Prasad Vaishak, Gupta Anshu, Bose Sukanta, Krishnan Badri, Schnetter Erik
Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007, India.
Department of Physics and Astronomy, Washington State University, 1245 Webster, Pullman, Washington 99164-2814, USA.
Phys Rev Lett. 2020 Sep 18;125(12):121101. doi: 10.1103/PhysRevLett.125.121101.
In a binary black hole merger, it is known that the inspiral portion of the waveform corresponds to two distinct horizons orbiting each other and that the merger and ringdown signals correspond to the final horizon being formed and settling down to equilibrium. However, we still lack a detailed understanding of the relation between the horizon geometry in these three regimes and the observed waveform. Here we show that the well-known inspiral chirp waveform has a clear counterpart on black hole horizons, namely, the shear of the outgoing null rays at the horizon. We demonstrate that the shear behaves very much like a compact binary coalescence waveform with increasing frequency and amplitude. Furthermore, the parameters of the system estimated from the horizon agree with those estimated from the waveform. This implies that even though black hole horizons are causally disconnected from us, assuming general relativity to be true, we can potentially infer some of their detailed properties from gravitational wave observations.
在双黑洞合并过程中，已知波形的旋进部分对应于两个相互绕转的不同视界，而合并和铃宕信号对应于最终视界的形成并趋于平衡。然而，我们仍然缺乏对这三种状态下视界几何形状与观测到的波形之间关系的详细理解。在此我们表明，著名的旋进啁啾波形在黑洞视界上有一个明确的对应物，即视界处出射类光测地线的剪切。我们证明，这种剪切的行为非常类似于频率和振幅不断增加的致密双星合并波形。此外，从视界估计的系统参数与从波形估计的参数一致。这意味着，即使黑洞视界与我们因果不相连，但假设广义相对论成立，我们有可能从引力波观测中推断出它们的一些详细性质。
