Gravitational Wave Confusion Noise

TL;DR

This paper uses information theory to refine the estimate of the confusion noise limit in gravitational wave astronomy, suggesting the background becomes unresolvable at a higher frequency than previously thought.

Contribution

It introduces an information theoretic approach to determine the confusion limit, improving upon ad-hoc rules used in prior estimates.

Findings

Confusion noise limit corresponds to more than one source per eight frequency bins.

The estimated frequency for galactic binaries becoming noise increases from 1.45 mHz to 2.54 mHz.

Provides a more realistic estimate of the gravitational wave background resolvability.

Abstract

One of the greatest challenges facing gravitational wave astronomy in the low frequency band is the confusion noise generated by the vast numbers of unresolved galactic and extra galactic binary systems. Estimates of the binary confusion noise suffer from several sources of astrophysical uncertainty, such as the form of the initial mass function and the star formation rate. There is also considerable uncertainty about what defines the confusion limit. Various ad-hoc rules have been proposed, such as the one source per bin rule, and the one source per three bin rule. Here information theoretic methods are used to derive a more realistic estimate for the confusion limit. It is found that the gravitational wave background becomes unresolvable when there is, on average, more than one source per eight frequency bins. This raises the best estimate for the frequency at which galactic binaries become a source of noise from 1.45 mHz to 2.54 mHz.