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Ringdown gravitational waves from close scattering of two black holes (2310.18686v1)
Published 28 Oct 2023 in gr-qc, astro-ph.HE, and hep-th
Abstract: We have numerically investigated close scattering processes of two black holes (BHs). Our careful analysis shows for the first time a non-merging ringdown gravitational wave coming from dynamical tidal deformations of individual BHs during their close encounter. The ringdown wave frequencies turn out to agree well with the quasi-normal ones of a single BH in perturbation theory, despite its distinctive physical context from the merging case. Our study shows a new type of gravitational waveform and opens up a new exploration of strong gravitational interactions using BH encounters.