Unequal Mass Binary Black Hole Plunges and Gravitational Recoil

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We present results from fully nonlinear simulations of unequal mass binary black holes plunging from close separations well inside the innermost stable circular orbit with mass ratios q = M₁/M₂ = 1,0.85,0.78,0.55,0.32, or equivalently, with reduced mass parameters η=M₁M₂/(M₁+M₂)² = 0.25, 0.248, 0.246, 0.229, 0.183. For each case, the initial binary orbital parameters are chosen from the Cook-Baumgarte equal-mass ISCO configuration. We show waveforms of the dominant l=2,3 modes and compute estimates of energy and angular momentum radiated. For the plunges from the close separations considered, we measure kick velocities from gravitational radiation recoil in the range 25-82 km/s. Due to the initial close separations our kick velocity estimates should be understood as a lower bound. The close configurations considered are also likely to contain significant eccentricities influencing the recoil velocity.