Merger of black hole-neutron star binaries in full general relativity

We present our latest results of simulation for merger of black hole (BH) neutron star (NS) binaries in full general relativity which is performed preparing a quasicircular state as the initial condition. The BH is modelled by a moving puncture with no spin and the NS by the Gamma-law equation of state with Gamma = 2 and a corotating velocity field as a first step. The mass of the BH is chosen to be approximate to 3.2M(circle dot) or 4.0M(circle dot), and the rest mass of the NS approximate to 1.4M(circle dot) with a relatively large radius of the NS approximate to 13 -14 km. The NS is tidally disrupted near the innermost stable orbit, but similar to 80 -90% of the material is swallowed into the BH and the resulting disc mass is not very large as similar to 0.3M(circle dot) even for a small BH mass similar to 3.2M (circle dot). The result indicates that the system composed of BH and a massive disc of approximate to M-circle dot is not formed from nonspinning BH -NS binaries irrespective of the BH mass, although a disc of mass similar to 0.1M (circle dot) is a possible outcome for this relatively small BH mass range as approximate to 3 -4M(circle dot). Our results indicate that the merger of low-mass BH and NS may form a central engine of short-gamma-ray bursts.