Search for an emission line of a gravitational wave background

TL;DR

This paper proposes an improved method for detecting a sharp emission line in the gravitational-wave background by optimizing frequency bin width, potentially enabling the discovery of early universe signals.

Contribution

It introduces an optimized data analysis technique for line GWB detection, highlighting the importance of frequency bin width for signal-to-noise ratio enhancement.

Findings

The commonly-used 0.25 Hz bin width is suboptimal, reducing detection sensitivity.

Smaller bin widths can significantly improve the signal-to-noise ratio.

Reanalyzing existing data with optimized bins may reveal early universe signals.

Abstract

In the light of the history of researches on electromagnetic wave spectrum, a sharp emission line of gravitational-wave background (GWB) would be an interesting observational target. Here we study an efficient method to detect a line GWB by correlating data of multiple ground-based detectors. We find that the width of frequency bin for coarse graining is a critical parameter, and the commonly-used value 0.25 Hz is far from optimal, decreasing the signal-to-noise ratio by up to a factor of seven. By reanalyzing the existing data with a smaller bin width, we might detect a precious line signal from the early universe.