We construct quasiequilibrium sequences of black hole-neutron star binaries in general relativity .
We solve Einstein ’ s constraint equations in the conformal thin-sandwich formalism , subject to black hole boundary conditions imposed on the surface of an excised sphere , together with the relativistic equations of hydrostatic equilibrium .
In contrast to our previous calculations we adopt a flat spatial background geometry and do not assume extreme mass ratios .
We adopt a \Gamma = 2 polytropic equation of state and focus on irrotational neutron star configurations as well as approximately nonspinning black holes .
We present numerical results for ratios of the black hole ’ s irreducible mass to the neutron star ’ s ADM mass in isolation of M _ { irr } ^ { BH } / M _ { ADM, 0 } ^ { NS } = 1 , 2 , 3 , 5 , and 10 .
We consider neutron stars of baryon rest mass M _ { B } ^ { NS } / M _ { B } ^ { max } = 83 % and 56 % , where M _ { B } ^ { max } is the maximum allowed rest mass of a spherical star in isolation for our equation of state .
For these sequences , we locate the onset of tidal disruption and , in cases with sufficiently large mass ratios and neutron star compactions , the innermost stable circular orbit .
We compare with previous results for black hole-neutron star binaries and find excellent agreement with third-order post-Newtonian results , especially for large binary separations .
We also use our results to estimate the energy spectrum of the outgoing gravitational radiation emitted during the inspiral phase for these binaries .