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arXiv · 2306.11142

Nonlinear ringdown at the black hole horizon

Neev Khera·Ariadna Ribes Metidieri·Béatrice Bonga·Xisco Jiménez Forteza·Badri Krishnan·Eric Poisson·Daniel Pook-Kolb·Erik Schnetter·Huan Yang
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Abstract

The gravitational waves emitted by a perturbed black hole ringing down are well described by damped sinusoids, whose frequencies are those of quasinormal modes. Typically, first-order black hole perturbation theory is used to calculate these frequencies. Recently, it was shown that second-order effects are necessary in binary black hole merger simulations to model the gravitational-wave signal observed by a distant observer. Here, we show that the horizon of a newly formed black hole after the head-on collision of two black holes also shows evidence of non-linear modes. Specifically, we identify one quadratic mode for the $l=2$ shear data, and two quadratic ones for the $l=4,6$ data in simulations with varying mass ratio and boost parameter. The quadratic mode amplitudes display a quadratic relationship with the amplitudes of the linear modes that generate them.

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Neev Khera, Ariadna Ribes Metidieri, Béatrice Bonga, Xisco Jiménez Forteza, Badri Krishnan, Eric Poisson, Daniel Pook-Kolb, Erik Schnetter, Huan Yang. 2023-06-19. Nonlinear ringdown at the black hole horizon. https://doi.org/10.1103/physrevlett.131.231401

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