Abstract
We analyze gravitational-wave data from the first LIGO detection of a binary black-hole merger (GW150914) in search of the ringdown of the remnant black hole. Using observations beginning at the peak of the signal, we find evidence of the fundamental quasinormal mode and at least one overtone, both associated with the dominant angular mode (), with confidence. A ringdown model including overtones allows us to measure the final mass and spin magnitude of the remnant exclusively from postinspiral data, obtaining an estimate in agreement with the values inferred from the full signal. The mass and spin values we measure from the ringdown agree with those obtained using solely the fundamental mode at a later time, but have smaller uncertainties. Agreement between the postinspiral measurements of mass and spin and those using the full waveform supports the hypothesis that the GW150914 merger produced a Kerr black hole, as predicted by general relativity, and provides a test of the no-hair theorem at the level. An independent measurement of the frequency of the first overtone yields agreement with the no-hair hypothesis at the level. As the detector sensitivity improves and the detected population of black-hole mergers grows, we can expect that using overtones will provide even stronger tests.
- Received 5 May 2019
DOI:https://doi.org/10.1103/PhysRevLett.123.111102
© 2019 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Hunting for Hair on Coalescing Black Holes
Published 12 September 2019
A fresh look at data from the first detected black-hole merger supports the “no hair” theorem and proves the potential of black-hole spectroscopy.
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