Critical rotation of general-relativistic polytropic models simulating neutron stars: A post-Newtonian hybrid approximative scheme

We develop a hybrid approximative scheme in the framework of the post-Newtonian approximation for computing general-relativistic polytropic models simulating neutron stars in critical rigid rotation. We treat the differential equations governing such a model as a complex initial value problem, and we solve it by using the so-called complex-plane strategy. We incorporate into the computations the complete solution for the relativistic effects, this issue representing a significant improvement with regard to the classical post-Newtonian approximation, as verified by extended comparisons of the numerical results. (C) 2015 Elsevier B.V. All rights reserved.