Higher mass limits of neutron stars from the equation of states in curved spacetime

Abstract

In order to solve the Tolman-Oppenheimer-Volkoff equations for neutron stars, one routinely uses the equation of states which are computed in the Minkowski spacetime. Using a first-principle approach, it is shown that the equation of states which are computed within the curved spacetime of the neutron stars include the effect of gravitational time dilation. It arises due to the radially varying interior metric over the length scale of the star and consequently it leads to a much higher mass limit. As an example, for a given set of parameters in a $\sigma-\omega$ model of nuclear matter, the maximum mass limit is shown to increase from $1.61 M_{\odot}$ to $2.24 M_{\odot}$ due to the inclusion of gravitational time dilation.