Construction of highly accurate models of rotating neutron stars – comparison of three different numerical schemes

¹ Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153, Japan
² Department of Physics, University of Wisconsin-Milwaukee, PO box 413, Milwaukee, WI 53201, U.S.A.
³ Département d'Astrophysique Relativiste et de Cosmologie, UPR 176 du CNRS, Observatoire de Paris, F-92195 Meudon Cedex, France

Send offprint request to: E. Gourgoulhon

Received: 15 April 1998
Accepted: 6 May 1998

Abstract

We conduct a direct comparison of three different representative numerical codes for constructing models of rapidly rotating neutron stars in general relativity. Our aim is to evaluate the accuracy of the codes and to investigate how the accuracy is affected by the choice of interpolation, domain of integration and equation of state. In all three codes, the same physical parameters, equations of state and interpolation method are used. We construct 25 selected models for polytropic equations of state and 22 models with realistic neutron star matter equations of state. The three codes agree well with each other (typical agreement is better than 0.1% to 0.01%) for most models, except for the extreme assumption of uniform density stars. We conclude that the codes can be used for the construction of highly accurate initial data configurations for polytropes of index (which typically correspond to realistic neutron stars), when the domain of integration includes all space and for realistic equations with no phase transitions. With the exception of the uniform density case, the obtained values of physical parameters for the models considered in this paper can be regarded as "standard” and we display them in detail for all models.