Reanalyzing DESI DR1: 1. $Λ$CDM Constraints from the Power Spectrum and Bispectrum
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2025
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| author | Chudaykin, Anton Ivanov, Mikhail M. Philcox, Oliver H. E. |
| author_facet | Chudaykin, Anton Ivanov, Mikhail M. Philcox, Oliver H. E. |
| contents | We present the first independent re-analysis of the galaxy clustering data from DESI Data Release 1, utilizing an effective field theory full-shape model. We analyze the power spectra and bispectra of the public catalogs using a custom-built pipeline based on window-deconvolved quasi-optimal estimators, accounting for a number of systematic effects. Compared to the official collaboration analysis, we add the galaxy power spectrum hexadecapole and the bispectrum monopole, and also introduce a novel stochastic estimator for fiber collisions, which facilitates robust bispectrum analyses. As a first application, we perform a full-shape analysis of the DESI power spectra and bispectra in the context of the standard cosmological model, $Λ$CDM. Using external priors on the physical baryon density and the primordial power spectrum tilt, we constrain the matter density fraction to $Ω_m=0.284\pm 0.011$, the Hubble constant to $H_0=70.7\pm 1.1$ km/s/Mpc, and the mass fluctuation amplitude to $σ_8=0.811\pm 0.030$. The bispectrum sharpens constraints on $σ_8$ and $Ω_m$ by $\approx 10\%$ and shifts $Ω_m$ by $\approx 1σ$ towards the \textit{Planck} $Λ$CDM value. Combining our full-shape likelihood with the official DESI DR2 BAO measurements, cosmological parameters shift further towards the \textit{Planck} values, with $Ω_m=0.296\pm 0.007$, $H_0=68.8\pm 0.6$ km/s/Mpc, $σ_8=0.818\pm 0.029$ (with tighter constraints obtained in joint analyses). Similar results are obtained in a joint analysis with DR1 BAO, accounting for the cross-covariance. Finally, the bispectrum data improves measurements of quadratic bias parameters, which are consistent with predictions from halo occupation distribution models. Our work highlights the importance of higher-order statistics and sets the stage for upcoming full-shape analyses of non-minimal cosmological models. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_13433 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Reanalyzing DESI DR1: 1. $Λ$CDM Constraints from the Power Spectrum and Bispectrum Chudaykin, Anton Ivanov, Mikhail M. Philcox, Oliver H. E. Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory We present the first independent re-analysis of the galaxy clustering data from DESI Data Release 1, utilizing an effective field theory full-shape model. We analyze the power spectra and bispectra of the public catalogs using a custom-built pipeline based on window-deconvolved quasi-optimal estimators, accounting for a number of systematic effects. Compared to the official collaboration analysis, we add the galaxy power spectrum hexadecapole and the bispectrum monopole, and also introduce a novel stochastic estimator for fiber collisions, which facilitates robust bispectrum analyses. As a first application, we perform a full-shape analysis of the DESI power spectra and bispectra in the context of the standard cosmological model, $Λ$CDM. Using external priors on the physical baryon density and the primordial power spectrum tilt, we constrain the matter density fraction to $Ω_m=0.284\pm 0.011$, the Hubble constant to $H_0=70.7\pm 1.1$ km/s/Mpc, and the mass fluctuation amplitude to $σ_8=0.811\pm 0.030$. The bispectrum sharpens constraints on $σ_8$ and $Ω_m$ by $\approx 10\%$ and shifts $Ω_m$ by $\approx 1σ$ towards the \textit{Planck} $Λ$CDM value. Combining our full-shape likelihood with the official DESI DR2 BAO measurements, cosmological parameters shift further towards the \textit{Planck} values, with $Ω_m=0.296\pm 0.007$, $H_0=68.8\pm 0.6$ km/s/Mpc, $σ_8=0.818\pm 0.029$ (with tighter constraints obtained in joint analyses). Similar results are obtained in a joint analysis with DR1 BAO, accounting for the cross-covariance. Finally, the bispectrum data improves measurements of quadratic bias parameters, which are consistent with predictions from halo occupation distribution models. Our work highlights the importance of higher-order statistics and sets the stage for upcoming full-shape analyses of non-minimal cosmological models. |
| title | Reanalyzing DESI DR1: 1. $Λ$CDM Constraints from the Power Spectrum and Bispectrum |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2507.13433 |