Equations of State and Maximum Mass of Neutron Stars in Light of PSR J1614-2230

TL;DR

This paper investigates various equations of state for neutron stars, focusing on their maximum mass predictions, especially in light of the 1.97 solar mass pulsar PSR J1614-2230, to assess the possibility of quark matter in their cores.

Contribution

It explores how different parameters in quark matter equations of state affect the maximum mass of neutron stars, aiming to meet the observed mass constraint.

Findings

Certain parameters significantly increase the maximum neutron star mass.

Some equations of state can produce masses exceeding 2 solar masses.

The existence of quark matter in neutron star cores remains plausible with suitable parameters.

Abstract

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.