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arXiv · 1404.3197

Modeling Ringdown: Beyond the Fundamental Quasi-Normal Modes

Lionel London·James Healy·Deirdre Shoemaker
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Abstract

While black hole perturbation theory predicts a rich quasi-normal mode structure, technical challenges have limited the numerical study of excitations to the fundamental, lowest order modes caused by the coalescence of black holes. Here, we present a robust method to identify quasi-normal mode excitations beyond the fundamentals within currently available numerical relativity waveforms. In applying this method to waveforms of initially non-spinning black hole binaries, of mass ratios 1 to 15, we find not only the fundamental quasi-normal mode amplitudes, but also overtones, and evidence for 2nd order quasi-normal modes. We find that the mass-ratio dependence of quasi-normal mode excitation is very well modeled by a Post-Newtonian like sum in symmetric mass ratio. Concurrently, we find that the mass ratio dependence of some quasi-normal modes is qualitatively different from their Post-Newtonian inspired counterparts, suggesting that the imprints of nonlinear merger are more evident in some modes than in others. We present new fitting formulas for the related quasi-normal mode excitations, as well as for remnant black hole spin and mass. We also discuss the relevance of our results in terms of gravitational wave detection and characterization.

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Lionel London, James Healy, Deirdre Shoemaker. 2017-02-21. Modeling Ringdown: Beyond the Fundamental Quasi-Normal Modes. https://doi.org/10.1103/physrevd.90.124032

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