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

Understand

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.