Preference for evolving dark energy in light of the galaxy bispectrum
8 affiliations
- 1CAS Key Laboratory for Research in Galaxies and Cosmology, School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026,
- 2Deep Space Exploration Laboratory, Hefei 230088,
- 3Department of Astronomy, School of Physical Sciences, University of Science and Technology of China Hefei, Anhui 230026,
- 4Laboratoire Univers & Particules de Montpellier, CNRS & Université de Montpellier, 34095 Montpellier,
- 5LUPM - Laboratoire Univers et Particules de Montpellier (Place Eugène Bataillon - CC 72 34095 Montpellier Cédex 05 - France)
- 6Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano, 20133 Milan,
- 7Institut für Theoretische Physik, ETH Zürich, 8093 Zürich,
- 8Institute for Particle Physics and Astrophysics, ETH Zürich, 8093 Zürich,
Abstract
We analyse pre-DESI clustering data using a dark energy equation of state w ( z ) parametrised by ( w 0 , w a ), finding a 2.8-3.9 σ preference for evolving dark energy over the cosmological constant Λ when combined with cosmic microwave background data from Planck and supernova data from Pantheon+, Union3, or DESY5. Our constraints, consistent with DESI Y1 results, are derived from the power spectrum and bispectrum of SDSS/BOSS galaxies using the Effective Field Theory of Large Scale Structure (EFTofLSS) at one loop. The evidence, estimated as the Gaussian-equivalent significance from the Δχ 2 -statistics to ( w 0 , w a ) = (-1, 0) for two degrees of freedom, remains robust across analysis variations but disappears without the one-loop bispectrum. When combining DESI baryon acoustic oscillations with BOSS full-shape data, while marginalising over the sound horizon in the latter to partially mitigate potential correlations, the significance increases to 3.7-4.4 σ , depending on the supernova dataset. Using instead a data-driven reconstruction of w ( z ), we show that deviations from Λ can be observed at multiple redshifts, though at a low level of significance: only when imposing the specific parametrisation implied by ( w 0 , w a ) the above evidence emerges. In addition, our findings are interpreted within the Effective Field Theory of Dark Energy (EFTofDE), from which we explicitly track the non-standard time evolution in EFTofLSS predictions. For perturbatively stable theories in the w < -1 regime, the preference for w 0 w a CDM persists notably in the clustering limit ( c s 2 → 0) when higher-derivative corrections are present.
Related
- Euclid preparation. CXV. Galaxy power spectrum and bispectrum modelling
- Detection of the Galaxy--Galaxy--Temperature Skewed Bispectrum
- Analytic bispectrum covariance for galaxy survey cosmology
- Constraints on Primordial Oscillatory Features from the Power Spectrum and Bispectrum of Redshift-Space Galaxy Clustering in DESI DR1
- Cross-Bispectrum Constraints from HI Intensity Mapping and Galaxy Surveys
BibTeX
@article{lu2026preference,
title = {{Preference for evolving dark energy in light of the galaxy bispectrum}},
author = {Zhiyu Lu and Théo Simon and Pierre Zhang},
journal = {Journal of Cosmology and Astroparticle Physics},
year = {2026},
month = oct,
doi = {10.1088/1475-7516/2026/10/052},
url = {https://doi.org/10.1088/1475-7516/2026/10/052},
note = {CC BY},
}
RIS
TY - JOUR
TI - Preference for evolving dark energy in light of the galaxy bispectrum
AU - Zhiyu Lu
AU - Théo Simon
AU - Pierre Zhang
PY - 2026
DA - 2026/10/01
JO - Journal of Cosmology and Astroparticle Physics
DO - 10.1088/1475-7516/2026/10/052
UR - https://doi.org/10.1088/1475-7516/2026/10/052
AB - We analyse pre-DESI clustering data using a dark energy equation of state w ( z ) parametrised by ( w 0 , w a ), finding a 2.8-3.9 σ preference for evolving dark energy over the cosmological constant Λ when combined with cosmic microwave background data from Planck and supernova data from Pantheon+, Union3, or DESY5. Our constraints, consistent with DESI Y1 results, are derived from the power spectrum and bispectrum of SDSS/BOSS galaxies using the Effective Field Theory of Large Scale Structure (EFTofLSS) at one loop. The evidence, estimated as the Gaussian-equivalent significance from the Δχ 2 -statistics to ( w 0 , w a ) = (-1, 0) for two degrees of freedom, remains robust across analysis variations but disappears without the one-loop bispectrum. When combining DESI baryon acoustic oscillations with BOSS full-shape data, while marginalising over the sound horizon in the latter to partially mitigate potential correlations, the significance increases to 3.7-4.4 σ , depending on the supernova dataset. Using instead a data-driven reconstruction of w ( z ), we show that deviations from Λ can be observed at multiple redshifts, though at a low level of significance: only when imposing the specific parametrisation implied by ( w 0 , w a ) the above evidence emerges. In addition, our findings are interpreted within the Effective Field Theory of Dark Energy (EFTofDE), from which we explicitly track the non-standard time evolution in EFTofLSS predictions. For perturbatively stable theories in the w < -1 regime, the preference for w 0 w a CDM persists notably in the clustering limit ( c s 2 → 0) when higher-derivative corrections are present.
SN - 1475-7508
SN - 1475-7516
ER -