Quasiequilibrium black holeneutron star binaries in general relativity
Abstract
We construct quasiequilibrium sequences of black holeneutron star binaries in general relativity. We solve Einstein’s constraint equations in the conformal thinsandwich 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 Γ=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 holeneutron star binaries and find excellent agreement with thirdorder postNewtonian 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.
 Publication:

Physical Review D
 Pub Date:
 April 2007
 DOI:
 10.1103/PhysRevD.75.084005
 arXiv:
 arXiv:grqc/0701110
 Bibcode:
 2007PhRvD..75h4005T
 Keywords:

 04.30.Db;
 04.25.Dm;
 04.40.Dg;
 Wave generation and sources;
 Numerical relativity;
 Relativistic stars: structure stability and oscillations;
 General Relativity and Quantum Cosmology;
 Astrophysics
 EPrint:
 17 pages, 15 figures, published in Phys. Rev. D