Numerical approach for high precision 3D relativistic star models

A multidomain spectral method for computing very high precision three-dimensional stellar models is presented. The boundary of each domain is chosen in order to coincide with a physical discontinuity (e.g., the star’s surface). In addition, a regularization procedure is introduced to deal with the infinite derivatives on the boundary that may appear in the density field when stiff equations of state are used. Consequently all the physical fields are smooth functions on each domain and the spectral method is absolutely free of any Gibbs phenomenon, which yields to a very high precision. The power of this method is demonstrated by direct comparison with analytical solutions such as MacLaurin spheroids and Roche ellipsoids. The relative numerical error is revealed to be of the order of ${10}^{-10}.$ This approach has been developed for the study of relativistic inspiralling binaries. It may be applied to a wider class of astrophysical problems such as the study of relativistic rotating stars too.