Constraints on interacting dark energy with a constant equation of state in light of DESI DR2: The role of the interaction term
Abstract
Recent DESI baryon acoustic oscillation (BAO) analyses suggest a preference for an evolving dark energy equation of state (EoS) that crosses the phantom divide w=−1. Interactions between dark energy and dark matter can also produce an apparent phantom-divide crossing in the effective dark energy EoS. In this work, we investigate interacting dark energy (IDE) models with a constant EoS parameter w, using cosmic microwave background (CMB) observations from Planck, ACT, and SPT, DESI DR2 BAO measurements, and type Ia supernova data from PantheonPlus, DES-Dovekie, and DESY5. We consider four typical forms of the interaction term Q. Our results show that the IDE models with Q∝ρde generally exhibit a stronger preference for nonzero dark-sector interactions. In particular, for the CMB+DESI+DES-Dovekie data, the IDE model with Q=βH0ρde yields β=−2.52+0.80−0.54 and w=−1.510+0.170−0.120, corresponding to deviations from β=0 and w=−1 at the 3.2σ and 3.0σ levels, respectively. Interestingly, the effective EoS of the IDE model with Q=βH0ρde exhibits a redshift evolution resembling that of the w0waCDM model, crossing the phantom divide. Bayesian evidence further indicates that this IDE model is favored over ΛCDM and the other three IDE models. Our analysis helps identify which interaction forms better account for current cosmological observations.
Related
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BibTeX
@misc{li2026constraints,
title = {{Constraints on interacting dark energy with a constant equation of state in light of DESI DR2: The role of the interaction term}},
author = {Zhao-Yu Li and Tian-Nuo Li and Guo-Hong Du and Sheng-Han Zhou and Yun-He Li and Jing-Fei Zhang and Xin Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.30784},
eprint = {2610.30784},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.30784},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Constraints on interacting dark energy with a constant equation of state in light of DESI DR2: The role of the interaction term
AU - Zhao-Yu Li
AU - Tian-Nuo Li
AU - Guo-Hong Du
AU - Sheng-Han Zhou
AU - Yun-He Li
AU - Jing-Fei Zhang
AU - Xin Zhang
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.30784
UR - https://arxiv.org/abs/2610.30784
AB - Recent DESI baryon acoustic oscillation (BAO) analyses suggest a preference for an evolving dark energy equation of state (EoS) that crosses the phantom divide w=−1. Interactions between dark energy and dark matter can also produce an apparent phantom-divide crossing in the effective dark energy EoS. In this work, we investigate interacting dark energy (IDE) models with a constant EoS parameter w, using cosmic microwave background (CMB) observations from Planck, ACT, and SPT, DESI DR2 BAO measurements, and type Ia supernova data from PantheonPlus, DES-Dovekie, and DESY5. We consider four typical forms of the interaction term Q. Our results show that the IDE models with Q∝ρ_de generally exhibit a stronger preference for nonzero dark-sector interactions. In particular, for the CMB+DESI+DES-Dovekie data, the IDE model with Q=βH_0ρ_de yields β=−2.52^+0.80_−0.54 and w=−1.510^+0.170_−0.120, corresponding to deviations from β=0 and w=−1 at the 3.2σ and 3.0σ levels, respectively. Interestingly, the effective EoS of the IDE model with Q=βH_0ρ_de exhibits a redshift evolution resembling that of the w_0w_aCDM model, crossing the phantom divide. Bayesian evidence further indicates that this IDE model is favored over ΛCDM and the other three IDE models. Our analysis helps identify which interaction forms better account for current cosmological observations.
ER -