Figures of merit for a stochastic gravitational-wave background measurement by LISA: implications of LISA Pathfinder noise correlations

Abstract

An important goal of the Laser Interferometer Space Antenna (LISA) is to observe a stochastic gravitational-wave background (SGWB). A study of possible correlated noise in LISA is relevant to establish limits for this future measurement. To test noise investigation methods under somewhat realistic conditions, we use the data of LISA Pathfinder (LPF). We calculate the coherence between the LPF differential acceleration of the two test-masses with magnetic fields, temperature, and micronewton cold gas thruster activity in the spacecraft. We apply our observed correlations to LISA, and estimate how the presence of such correlated noise would affect its search for a SGWB. In the context of a figure of merit, we estimate the effect of noise on the LISA SGWB search.

Stochastic gravitational wave background: Methods and implications

“…There have been several studies investigating correlated magnetic noise at the ET [158,138] as well as correlated seismic and Newtonian noise [191]. Based on LISA pathfinder data also some preliminary noise correlation studies have been performed [192]. This implies the three interferometers of the ET configuration might have many (local) correlated noise sources, which will lead to a non-negligible impact of these noise sources on the cross-correlation spectrum used in searches for a SGWB.…”

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

“…For LISA noise correlation studies resulting from the spatial environment can benefit finer noise characterisation. These noises include for example the effect of micro-thrusters, the magnetic field and the temperature variations on the test-mass system [55].…”