We are developing 3 dimensional simulation codes for coalescing binary neutron stars. A code using the maximal slicing condition is obtained. To evaluate the gravitational radiation, we implemented a gaugeinvariant wave extraction and compared the wave forms with the metric tensors at the wave zone. The energy spectrum of the waves was also evaluated to investigate the possibility that the excitation of the quasinormal modes of the black hole, which may be formed after the merger of two stars, can be observed. 
Fig.1Density \rho_n on the xy plane. (movies) 
Fig.2 Plots rh+ and rhx along zaxis as a function of tr. 
Fig.3Plots r^3 h+ and r^3 hx as a function of t. 
Fig.4 Plots Wave forms rh+ and rhx along zaxis as a function of tr. 
Fig.5The comparison h shown in Fig.4 (blue lines) and h defined by Eqs.(6.9) and (6.10) (red lines). 
Fig.6 The propagation of the gravitational waves. (movies) 
Fig.7The luminosity dE/dt and total energy E emitted as gravitational waves up to t. 
Fig.8Lapse function \alpha (solid lines) and density \rho. 
Fig.9The energy spectrum of the gravitational waves. 
denxy.mpg (2.8MB) Density \rho_n on the xy plane. 

denxyxz.mpg (4.7MB) Density \rho_n on the xy and xz plane. 

gwexy.mpg (2.8MB) The propagation of the gravitational waves on the xy plane. 

gwexyxz.mpg (5.0MB) The propagation of the gravitational waves on the xy and xz plane. 