On the maximum mass of differentially rotating neutron stars

Abstract

A binary neutron star merger leads to the formation of a massive differentially rotating neutron star (or strange star) or to the prompt collapse to a black hole. The gravitational wave signal should tell us whether a massive neutron star or a black hole is formed and should allow to put constraints on the (hot) neutron star equation of state. We study the effect of the degree of differential rotation and of the stiffness of the equation of state on the maximum mass of neutron stars. We numerically construct stellar models using a highly accurate relativistic code based on a multi-domain spectral method (Ansorg, Gondek-Rosinska, Villain, 2009). We find various types of configurations, which were not considered in previous works, mainly due to numerical limitations. Among other results, we obtain the largest increase of the maximum mass for moderately stiff equation of state and for these new types of solutions.