Post-Newtonian SPH calculations of binary neutron star coalescence. III. Irrotational systems and gravitational wave spectra

摘要: Gravitational wave (GW) signals from coalescing binary neutron stars may soon become detectable by laser-interferometer detectors. Using our new post-Newtonian (PN) smoothed particle hydrodynamics (SPH) code, we have studied numerically the mergers of star binaries with irrotational initial configurations. These are most physically realistic conditions just prior to merger, since in these systems expected be spinning slowly at large separation, and viscosity matter is too small for tidal synchronization effective separation. However, shear that develops during merger makes particularly difficult study 3D. In addition, PN gravity, accurate much more construct than corotating conditions. Here describe a method constructing circular orbits gravity. We then compute 3D hydrodynamic evolution until two completely merged, determine corresponding GW signals. present results different mass ratios, represented polytropes $\ensuremath{\Gamma}=2$ or $\ensuremath{\Gamma}=3.$ Compared binaries, find produce similar peak luminosities, but they shed almost no all distances. The dependence signal on numerical resolution calculations performed $N\ensuremath{\gtrsim}{10}^{5}$ SPH particles extremely weak, excellent agreement between runs utilizing ${N=10}^{5}$ ${N=10}^{6}$ (the largest calculation ever such mergers). also energy spectra based reported here previous works. effects lead clearly identifiable features spectrum mergers, which yield important information about nuclear equation state extreme densities.