Systematic Study of Gravitational Waves from Galaxy Merger
  A systematic study of gravitational waves from galaxy mergers, through N-body
simulations, was performed. In particular, we investigated the relative
importance of galaxy components (disk, bulge and halo) and effects of initial
relative velocity, relative angular momentum and mass ratio of the galaxies. We
found that the features of light curve of gravitational waves, such as peak
width and luminosity, are reliably simulated with particle numbers larger than
~10^4. Dominant contribution to gravitational wave emission came from the halo
component, while peak luminosity amounted to 10^31 erg/sec for the collision of
two halos with mass 3.8 x10^12Msun/h. We also found that the initial relative
velocity in the direction of the initial separation did not significantly
affect gravitational wave emission, while the initial relative angular momentum
broadened the peak width and suppressed the luminosity. Mass dependence of the
peak luminosity was also investigated, and we obtained evidence that the
luminosity is proportional to the cubic mass when the scaling relation is
satisfied. This behavior was considered by a simple analysis.
