Gravitational waves from axions annihilation through quantum field theory

TL;DR

This paper calculates gravitational waves produced by axion annihilation around Kerr black holes using a scattering method, providing analytical results and cross-checks for numerical approaches.

Contribution

It introduces a novel analytical approach to compute gravitational wave emission from axion annihilation, incorporating Kerr black hole spin effects.

Findings

Analytical approximation for gravitational wave power from axion annihilation

Inclusion of Kerr black hole spin effects in the calculation

Provides a cross-check for traditional numerical methods

Abstract

We use the scattering method to calculate the gravitational wave from axions annihilation in the axion cloud formed by the superradiance process around the Kerr black hole. We consider axions annihilating to gravitons as a three-body decay process and then calculate the corresponding decay width. In this approach, we can simply obtain the radiation power of gravitational wave and give the analytical approximate result with the spin effects of the Kerr black hole. Our study can also provide a cross-check to the numerical results in the traditional method.