An Effective Search Method for Gravitational Ringing of Black Holes

TL;DR

This paper presents an optimized search method for detecting gravitational ringdown signals from black holes using matched filtering, effectively handling both white and colored noise with efficient template tiling.

Contribution

The paper introduces a novel tiling method for matched filtering that remains effective in colored noise, improving detection efficiency for black hole ringdown signals.

Findings

The tiling method is analytically validated for white noise.

The method remains effective with colored noise based on numerical analysis.

Detection efficiency is maximized under computational constraints.

Abstract

We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasi-normal modes that are excited when a black hole geometry is perturbed. The detection of it will be a direct confirmation of the existence of a black hole. Assuming that the ringdown waves are dominated by the fundamental mode with least imaginary part, we consider matched filtering and develop an optimal method to search for the ringdown waves that have damped sinusoidal wave forms. When we use the matched filtering method, the data analysis with a lot of templates required. Here we have to ensure a proper match between the filter as a template and the real wave. It is necessary to keep the detection efficiency as high as possible under limited computational costs. First, we consider the white noise case for which the matched filtering can be studied analytically. We construct an efficient method for tiling the template space. Then, using a fitting curve of the TAMA300 DT6 noise spectrum, we numerically consider the case of colored noise. We find our tiling method developed for the white noise case is still valid even if the noise is colored.