Coherent injection of magnetic noise and its impact on gravitational-wave searches

TL;DR

This paper demonstrates the first coherent magnetic noise injection between LIGO detectors, assessing its impact on gravitational-wave searches and testing noise subtraction methods like Wiener filtering.

Contribution

It introduces a novel broadband magnetic noise injection method and evaluates noise projection and subtraction techniques for gravitational-wave detectors.

Findings

Wiener filtering effectively reduces magnetic noise contamination.

Coherent magnetic noise injection impacts gravitational-wave data analysis.

The study provides a new testing framework for noise mitigation in gravitational-wave detection.

Abstract

Correlated noise sources, particularly magnetic noise, form a risk to future gravitational-wave searches aimed at detecting the gravitational-wave background. Potential noise contamination is investigated by making noise projections which typically rely on an accurate measurement of the coupling strength of the noise to the detector. To make these projections, we inject, for the first time, broadband, coherent magnetic noise between two gravitational-wave detectors, LIGO Hanford and LIGO Livingston, separated by several thousands of kilometers. We describe the noise injection as well as its impact on the analysis pipelines and investigate the accuracy of noise projection techniques used in the past decade. Finally, we present a proof-of-concept demonstration of noise subtraction using Wiener filtering, while also highlighting potential risks associated with this method. This unique data set with correlated noise caused by magnetic field fluctuations in two gravitational-wave detectors, as well as in an array of witness sensors, provides an excellent testing ground for additional future studies. Ultimately, this study demonstrates that Wiener filtering is effective and can be applied in the eventual detection of the gravitational-wave background by the LIGO-Virgo-KAGRA Collaboration.