W. Goethe University, 60438 Frankfurt-Main, Germany
e-mail: sedrakian@th.physik.uni-frankfurt.de

Received: 5 August 2011
Accepted: 26 October 2011

Abstract

The recent measurement of a 1.97 ± 0.04 solar-mass pulsar places a stringent lower bound on the maximum mass of compact stars and therefore challenges the existence of any agents that soften the equation of state of ultra-dense matter. We investigate whether hyperons and/or quark matter can be accommodated in massive compact stars by constructing an equation of state based on a combination of phenomenological relativistic hyper-nuclear density functional and an effective model of quantum chromodynamics (the Nambu-Jona-Lasinio model). Stable configurations are obtained with M ≥ 1.97   M_⊙ featuring hyper-nuclear and quark matter in color superconducting state if the equation of state of nuclear matter is stiff above the saturation density, the transition to quark matter takes place at a few times the nuclear saturation density, and the repulsive vector interactions in quark matter are substantial.