Legacy of Boson Clouds on Black Hole Binaries.

Superradiant clouds of ultralight bosons can leave an imprint on the gravitational waveform of black hole binaries through "ionization" and "resonances." We study the sequence of resonances as the binary evolves and show that there are only two possible outcomes, each with a distinct imprint on the waveform. If the cloud and the binary are nearly counterrotating, then the cloud survives in its original state until it enters the sensitivity band of future gravitational wave detectors, such as the Laser Interferometer Space Antenna.