Utilizing the null stream of the Einstein Telescope

TL;DR

The paper explores the use of the Einstein Telescope's null stream for improved noise modeling, glitch elimination, and unbiased noise spectrum estimation, enhancing gravitational-wave data analysis capabilities.

Contribution

It demonstrates the practical application of the Einstein Telescope's null stream for noise mitigation and spectrum estimation without prior glitch models, addressing future detector challenges.

Findings

Null stream can eliminate transient glitches effectively.

Null stream enables unbiased noise spectrum estimation.

Techniques are computationally efficient and model-independent.

Abstract

Among third-generation ground-based gravitational-wave detectors proposed for the next decade, the Einstein Telescope provides a unique kind of null stream $\unicode{x2014}$ the signal-free linear combination of data $\unicode{x2014}$ that enables otherwise inaccessible tests of the noise models. We project and showcase challenges in modeling the noise in the 2030s and how it will affect the performance of third-generation detectors. We find that the null stream of the Einstein Telescope is capable of eliminating transient detector glitches that are known to limit current gravitational-wave searches. The techniques we discuss are computationally efficient and do not require a priori knowledge about glitch models. Furthermore, we show how the null stream can be used to provide an unbiased estimation of the noise power spectrum necessary for online and offline data analyses even with multiple loud signals in the band. We overview other approaches to utilizing the null stream. Finally, we comment on the limitations and future challenges of null-stream analyses for the Einstein Telescope and arbitrary detector networks.