Detecting a stochastic gravitational wave background with the Laser Interferometer Space Antenna

TL;DR

This paper explores methods for detecting a stochastic gravitational wave background with LISA by optimizing cross-correlation and Sagnac interferometry techniques to distinguish signals from noise.

Contribution

It derives the optimal orbital alignment for LISA detector pairs and provides the first analytic sensitivity curve for the Sagnac method.

Findings

Optimal orbital configuration for detector cross-correlation

Analytic sensitivity curve for Sagnac interferometer

Enhanced methods for separating gravitational wave background from noise

Abstract

The random superposition of many weak sources will produce a stochastic background of gravitational waves that may dominate the response of the LISA (Laser Interferometer Space Antenna) gravitational wave observatory. Unless something can be done to distinguish between a stochastic background and detector noise, the two will combine to form an effective noise floor for the detector. Two methods have been proposed to solve this problem. The first is to cross-correlate the output of two independent interferometers. The second is an ingenious scheme for monitoring the instrument noise by operating LISA as a Sagnac interferometer. Here we derive the optimal orbital alignment for cross-correlating a pair of LISA detectors, and provide the first analytic derivation of the Sagnac sensitivity curve.