Intrinsic selection biases of ground-based gravitational wave searches for high-mass black hole-black hole mergers

The next generation of ground-based gravitational wave detectors may detect a few mergers of comparable-mass $M\ensuremath{\simeq}100\ensuremath{-}1000{M}_{\ensuremath{\bigodot}}$ [``intermediate-mass'' (IMBH)] spinning black holes. Black hole spin is known to have a significant impact on the orbit, merger signal, and post-merger ringdown of any binary with non-negligible spin. In particular, the detection volume for spinning binaries depends significantly on the component black hole spins. We provide a fit to the single-detector and isotropic-network detection volume versus (total) mass and arbitrary spin for equal-mass binaries. Our analysis assumes matched filtering to all significant available waveform power (up to $l=6$ available for fitting, but only $l\ensuremath{\le}4$ significant) estimated by an array of 64 numerical simulations with component spins as large as ${S}_{1,2}/{M}^{2}\ensuremath{\le}0.8$. We provide a spin-dependent estimate of our uncertainty, up to ${S}_{1,2}/{M}^{2}\ensuremath{\le}1$. For the initial (advanced) LIGO detector, our fits are reliable for $M\ensuremath{\in}[100,500]{M}_{\ensuremath{\bigodot}}$ ($M\ensuremath{\in}[100,1600]{M}_{\ensuremath{\bigodot}}$). In the online version of this article, we also provide fits assuming incomplete information, such as the neglect of higher-order harmonics. We briefly discuss how a strong selection bias towards aligned spins influences the interpretation of future gravitational wave detections of IMBH-IMBH mergers.