Black hole behavior can be predicted (we have a theory, and we are then capable to make predictions). In this case, the predictions match the observations (and there is not any better explanation). This is why this is thought as a black hole merging phenomenon.
PS: note that this is not related to CERN at all ^^ And thanks for the nice comment!
No problem man. Glad to see you posting again!
I was away because of my job who started to be very demanding :) But I think I am now back ^^
excellent!