Tackling excess noise from bilinear and nonlinear couplings in gravitational-wave interferometers

TL;DR

This paper presents improved tools for detecting and characterizing excess noise caused by nonlinear couplings in gravitational-wave interferometers, aiding in noise mitigation and sensitivity enhancement.

Contribution

It introduces advanced detection and higher-order statistics tools to analyze nonlinear couplings in LIGO data, facilitating noise identification and mitigation strategies.

Findings

Effective detection of excess noise from nonlinear couplings

Characterization of coupling frequencies using higher-order statistics

Assessment of transient noise impact on astrophysical searches

Abstract

We describe a tool we improved to detect excess noise in the gravitational wave (GW) channel arising from its bilinear or nonlinear coupling with fluctuations of various components of a GW interferometer and its environment. We also describe a higher-order statistics tool we developed to characterize these couplings, e.g., by unraveling the frequencies of the fluctuations contributing to such noise, and demonstrate its utility by applying it to understand nonlinear couplings in Advanced LIGO engineering data. Once such noise is detected, it is highly desirable to remove it or correct for it. Such action in the past has been shown to improve the sensitivity of the instrument in searches of astrophysical signals. If this is not possible, then steps must be taken to mitigate its influence, e.g., by characterizing its effect on astrophysical searches. We illustrate this through a study of the effect of transient sine-Gaussian noise artifacts on a compact binary coalescence template bank.