The work "Spectroscopy of Kerr black holes with Earth- and space-based interferometers," by Berti, Sesana, Barausse, Cardoso and Belczynski was recently accepted in Physical Review Letters.
Advanced LIGO detected gravitational waves from merging black holes with surprisingly high signal-to-noise ratio. The oscillation frequencies of the merger remnant can be used - just like atomic lines - to do black hole spectroscopy: they will tell us whether the merger remnant is indeed a rotating black hole, as predicted by Einstein's general relativity. However, black hole spectroscopy requires signal-to-noise ratios higher than the first LIGO detection.
In this paper, we use state-of-the-art astrophysical models of black hole formation and a comprehensive catalog of projected noise sensitivities to answer the following question: how many events will allow us to do black hole spectroscopy in the future, as we improve our detectors? Is it sufficient to upgrade Earth-based interferometers or do we need a space-based detector such as eLISA, whose technological feasibility was recently demonstrated by the spectacular success of LISA Pathfinder?
We find that significant improvements in Earth-based detectors (or better data analysis techniques) will be necessary to routinely perform black hole spectroscopy on Earth, while most massive black hole merger detections in space will allow us to test the black hole nature of the remnant.