Fully general relativistic simulations of black holeneutron star mergers
Abstract
Black holeneutron star (BHNS) binaries are expected to be among the leading sources of gravitational waves observable by groundbased detectors, and may be the progenitors of shorthard gammaray bursts (SGRBs) as well. We discuss our new fully general relativistic calculations of merging BHNS binaries, which use highaccuracy, loweccentricity, conformal thinsandwich configurations as initial data. Our evolutions are performed using the moving puncture method and include a fully relativistic, highresolution shockcapturing hydrodynamics treatment. Focusing on systems in which the neutron star is irrotational and the black hole is nonspinning with a 3∶1 mass ratio, we investigate the inspiral, merger, and disk formation in the system. We find that the vast majority of material is promptly accreted and no more than 3% of the neutron star’s rest mass is ejected into a tenuous, gravitationally bound disk. We find similar results for mass ratios of 2∶1 and 1∶1, even when we reduce the neutron stars (NS) compaction in the 2∶1 mass ratio case. These ambient disks reach temperatures suitable for triggering SGRBs, but their masses may be too small to produce the required total energy output. We measure gravitational waveforms and compute the effective strain in frequency space, finding measurable differences between our waveforms and those produced by binary black hole mergers within the advanced LIGO band. These differences appear at frequencies corresponding to the emission that occurs when the NS is tidally disrupted and accreted by the black hole. The resulting information about the radius of the neutron star may be used to constrain the neutron star equation of state.
 Publication:

Physical Review D
 Pub Date:
 April 2008
 DOI:
 10.1103/PhysRevD.77.084002
 arXiv:
 arXiv:0712.2460
 Bibcode:
 2008PhRvD..77h4002E
 Keywords:

 04.25.D;
 04.25.dk;
 04.30.w;
 Numerical relativity;
 Numerical studies of other relativistic binaries;
 Gravitational waves: theory;
 Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 22 pages, 14 figures, fixed a few typos