Accurate Effective-One-Body waveforms of inspiralling and coalescing black-hole binaries

The Effective-One-Body (EOB) formalism contains several flexibility parameters, notably $a_5$, $\vp$ and $\a$. We show here how to jointly constrain the values of these parameters by simultaneously best-fitting the EOB waveform to two, independent, numerical relativity (NR) simulations of inspiralling and/or coalescing binary black hole systems: published Caltech-Cornell {\it inspiral} data (considered for gravitational wave frequencies $M\omega\leq 0.1$) on one side, and newly computed {\it coalescence} data on the other side. The resulting, approximately unique, "best-fit" EOB waveform is then shown to exhibit excellent agreement with NR coalescence data for several mass ratios. The dephasing between this best-fit EOB waveform and published Caltech-Cornell inspiral data is found to vary between -0.0014 and +0.0008 radians over a time span of $\sim 2464M$ up to gravitational wave frequency $M\omega= 0.1$, and between +0.0013 and -0.0185 over a time span of 96M after $M\omega=0.1$ up to $M\omega=0.1565$. The dephasings between EOB and the new coalescence data are found to be smaller than: (i) $\pm 0.025$ radians over a time span of 730M (11 cycles) up to merger, in the equal mass case, and (ii) $\pm 0.05$ radians over a time span of about 950M (17 cycles) up to merger in the 2:1 mass-ratio case. These new results corroborate the aptitude of the EOB formalism to provide accurate representations of general relativistic waveforms, which are needed by currently operating gravitational wave detectors.