Computation of gravitational waves from inspiraling binary neutron stars in quasiequilibrium circular orbits: Formulation and calibration - art. no. 104017

Gravitational waves from binary neutron stars in quasiequilibrium circular orbits are computed using an approximate method which we propose in this pa per. In the first step of-this method, we prepare general relativistic irro tational binary neutron stars in a quasiequilibrium circular orbit, neglect ing gravitational waves. We adopt the so-called conformal flatness approxim ation for a three-metric to obtain the quasiequilibrium states in this pape r. In the second step, we compute gravitational waves, solving linear pertu rbation equations in the background spacetime of the quasiequilibrium state s. Comparing numerical results with post-Newtonian waveforms and luminosity of gravitational waves from two point masses in circular orbits, we demons trate that this method can produce accurate waveforms and luminosity of gra vitational waves. It is shown that the effects of tidal deformation of neut ron stars and strong general relativistic gravity modify the post-Newtonian results for compact binary neutron stars in close orbits. We indicate that the magnitude of a systematic error in quasiequilibrium states associated with the conformal flatness approximation is fairly large for close and com pact binary neutron stars. Several formulations for improving the accuracy of quasiequilibrium states are proposed.