It is possible to infer the mass and spin of the remnant black hole from binary black hole mergers by comparing the ringdown gravitational wave signal to results from studies of perturbed Kerr spacetimes. Typically, these studies are based on the fundamental quasinormal mode of the dominant $\ell =m=2$ harmonic. By modeling the ringdown of accurate numerical relativity simulations, we find, in agreement with previous findings, that the fundamental mode alone is insufficient to recover the true underlying mass and spin, unless the analysis is started very late in the ringdown. Including higher overtones associated with this $\ell =m=2$ harmonic resolves this issue and provides an unbiased estimate of the true remnant parameters. Further, including overtones allows for the modeling of the ringdown signal for all times beyond the peak strain amplitude, indicating that the linear quasinormal regime starts much sooner than previously expected. This result implies that the spacetime is well described as a linearly perturbed black hole with a fixed mass and spin as early as the peak. A model for the ringdown beginning at the peak strain amplitude can exploit the higher signal-to-noise ratio in detectors, reducing uncertainties in the extracted remnant quantities. These results should be taken into consideration when testing the no-hair theorem.

中文翻译：

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黑洞铃声：泛音的重要性

通过将ringdown引力波信号与对扰动的Kerr时空的研究结果进行比较，可以从二元黑洞合并中推断出残留黑洞的质量和自旋。通常，这些研究基于显性的基本准正态模式$\ell =米=\mathrm{2个}$谐波。通过对精确的数值相对论模拟的振铃进行建模，与先前的发现一致，我们发现，仅基本模式不足以恢复真实的基础质量和自旋，除非该分析在振铃中开始得很晚。包括与此相关的较高泛音$\ell =米=\mathrm{2个}$谐波解决了这个问题，并提供了真实余量参数的无偏估计。此外，包括泛音允许对超出峰值应变幅度的所有时间的振铃信号进行建模，这表明线性准正态状态比以前预期的要早得多。该结果表明，时空被很好地描述为线性扰动的黑洞，其质量固定，并且最早在峰值时旋转。从峰值应变幅度开始的振铃模型可以利用检测器中较高的信噪比，从而减少提取的残余量的不确定性。测试无毛定理时，应考虑这些结果。