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General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
We revisit the recent debate on the evidence for an overtone in the black
hole ringdown of GW150914. By gating and inpainting the data, we discard the
contamination from earlier parts of the gravitational wave signal before
ringdown. This enables the parameter estimation to be conducted in the
frequency domain, which is mathematically equivalent to the time domain method.
We keep the settings as similar as possible to the previous studies by
\textcite{Cotesta:2022pci} and Isi \textit{et
al.}\cite{Isi:2019aib,Isi:2022mhy} which yielded conflicting results on the
Bayes factor of the overtone. We examine the spectral contents of the
matched-filtering in the frequency domain, and propose a convergence test to
assess the validity of an overtone model. Our results find the Bayes factors
for the overtone fall within $10$ and $26$ around a range of times centered at
the best-fit merger time of GW150914, which supports the existence of an
overtone in agreement with the conclusions of Isi \textit{et
al.}\cite{Isi:2019aib,Isi:2022mhy}. Our work contributes to the understanding
of how various methods affect the statistical significance of overtones.
