Introduction

Gravitational wave astronomy will open a new observational window on the universe. Since large masses concentrated in small volumes and moving at high velocities generate the strongest, and therefore most readily detectable waves, the final coalescence of blackhole binaries is expected to be one of the strongest sources. During the last century, the opening of the full electromagnetic spectrum to astronomical observation greatly expanded our understanding of the cosmos. In this new century, observations across the gravitational wave spectrum will provide a wealth of new knowledge, including accurate measurements of binary black-hole masses and spins.

The high frequency part of the gravitational wave spectrum, ~10 Hz ≲ f ≲ 103 Hz, is being opened today through the pioneering efforts of first-generation ground-based interferometers such as the Laser Interferometer Gravitational-Wave Observatory (LIGO), currently operating at design sensitivity.