What is the Source of 3 Sun M Energy Released in BH Merger?

[clinden]

Each of the two BHs in the collision brought in matter and energy prior to merge, neither emitting any significant energy prior to merge. Same for the combined BH after merger was complete. So, my question is, what is the source or mechanism for the 3 Sun M worth of energy release into gravitational energy as part of the merger process?

 

[mathman]

The black holes weren't emitting energy, but they had plenty (internally) available for the collision physics.

 

[clinden]

I am sorry, but I don't understand your answer. Are you implying the gravitational wave energy came from the kinetic energy of the 2 pre-collision BHs?

 

[PeterDonis]

Each of the two BHs in the collision brought in matter and energy prior to merge

Actually, black holes are vacuum (at least, as far as classical solutions are concerned); they aren't made of matter and energy in the usual sense. They are made of spacetime curvature. GWs are also made of spacetime curvature, so the emission of GWs as the two holes merged was just spacetime curvature being propagated.