Equations of State and Maximum Mass of Neutron Stars in Light of PSR   J1614-2230
  We shall examine various types of equations of state for neutron stars, which determine the structure of neutron stars. In particular, the relation between mass and radius of neutron stars is of primary consideration. By combining an equation of state (EOS) with the Tolmann-Oppenheimer-Volkoff structure equations, we can determine the theoretical maximum mass of a neutron star for a given equation of state. One question we seek to answer is whether quark matter can exist in the core of a neutron star. In light of the discovery of pulsar PSR J1614-2230, the mass of which is observed to be 1.97 solar masses, a valid equation of state must achieve a maximum mass that is greater than 2 solar masses. To try to solve this problem, we experiment with different sets of parameters for the quark matter to try to meet the lower limit 2-solar-mass criterion. It is found that certain parameters contribute significantly to the maximum mass of a neutron star. 
Carlos Daniel Xu
astro-ph.SR nucl-th