Fig. 1-1 Initial Configuration of Binary |

Evolution is performed on an AMR (Adaptive Mesh Refinement) grid. The
outermost grid is 394 M x 394 M, the innermost refinement
level for the BH is 2.8 M x 2.8 M and the innermost
refinement level for the NS is 3.3 M x 3.3 M. Here M is
the total (ADM) mass of the intial system. The innermost resolution is
ΔX_{min}/M = 1/32.5 while the outermost is
ΔX_{max}/M = 3.94. In this simulation, the
initial binary coordinate separation is D_{0}/M =
8.81, the initial angular momentum of the system is J/M^{2} = 0.702, the mass ratio is M_{BH}:M_{NS} = 3:1, and the black hole
spin parameter is J_{BH}/M_{BH}^{2} = 0.00. (Note:
The open circle in the lower right-hand corner of the above figure is a
clock.)

The neutron star obeys a polytropic equation of state, P = Kρ_{0}^{ Γ}, at
t = 0. It is evolved according to the
adiabatic evolution law, P =
(Γ-1)ρ_{0}&epsilon, where P is the pressure, K
the polytropic constant, &epsilon is the internal specific energy,
Γ is the adiabatic index, and ρ_{0} the rest-mass
density. We chose Γ = 2 to mimick
stiff nuclear matter. The star is irrotational (nonspinning) and
in a quasiequilibrium circular orbit.

The initial compaction of the neutron star is M_{NS}/R_{NS} = 0.145.
The rest mass is 83% of the maximum rest mass of an isolated, nonrotating NS with the same
polytropic EOS.

The initial binary is in a quasiequilibrium circular orbit. The matter and gravitational field variables are determined by using the conformal thin-sandwich formalism. BH equilibrium boundary conditions are imposed on the BH horizon.

In the clip, the rest-mass density of the neutron star is plotted on a logarithmic scale normalized to the initial central density. The gravitational field is evolved via the BSSN scheme using "moving puncture" gauge conditions. The relativistic hydrodynamic equations are solved using a high-resolution shock-capturing (HRSC) method.

After two orbits the density contours are for the most part undisturbed. After 3.5 orbits the first few density contours have crossed into the apparent horizon. The NS tail deforms into a quasistationary disk, as the bulk of the matter is all accreted onto the hole in a few periods.

Fig. 2-1 Color code for density profile |
Fig. 2-2 Density Profile at t/M = 450 |

Fig. 2-3 Density Profile at t/M = 500 |
Fig. 2-4 Density Profile at t/M = 900 |

Fig. 3-1 h_{+} in both hemispheres |
Fig. 3-2 h_{+} in one hemisphere |

Fig. 3-1 h_{×} both hemispheres |

J_{BH}/M_{BH}^{2} |
0.559 |

ΔJ_{GW}/J |
17.4% |

ΔE_{GW}/M |
0.93% |

Recoil velocity | 33 km/s |