Assuming two black holes with the same rest mass $m$ collid coming from infinity with velocity $v$ and impact parameter $b$. Lets ignore spin at first. For which values of $v$ and $b$ would these holes scatter or merge?
Using $G=c=m=1$ one unit of length would be half of the Schwarzschild radius from one of the black holes. Therefore for $b<4$ the holes would clearly merge because the event horizons will overlap. But what would happen for greater values of $b$ is there some simple merging condition?