Quasiequilibrium sequences of synchronized and irrotational binary neutron stars in general relativity: 1. Method and tests

By E. Gourgoulhon, K. Taniguchi, P. Grandclément, S. Bonazzola, J. Marck. 2000

162 citations recorded by the source corpus.

We present a numerical method to compute quasiequilibrium configurations of close binary neutron stars in the precoalescing stage. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational. The latter state is technically more complicated to treat than the former one (synchronized binary), but is expected to represent fairly well the late evolutionary stages of a binary neutron star system. As regards the gravitational field, an approximation of general relativity is used, which amounts to solving five of the ten Einstein equations (conformally flat spatial metric). The obtained system of partial differential equations is solved by means of a multidomain spectral method. Two spherical coordinate systems are introduced, one centered on each star; this results in a precise description of the stellar interiors. Thanks to the multidomain approach, this high precision is extended to the strong field regions. The computational domain covers the whole space so that exact boundary conditions are set to infinity. Extensive tests of the numerical code are performed, including comparisons with recent analytical solutions. Finally a constant baryon number sequence (evolutionary sequence) is presented in detail for a polytropic equation of state with $\ensuremath{\gamma}=2.$

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/a782fce174e18314e83c72ffbae794ead7a74406

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Citations in the corpus

Dynamical Mass Ejection from Binary Neutron Star Mergers (2016, methodology): “We construct the quasi-circular (low eccentricity) initial data using the LORENE pseudo-spectral elliptic solver (Gourgoulhon et al. 2001).”
Beyond second-order convergence in simulations of binary neutron stars in full general-relativity (2013, methodology): “The initial data is computed in the conformally flat approximation using theLORENE pseudo-spectral code (Gourgoulhon et al. 2001) and describes two equal-mass NSs in quasi-circular orbit.”
A 3+1 perspective on null hypersurfaces and isolated horizons (2005, background): “However, a unique solution of the extended conformal thin sandwich has been found for problems of direct astrophysical interest, like binary neutron stars [23,78,117,166] or binary black holes [79,54].”
Relativistic neutron star merger simulations with non-zero temperature equations of state. I. Variation of binary parameters and equation of state (2006, methodology): “It satifies the equations used by the helical killing vector (HKV) method (Shibata 1998; Gourgoulhon et al. 2001) to Newtonian order.”