Dynamical dark energy in light of the DESI DR2 baryonic acoustic oscillations measurements

Understanding whether cosmic acceleration arises from a cosmological constant or a dynamical component is a central goal of cosmology, and the Dark Energy Spectroscopic Instrument (DESI) enables stringent tests with high-precision distance measurements. Here we analyse measurements of baryon acoustic oscillations in DESI Data Release 1 and Data Release 2 and consider type Ia supernovae and a distance prior for the cosmic microwave background. With the larger statistical power and wider redshift coverage of Data Release 2, the preference for dynamical dark energy does not diminish relative to Data Release 1. Using both a shape-function reconstruction and non-parametric approaches with a Horndeski-motivated correlation prior, we find that the equation of state for dark energy <i>w</i>(<i>z</i>) varies with redshift. Baryon acoustic oscillation data alone yield modest constraints, but in combination with independent supernova compilations and the prior for the cosmic microwave background, they strengthen the evidence for dynamics. A Bayesian comparison of models shows moderate support for departures from <i>Λ</i> cold dark matter (<i>Λ</i>CDM) when several degrees of freedom in <i>w</i>(<i>z</i>) are allowed, corresponding to ~3<i>σ</i> tension with <i>Λ</i>CDM (and higher for some datasets). Despite methodological differences, our results are consistent with companion DESI papers, underscoring the complementarity of the approaches. Possible systematics remain under study; forthcoming DESI, Euclid and next-generation cosmic microwave background data will provide decisive tests.

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Journal
Nature Astronomy
Published
2025-09-29
DOI
https://doi.org/10.1038/s41550-025-02669-6
Citations
27
Primary Topic
Cosmology and Gravitation Theories
Type
article
Field-Weighted Citation Impact
31.18

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article

Dynamical dark energy in light of the DESI DR2 baryonic acoustic oscillations measurements

D. Kirkby, Will J. Percival, Jean‐Paul Kneib, D. Brooks et al.
27 citations
Nature Astronomy
Cosmology and Gravitation Theories
31.18
article

Dynamical dark energy in light of the DESI DR2 baryonic acoustic oscillations measurements

D. Kirkby, Will J. Percival, Jean‐Paul Kneib, D. Brooks, Rongpu Zhou, Michael Walther, A. Muñoz-Gutiérrez, Levon Pogosian, N. Palanque‐Delabrouille, S. Nadathur, Gregory Tarlé, Gangxu Gu, Jorge L. Cervantes–Cota, Laurent Le Guillou, David Sprayberry, David J. Schlegel, Ignasi Pérez-Ràfols, Axel de la Macorra, Martin Landriau, Simone Ferraro, Lado Samushia, John A. Peacock, Shaun Cole, Marc Manera, Gaston Gutierrez, Gong‐Bo Zhao, Arman Shafieloo, Xiaoma Wang, Eusebio Sanchez, Satya Gontcho A Gontcho, Alexie Leauthaud, ChangHoon Hahn, Cheng Zhao, ENRIQUE GAZTAÑAGA, Zheng Cai, K. Koyama, Cullan Howlett, Steven P. Ahlen, Aaron Meisner, Davide Bianchi, Pauline Zarrouk, R. Miquel, John Moustakas, Arnaud de Mattia, Mustapha Ishak, Yuting Wang, Ruiyang Zhao, Hee‐Jong Seo, Robert Kehoe, Hu Zou, Graziano Rossi, Benjamin A. Weaver, P. Doel, O. Lahav, J. E. Forero-Romero, Michael Levi, T. Claybaugh, Francisco Prada
article en
27 citations

Abstract

Understanding whether cosmic acceleration arises from a cosmological constant or a dynamical component is a central goal of cosmology, and the Dark Energy Spectroscopic Instrument (DESI) enables stringent tests with high-precision distance measurements. Here we analyse measurements of baryon acoustic oscillations in DESI Data Release 1 and Data Release 2 and consider type Ia supernovae and a distance prior for the cosmic microwave background. With the larger statistical power and wider redshift coverage of Data Release 2, the preference for dynamical dark energy does not diminish relative to Data Release 1. Using both a shape-function reconstruction and non-parametric approaches with a Horndeski-motivated correlation prior, we find that the equation of state for dark energy <i>w</i>(<i>z</i>) varies with redshift. Baryon acoustic oscillation data alone yield modest constraints, but in combination with independent supernova compilations and the prior for the cosmic microwave background, they strengthen the evidence for dynamics. A Bayesian comparison of models shows moderate support for departures from <i>Λ</i> cold dark matter (<i>Λ</i>CDM) when several degrees of freedom in <i>w</i>(<i>z</i>) are allowed, corresponding to ~3<i>σ</i> tension with <i>Λ</i>CDM (and higher for some datasets). Despite methodological differences, our results are consistent with companion DESI papers, underscoring the complementarity of the approaches. Possible systematics remain under study; forthcoming DESI, Euclid and next-generation cosmic microwave background data will provide decisive tests.

Nature AstronomyVol. 9(12)
Boston University (US), Institució Catalana de Recerca i Estudis Avançats (ES), Universitat Autònoma de Barcelona (ES), Centre National de la Recherche Scientifique (FR), Fermi National Accelerator Laboratory (US), Berkeley College (US), University of Arizona (US), Lawrence Berkeley National Laboratory (US), University of Waterloo (CA), North China Electric Power University (CN), Queensland University of Technology (AU), Universidad de Los Andes (CO), The University of Texas at Dallas (US), The University of Queensland (AU), Universidad Autónoma de la Ciudad de México (MX), University of Pittsburgh (US), Southern Methodist University (US), Simon Fraser University (CA), Ilia State University (GE), Perimeter Institute (CA), University of California, Santa Cruz (US), Institute for High Energy Physics (ES), University of Milan (IT), Kansas State University (US), Durham University (GB), Chinese Academy of Sciences (CN), University of California, Irvine (US), Institut Mines-Télécom (FR), Beijing Normal University (CN), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), University of Michigan (US), Korea Astronomy and Space Science Institute (KR), Brera Astronomical Observatory (IT), Evgeni Kharadze Georgian National Astrophysical Observatory (GE), Sejong University (KR), University of Massachusetts Boston (US), Sorbonne Université (FR), National Solar Observatory (US), Institut d'Estudis Espacials de Catalunya (ES), Instituto Nacional de Investigaciones Nucleares (MX), Laboratoire d’Astrophysique de Marseille (FR), Korean Association for the Study of Intestinal Diseases (KR), Excellence Cluster Origins (DE), Institut Català de Ciències del Clima (ES), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), Royal Observatory (GB), Ohio University (US), Lickenbrock (US), Indiana Cancer Consortium (US), Institute of Space Sciences (ES), Centre for Theoretical Physics and Astrophysics (UZ), Michigan United (US), Unidades Centrales Científico-Técnicas (ES), Institut für Urheber- und Medienrecht (DE), CEA Paris-Saclay (FR), Community Science and Data Center (US), Institute of High Energy Physics (CN), UC Irvine Health (US), NSF NOIRLab (US), Universidad Insurgentes (MX), Mylan (Switzerland) (CH), Excellence Cluster Universe (DE), Las Campanas Observatory (CL), Instituto de Astrofísica de Andalucía (ES), Abiola Ajimobi Technical University Ibadan (NG), National Astronomical Observatories (CN), University of Chinese Academy of Sciences (CN), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), University College London (GB), École Polytechnique Fédérale de Lausanne (CH), University of Portsmouth (GB), The University of Tokyo (JP), Ludwig-Maximilians-Universität München (DE), Korea University of Science and Technology (KR), Universidad Nacional Autónoma de México (MX), Siena College (US), Netherlands Institute for Radio Astronomy (NL), University of California, Berkeley (US), Universitat Politècnica de Catalunya (ES), University of Edinburgh (GB), Tsinghua University (CN)
National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, Ministerio de Ciencia, Innovación y Universidades, National Natural Science Foundation of China, Chinese Academy of Sciences, Youth Innovation Promotion Association of the Chinese Academy of Sciences, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Office of Science, Science and Technology Facilities Council, Agencia Estatal de Investigación, Youth Innovation Promotion Association, Division of Astronomical Sciences, Lawrence Berkeley National Laboratory
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Cosmology and Gravitation Theories
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