Effect of the equation of state on the maximum mass of differentially rotating neutron stars

• Published in: Monthly notices of the Royal Astronomical Society Vol. 463; no. 3; p. 2667
• Main Authors: Studzinska, A M, Kucaba, M, Gondek-Rosinska, D, Villain, L, Ansorg, M
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 11.12.2016
• Subjects: Binary stars; Black holes; Differential rotation; Double stars; Equations of state; Gravitational waves; Mathematical models; Neutron stars; Stars; Stellar rotation; Supernovae
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw2152

Knowing the value of the maximum mass of a differentially rotating relativistic star is a key step towards the understanding of the signals to be expected from the merger of binary neutron stars, one of the most awaited alternative sources of gravitational waves after binary black holes. In this paper, we study the effects of differential rotation and of the equation of state on the maximum mass of rotating neutron stars modelled as relativistic polytropes with various adiabatic indices. Calculations are performed using a highly accurate numerical code, based on a multidomain spectral method. We thoroughly explore the parameter space and determine how the maximum mass depends on the stiffness, on the degree of differential rotation and on the maximal density, taking into account all the types of solutions that were proven to exist in a preceding paper. The highest increase with respect to the maximum mass for non-rotating stars with the same equation of state is reached for a moderate stiffness. With differential rotation, the maximum mass can even be 3-4 times higher than it is for static stars. This result may have important consequences for the gravitational wave signal from coalescing neutron star binaries or for some supernovae events.