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arXiv · 2608.08490

Alternative LISA-TAIJI networks: polarization separation of the stochastic gravitational wave background

Gang Wang·Lang Liu
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Abstract

Stochastic gravitational-wave backgrounds (SGWBs) provide a unique opportunity to probe both unresolved astrophysical populations and fundamental physics in the early Universe. Future space-based gravitational-wave (GW) detectors, such as LISA and TAIJI, will enable cross-correlation observations that are particularly sensitive to SGWBs and their polarization content. In this work, we investigate the capabilities of two proposed LISA-TAIJI networks, LISA-TAIJIp and LISA-TAIJIm, for detecting and discriminating tensor, vector, and scalar polarization components of isotropic SGWBs. Using the cross-correlation between the two networks, we evaluate their sensitivities and signal-to-noise ratios for SGWBs containing different combinations of polarization sectors. We find that the LISA-TAIJIm configuration, which has a larger relative inclination between the two constellations, exhibits substantially weaker polarization degeneracies and significantly improved performance in separating polarization components, particularly for tensor-vector-scalar backgrounds. Fisher-matrix forecasts for power-law SGWBs show that the two configurations yield broadly comparable constraints on spectral parameters, reflecting the different roles of component separation and parameter estimation. Our results demonstrate that large-angle LISA-TAIJI networks provide a more favorable geometry for model-independent SGWB polarization measurements.

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Gang Wang, Lang Liu. 2026-08-09. Alternative LISA-TAIJI networks: polarization separation of the stochastic gravitational wave background. https://arxiv.org/abs/2608.08490

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