Modeling the Black Hole Merger of QSO 3C 186

Recent detailed observations of the radio-loud quasar 3C 186 indicate the possibility that a supermassive recoiling black hole is moving away from the host galaxy at a speed of nearly 2100 km s(-1). If this is the case, we can model the mass ratio and spins of the progenitor binary black hole using the results of numerical relativity simulations. We find that the black holes in the progenitor must have comparable masses with a mass ratioq= m(1)/m(2)> 1 / 4 and the spin of the primary black hole must be alpha(2) = S-2 / m(2)(2) > 0.5. The final remnant of the merger is bounded by alpha(f) > 0.5, and at least 4% of the total mass of the binary system is radiated into gravitational waves. We consider four different pre-merger scenarios that further narrow those values. Assuming, for instance, a cold accretion driven merger model, we find that the binary had comparable masses with q = 0.58(-0.19)(+0.39) and the normalized spins of the larger and smaller black holes were alpha(1) = 0.93(-0.31)(+0.05) and alpha(2) = 0.93(-0.10)(+0.06). We can also estimate the final recoiling black hole spin alpha(f) = 0.91(-0.05)(+0.02) and that the system radiated 8.6(-1.8)(+1.0)% of its total mass, making the merger of those black holes the most energetic event ever observed.