Influence of hyperon coupling constant on the properties of hybrid stars

In terms of the relativistic mean field theory, which describes the hadronic matter, and the NJL model, which characterizes the quark matter, the influence of hyperon coupling constant on the properties of hybrid stars is studied. The numerical results show that with the increase of the hyperon coupling constant the phase transition density decreases, the equation of state in the mixed phase range stiffens, and the maximum mass and the corresponding radius increase. When the hyperon coupling constant increases from 0.73 to 1, the maximum mass of the star increases from 1.68 solar mass to 1.82 solar mass and the corresponding radius of the star changes from 11.4 km to 12.5 km. The result also shows that the different hadronic equations of state have different influence on the properties hybrid stars. This model is suitable for describing the hybrid stars with big masses and small quark cores. (authors)