Empirical tests of the black hole no-hair conjecture using gravitational-wave observations

TL;DR

This paper demonstrates that second-generation gravitational-wave detectors can test the black hole no-hair conjecture by analyzing the ringdown phase of binary black hole mergers, achieving about 1.5% accuracy with multiple observations.

Contribution

It introduces a method to measure black hole parameters and test the no-hair conjecture using gravitational-wave data and numerical relativity models.

Findings

Ability to measure black hole parameters from ringdown

Verification of the no-hair conjecture with ~1.5% accuracy

Combining data from ~5 mergers improves confidence

Abstract

We show that second-generation gravitational-wave detectors at their design sensitivity will allow us to directly probe the ringdown phase of binary black hole coalescences. This opens the possibility to test the so-called black hole no-hair conjecture in a statistically rigorous way. Using state-of-the-art numerical relativity-tuned waveform models and dedicated methods to effectively isolate the quasi-stationary perturbative regime where a ringdown description is valid, we demonstrate the capability of measuring the physical parameters of the remnant black hole, and subsequently determining parameterized deviations from the ringdown of Kerr black holes. By combining information from $\mathcal{O}(5)$ binary black hole mergers with realistic signal-to-noise ratios achievable with the current generation of detectors, the validity of the no-hair conjecture can be verified with an accuracy of $\sim 1.5\%$ at $90\%$ confidence.