Possible confirmation of the existence of ergoregion by the Kerr quasinormal mode in gravitational waves from Pop III massive black hole binary

Abstract

The existence of the ergoregion of the Kerr space-time has not been confirmed observationally yet. We show that the confirmation would be possible by observing the quasinormal mode in gravitational waves. As an example, using the recent population synthesis results of Pop III binary black holes, we find that the peak of the final merger mass ($M_f$) is about $50{\mathrm{M}}_{\odot }$, while the fraction of the final spin $q_f=a_f/M_f>0.7$ needed for the confirmation of a part of ergoregion is $\sim 77\%$. To confirm the frequency of the quasinormal mode, $\mathrm{SNR}>35$ is needed. The standard model of Pop III population synthesis tells us that the event rate for the confirmation of more than $50\%$ of the ergoregion by the second generation gravitational wave detectors is $\sim 2.3$ $\mathrm{events}\mathrm{y}{\mathrm{r}}^{-1}(\mathrm{SF}{\mathrm{R}}_{\mathrm{p}}/(10^{-2.5}{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-3}))\cdot ([{\mathrm{f}}_{\mathrm{b}}/(1+{\mathrm{f}}_{\mathrm{b}})]/0.33)$ where $\mathrm{SF}{\mathrm{R}}_{\mathrm{p}}$ and ${\mathrm{f}}_{\mathrm{b}}$ are the peak value of the Pop III star formation rate and the fraction of binaries, respectively.

Accepted for publication in PTEP. Comments welcome

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Cited by in corpus (6)

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• Chirp Mass and Spin of Binary Black Holes from First Star Remnants
• GW150914-like Black Holes as Galactic High-Energy Sources
• Estimate of the radius responsible for quasinormal modes in the extreme Kerr limit and asymptotic behavior of the Sasaki-Nakamura transformation
• Gravitational wave quasinormal mode from Population III massive black hole binaries in various models of population synthesis