Degeneracy of gravitational waveforms in the context of GW150914

We study the degeneracy of theoretical gravitational waveforms for binary black hole mergers using an aligned-spin effective-one-body model. After appropriate truncation, bandpassing, and matching, we identify regions in the mass spin parameter space containing waveforms similar to the template proposed for GW150914, with masses m(1) = 36(-4)(+5)M(circle dot) and m(2) = 29(-4)(+4)M(circle dot), using the cross-correlation coefficient as a measure of the similarity between waveforms. Remarkably high cross-correlations are found across broad regions of parameter space. The associated uncertanties exceed these from LIGO's Bayesian analysis considerably. We have shown that waveforms with greatly increased masses, such as m1 = 70M(circle dot) and m(2) = 35M(circle dot), and strong anti-aligned spins (x1 = 0.95 and x2 = 0.95) yield almost the same signal-to-noise ratio in the strain data for GW150914.