https://doi.org/10.1140/epjc/s10052-025-14616-w
Regular Article - Experimental Physics
Test for LISA foreground Gaussianity and stationarity: galactic white-dwarf binaries
1
Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126, Milan, Italy
2
INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126, Milan, Italy
3
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85741, Garching, Germany
4
Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham, B15 2TT, Birmingham, UK
5
Université Lyon, Université Claude Bernard Lyon 1, CNRS, IP2I Lyon/IN2P3, UMR 5822, 69622, Villeurbanne, France
6
Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, UK
7
Kavli Institute for Cosmology, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, UK
8
Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, CB3 0WA, Cambridge, UK
a
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Received:
24
May
2025
Accepted:
6
August
2025
Published online:
20
August
2025
Upcoming space-based gravitational-wave detectors will be sensitive to millions and resolve tens of thousands of stellar-mass binary systems at mHz frequencies. The vast majority of these will be double white dwarfs in our Galaxy. The greatest part will remain unresolved, forming an incoherent stochastic foreground signal. Using state-of-the-art galactic models for the formation and evolution of binary white dwarfs and accurate LISA simulated signals, we introduce a test for foreground Gaussianity and stationarity, building on methods available for ground-based detectors. We explain the observed non-stationarity with a new analytical modulation induced by the LISA constellation motion and the intrinsic anisotropy of the source distribution. By demodulating the foreground signal, we reveal a deviation from Gaussianity in the 2–10 mHz frequency band. Our finding is crucial to design faithful data models: the proposed method serves as a diagnostic and estimation tool to flag and model deviations, respectively. Neglecting them would introduce systematic biases on individual sources and astrophysical foregrounds parameter estimation, ultimately leading to inaccurate interpretation of the LISA data.
© The Author(s) 2025
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Funded by SCOAP3.
