Abstract

We use fully nonlinear numerical relativity techniques to estimate the maximum gravitational radiation emitted by high energy head-on collisions of nonspinning, equal-mass black holes. Our simulations include improvements in the construction of initial data, subsequent full numerical evolutions, and the computation of waveforms at infinity. The new initial data significantly reduce the spurious radiation content, allowing for initial speeds much closer to the speed of light, i.e., v∼0.99c. Using these new techniques, we estimate the maximum radiated energy from head-on collisions to be Emax/MADM=0.13±0.01. This value differs from the second-order perturbative (0.164) and zero-frequency-limit (0.17) analytic computations but is close to those obtained by thermodynamic arguments (0.134) and by previous numerical estimates (0.14±0.03)