Do DESI-DR2 BAO data imply a coupling of dark matter and dark energy?
Abstract
We revisit an interacting dark matter (DM) -- dark energy (DE) model characterized by the interaction function Q = Γρx, where Γ is a constant coupling parameter and ρx is the energy density of DE. This type of interaction is independent of the Hubble rate or other external parameters, but depends only on the fundamental properties of DE, such as its equation of state (EoS), wx. We pay special attention to wx and study three distinct interacting scenarios distinguished by the nature of wx, i.e. wx =−1 (when DE corresponds to the vacuum energy), wx < −1 (when DE has a phantom behavior), and wx > −1 (quintessential DE). We constrain all of them using the most recent cosmological datasets, including CMB from Planck 2018, BAO from DESI DR2, and three compilations of SNIa (PantheonPlus, Union3, and DES-Dovekie). Our analyses reveal that evidence of interaction is supported in scenarios with wx =−1 and wx < −1 when all three datasets are combined, but from the Bayesian evidence analysis, ΛCDM remains favored over these interacting scenarios. Regarding the S8 parameter, when wx > −1, this interacting scenario leads to mildly lower estimates across all datasets.
Versions
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BibTeX
@misc{yang2026desidr2,
title = {{Do DESI-DR2 BAO data imply a coupling of dark matter and dark energy?}},
author = {Weiqiang Yang and Sibo Zhang and Dinorah Barbosa and Marco Antonio Alvarez and Supriya Pan and Leila Graef},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05660},
eprint = {2609.05660},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05660},
}
RIS
TY - UNPB
TI - Do DESI-DR2 BAO data imply a coupling of dark matter and dark energy?
AU - Weiqiang Yang
AU - Sibo Zhang
AU - Dinorah Barbosa
AU - Marco Antonio Alvarez
AU - Supriya Pan
AU - Leila Graef
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.05660
UR - https://arxiv.org/abs/2609.05660
AB - We revisit an interacting dark matter (DM) -- dark energy (DE) model characterized by the interaction function Q = Γρ_x, where Γ is a constant coupling parameter and ρ_x is the energy density of DE. This type of interaction is independent of the Hubble rate or other external parameters, but depends only on the fundamental properties of DE, such as its equation of state (EoS), w_x. We pay special attention to w_x and study three distinct interacting scenarios distinguished by the nature of w_x, i.e. w_x =−1 (when DE corresponds to the vacuum energy), w_x < −1 (when DE has a phantom behavior), and w_x > −1 (quintessential DE). We constrain all of them using the most recent cosmological datasets, including CMB from Planck 2018, BAO from DESI DR2, and three compilations of SNIa (PantheonPlus, Union3, and DES-Dovekie). Our analyses reveal that evidence of interaction is supported in scenarios with w_x =−1 and w_x < −1 when all three datasets are combined, but from the Bayesian evidence analysis, ΛCDM remains favored over these interacting scenarios. Regarding the S_8 parameter, when w_x > −1, this interacting scenario leads to mildly lower estimates across all datasets.
ER -