Cosmological inference from a joint DESI DR1 full-shape power spectrum and bispectrum analysis
Abstract
The galaxy bispectrum directly probes the non-linear gravitational evolution of large-scale structure (LSS) and can break parameter degeneracies that remain in power-spectrum analyses. We present a joint full-shape cosmological analysis of three luminous red galaxy (LRG) redshift bins and the quasar (QSO) sample from the first Data Release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We model the redshift-space power spectrum at one loop and the tree-level bispectrum within the Effective Field Theory of LSS. The bispectrum is decomposed in the Tripolar Spherical Harmonics basis, for which the convolution with the survey window function can be formulated as a direct linear transformation of the theoretical multipoles. Our power-spectrum constraints are in good agreement with the official DESI DR1 full-modelling results. We investigate the impact of including the bispectrum in the inference, finding that the monopole substantially improves the constraints on the cold dark matter density and amplitude of matter fluctuations by 9-18% and 8-20%, respectively, in the individual-tracer analyses. The corresponding reductions are 15% and 10% for the combined LRG sample, and 6% and 4% when all tracers are combined. In a restricted test using the first LRG bin, the bispectrum quadrupole changes the marginalised uncertainties by only a few percent. Extending the analysis to w0waCDM substantially broadens the cosmological posteriors, while the bispectrum produces only a mild change in the allowed dark-energy parameter region, which remains sensitive to the adopted prior ranges. Our results demonstrate the potential of higher-order clustering statistics to improve cosmological constraints, while providing a framework for incorporating the bispectrum into full-shape analyses of current and future spectroscopic galaxy surveys.
Related
- Cosmological constraints from the DESI DR1 Bispectrum Full-Shape and DR2 BAO
- Dark Energy Constraints and Joint Cosmological Inference from Mutually Inconsistent Observations
- A Gaussian Covariance Matrix for Joint Pre- and Post-Reconstruction Full-Shape Power Spectrum Analysis
- Euclid preparation. CXV. Galaxy power spectrum and bispectrum modelling
- Wedge-avoidance Fisher Forecasts for Primordial Features from Dark-Ages 21-cm Power Spectrum and Bispectrum
BibTeX
@misc{guandalin2026cosmological,
title = {{Cosmological inference from a joint DESI DR1 full-shape power spectrum and bispectrum analysis}},
author = {Caroline Guandalin and Prakhar Bansal and Pedro Carrilho and Alejandro Aviles and Mike Wang and Marcos Pellejero-Ibañez and Aaditya Sarma and Jaide Swanson and Marco Bonici and Florian Beutler and Arnaud de Mattia and Hee-Jong Seo},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.01836},
eprint = {2610.01836},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05785899v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Cosmological inference from a joint DESI DR1 full-shape power spectrum and bispectrum analysis
AU - Caroline Guandalin
AU - Prakhar Bansal
AU - Pedro Carrilho
AU - Alejandro Aviles
AU - Mike Wang
AU - Marcos Pellejero-Ibañez
AU - Aaditya Sarma
AU - Jaide Swanson
AU - Marco Bonici
AU - Florian Beutler
AU - Arnaud de Mattia
AU - Hee-Jong Seo
PY - 2026
DA - 2026/10/01
PB - HAL
DO - 10.48550/arxiv.2610.01836
UR - https://hal.science/hal-05785899v1
AB - The galaxy bispectrum directly probes the non-linear gravitational evolution of large-scale structure (LSS) and can break parameter degeneracies that remain in power-spectrum analyses. We present a joint full-shape cosmological analysis of three luminous red galaxy (LRG) redshift bins and the quasar (QSO) sample from the first Data Release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We model the redshift-space power spectrum at one loop and the tree-level bispectrum within the Effective Field Theory of LSS. The bispectrum is decomposed in the Tripolar Spherical Harmonics basis, for which the convolution with the survey window function can be formulated as a direct linear transformation of the theoretical multipoles. Our power-spectrum constraints are in good agreement with the official DESI DR1 full-modelling results. We investigate the impact of including the bispectrum in the inference, finding that the monopole substantially improves the constraints on the cold dark matter density and amplitude of matter fluctuations by 9-18% and 8-20%, respectively, in the individual-tracer analyses. The corresponding reductions are 15% and 10% for the combined LRG sample, and 6% and 4% when all tracers are combined. In a restricted test using the first LRG bin, the bispectrum quadrupole changes the marginalised uncertainties by only a few percent. Extending the analysis to w_0w_aCDM substantially broadens the cosmological posteriors, while the bispectrum produces only a mild change in the allowed dark-energy parameter region, which remains sensitive to the adopted prior ranges. Our results demonstrate the potential of higher-order clustering statistics to improve cosmological constraints, while providing a framework for incorporating the bispectrum into full-shape analyses of current and future spectroscopic galaxy surveys.
ER -