Gravitational waveform model based on photon motion for spinning black holes

TL;DR

This paper introduces a novel method for modeling gravitational waveforms from spinning black holes using photon sphere properties, providing accurate ringdown signals that match numerical relativity results and can extend to other compact objects.

Contribution

The paper presents a new approach to compute quasinormal modes of spinning black holes via photon sphere analysis, improving waveform modeling for complex black hole scenarios.

Findings

Waveforms match numerical relativity results very well.

Method extends to parametrized axisymmetric black holes.

Recoil acceleration effects are undetectable in ringdown signals.

Abstract

The waveforms from binary black hole mergers include inspiral, merger, and ringdown parts. Usually, the inspiral waveform can be obtained by calibrating from post-Newtonian approximation; The merger and ringdown ones can be gotten from the quasinormal modes with black hole perturbation theory. However, for more general black holes, the calculation of the quasinormal modes is not trivial. In this paper we use the photon sphere to get the quasinormal modes of spinning black holes. Then we connect the ringdown wave with the inspiral part to get full waveforms and compare with the ones from numerical relativity. We find that they match with each other very well. In principle this method can be extended to some general compact objects. As an example, the ringdown waveforms from parametrized axisymmetric black holes are obtained. We also use this method to get the ringdown signals of the accelerating final black hole; this is due to gravitational recoil during the merger. Even for the extreme cases, the acceleration due to the recoil cannot produce detectable effects.