Testing the no-hair theorem with GW150914. (arXiv:1905.00869v1 [gr-qc])
<a href="http://arxiv.org/find/gr-qc/1/au:+Isi_M/0/1/0/all/0/1">Maximiliano Isi</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Giesler_M/0/1/0/all/0/1">Matthew Giesler</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Farr_W/0/1/0/all/0/1">Will M. Farr</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Scheel_M/0/1/0/all/0/1">Mark A. Scheel</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Teukolsky_S/0/1/0/all/0/1">Saul A. Teukolsky</a>
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 ($ell=m=2$). 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
${sim}10%$ 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.
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 ($ell=m=2$). 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
${sim}10%$ 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.
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