Gravitational wave tests of quantum modifications to black hole structure—with post-GW150914 update

A preliminary discussion is given of the prospects that gravitational-wave observations of binary inspiral of black holes (BHs) could reveal or constrain quantum modifications to BH dynamics, such as are required to preserve postulates of quantum mechanics. Different proposals for such modifications are characterized by different scales, and the size of these scales relative to those probed by observation of inspiral signals is important in determining the feasibility of finding experimental signatures. Certain scenarios with strong quantum modifications in a region extending well outside the horizon are expected to modify classical evolution, and distort the near-peak gravitational wave signal, suggesting a search for departures from waveforms predicted by general relativity. The near agreement of the GW150914 signal with such waveforms is discussed, and indicates constraints on some such scenarios. Important strategies for more precise future tests are (1) to develop more precise predictions from scenarios proposing quantum modifications, and (2) searching for observed deviations from numerical relativity predictions via analysis of gravity wave data, particularly focussing on the signal region corresponding to plunge and merger.