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

Abstract

Several proposed gravitational wave interferometers have a triangular configuration, such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA). For such a configuration one can construct a sky location independent or unique null channel insensitive to gravitational waves from all directions. We expand on earlier work and describe an extended null channel formalism applicable to interferometric data with non-identical as well as correlated noise sources between the different interferometers. Two examples are shown to illustrate the formalism in the context of the Einstein Telescope. Finally we highlight future research needed to transition from the mathematical formalism described here to a framework in which the formalism can be used to estimate the noise power spectral densities of the observing gravitational-wave interferometers.

Stochastic gravitational wave background: Methods and implications

“…The null channel can also be used as a tool to understand the levels of correlated noise between the different detectors as was investigated by a recent study [193].…”

Impact of correlated seismic and correlated Newtonian noise on the Einstein Telescope

“…11 Finally, one can also investigate the possibility of using the null channel as a tool to estimate correlated noise. A recent paper [60] proposes a formalism to estimate the ETs noise PSD which also gives insight in the cross-correlated noise terms. However, more work has to be done to understand its efficiency in scenario's with realistic correlated noise sources, such as the seismic and Newtonian noise as presented here.…”