Cosmological constraints from the DESI DR1 Bispectrum Full-Shape and DR2 BAO

arXiv:2606.23936 · astro-ph.CO · Submitted 2026-06-22 · Read on arXiv

D. Forero-Sánchez, S. Novell-Masot, H. Gil-Marín, L. Verde, J. Aguilar, S. Ahlen, D. Bianchi, A. Brodzeller, D. Brooks, F. J. Castander, S. Cole, A. de la Macorra, J. Della Costa, Biprateep Dey, P. Doel, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, Satya Gontcho A Gontcho, G. Gutierrez, C. Hahn, H. K. Herrera-Alcantar, K. Honscheid, D. Huterer, M. Ishak, D. Kirkby, A. Kremin, O. Lahav, C. Lamman, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, J. A. Newman, G. Niz, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, G. Rossi, L. Samushia, E. Sanchez, D. Schlegel, M. Schubnell, J. Silber, G. Tarlé, B. A. Weaver

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astro-ph.CO

Submitted: 2026-06-22

Comments: 32 pages, 10 figures, submitted to JCAP

Code: https://github.com/cosmodesi/desilike

License: http://creativecommons.org/licenses/by/4.0/

The gist: We present cosmological constraints from the combination of DESI DR1 full-shape measurements, including for the LRG bispectrum, and DESI DR2 BAO data.

Terminology

Abstract

We present cosmological constraints from the combination of DESI DR1 full-shape measurements, including for the LRG bispectrum, and DESI DR2 BAO data. The joint analysis accounts for cross-covariance using mocks, while ShapeFit compression mitigates prior volume effects that hinder beyond- CDM analyses. In CDM, the bispectrum (P+B) shifts sigma 8 up by 1.1 sigma and S 8 by 1.2 sigma, reducing their uncertainties by 26% and 28%, respectively. For w 0w a CDM, DESI-only analyses with the bispectrum shift dark energy parameters toward CDM, staying consistent with a cosmological constant within 1 sigma. Adding CMB creates a preference for evolving dark energy: DESI+CMB (P+B) shows a 2.8 sigma deviation from CDM. Including DES-Dovekie supernovae alone reduces this to 1.6 sigma, while the full combination DESI+CMB+DES-Dovekie gives 3.1 sigma, driven primarily by the CMB. The bispectrum consistently weakens evidence for time-varying dark energy relative to power-spectrum-only analyses. The bispectrum also enhances sensitivity to massive neutrinos: in DESI-only analysis, the power-spectrum-only posterior for sum m nu is consistent with zero, whereas adding the bispectrum yields a mean of 0.26 plus or minus0.17 eV and a 95% upper limit of 0.57 eV, shifting the peak into the positive region and agreeing with oscillation lower bounds. For modified gravity, the bispectrum further constrains mu 0 = 0.12 plus or minus0.49 from DESI-only data, consistent with general relativity. Our analysis shows that accounting for cross-dataset covariances and avoiding prior volume effects yields robust constraints, with the bispectrum raising amplitude parameters and tightening their uncertainties.

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