Utilizing the null stream of the Einstein Telescope

Abstract

Among third-generation ground-based gravitational-wave detectors proposed for the next decade, Einstein Telescope provides a unique kind of null stream -the signal-free linear combination of data -that enables otherwise inaccessible tests of the noise models. We project and showcase challenges in modeling the noise in the 2030-s and how it will affect the performance of third-generation detectors. We find that the null stream of Einstein Telescope is capable of entirely 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 band. We overview other approaches to utilizing the null stream. Finally, we comment on the limitations and future challenges of null stream analyses for Einstein Telescope and arbitrary detector networks.

Formulation of an extended null channel formalism for a triangular gravitational wave interferometer configuration in the case of non-identical and correlated noise

“…Here we note that the sky location independent null channel has been demonstrated to give a PSD estimate in the case of ET [16] in the highly idealized scenario with no correlated noise, as well as identical noise for the three different interferometers. A more recent study has investigated the effectiveness of the null channel in the presence of noise transients, also known as glitches [29]. In the context of LISA correlated noise was considered but the noise contributions where identical to the three different interferometers [30][31][32][33][34].…”