In order to solve the Tolman-Oppenheimer-Volkoff equations for neutron stars, one routinely uses the equations of state which are computed in the Minkowski spacetime. Using a first-principle approach, it is shown that the equations of state 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 $1.61M_{\odot }$ to $2.24M_{\odot }$ due to the inclusion of gravitational time dilation.

• Received 27 September 2021
• Accepted 10 November 2021

DOI:https://doi.org/10.1103/PhysRevD.104.123005