  Black hole-neutron star (BHNS) binaries are expected to be among the leading
sources of gravitational waves observable by ground-based detectors, and may be
the progenitors of short-hard gamma ray bursts (SGRBs) as well. Here, we
discuss our new fully general relativistic calculations of merging BHNS
binaries, which use high-accuracy, low-eccentricity, conformal thin-sandwich
configurations as initial data. Our evolutions are performed using the moving
puncture method and include a fully relativistic, high-resolution
shock-capturing 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 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.
