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Observational challenges to holographic and Ricci dark energy paradigms: Insights from ACT DR6 and DESI DR2

Peng-Ju Wu, Tian-Nuo Li, Guo-Hong Du, Xin Zhang

Abstract

Recent studies suggest that dark energy may be dynamical rather than being a mere cosmological constant $Λ$. In this work, we examine the viability of two physically well-motivated dynamical dark energy models -- holographic dark energy (HDE) and Ricci dark energy (RDE) -- by confronting them with the latest observational data, including ACT cosmic microwave background anisotropies, DESI baryon acoustic oscillations, and DESY5 supernovae. Our analysis reveals a fundamental tension between early- and late-universe constraints within both frameworks: ACT favors a quintom scenario where the dark energy equation of state evolves from $w>-1$ at early times to $w<-1$ at late times, while DESI+DESY5 exhibits a distinct preference for quintessence where $w>-1$ across cosmic evolution. Critically, the RDE model fails to provide a coherent description of cosmic evolution, as it manifests severe tensions (exceeding $10σ$ significance) between early- and late-universe parameter reconstructions. In addition, Bayesian evidence disfavors both models relative to the $Λ$CDM model. Our findings statistically exclude the original HDE and RDE models and uncover a severe discrepancy between early- and late-universe observations described by them, leading to the conclusion that the HDE and RDE models can be ruled out by current observational data.

Observational challenges to holographic and Ricci dark energy paradigms: Insights from ACT DR6 and DESI DR2

Abstract

Recent studies suggest that dark energy may be dynamical rather than being a mere cosmological constant . In this work, we examine the viability of two physically well-motivated dynamical dark energy models -- holographic dark energy (HDE) and Ricci dark energy (RDE) -- by confronting them with the latest observational data, including ACT cosmic microwave background anisotropies, DESI baryon acoustic oscillations, and DESY5 supernovae. Our analysis reveals a fundamental tension between early- and late-universe constraints within both frameworks: ACT favors a quintom scenario where the dark energy equation of state evolves from at early times to at late times, while DESI+DESY5 exhibits a distinct preference for quintessence where across cosmic evolution. Critically, the RDE model fails to provide a coherent description of cosmic evolution, as it manifests severe tensions (exceeding significance) between early- and late-universe parameter reconstructions. In addition, Bayesian evidence disfavors both models relative to the CDM model. Our findings statistically exclude the original HDE and RDE models and uncover a severe discrepancy between early- and late-universe observations described by them, leading to the conclusion that the HDE and RDE models can be ruled out by current observational data.

Paper Structure

This paper contains 5 sections, 14 equations, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. methodology
  3. Observational data
  4. Cosmological constraints
  5. Conclusion

Figures (4)

  • Figure 1: Constraints on cosmological parameters using the Planck and ACT CMB data. Left panel: Constraints on the HDE model. Right panel: Constraints on the RDE model.
  • Figure 2: Constraints on cosmological parameters using the ACT, DESI+DESY5, and ACT+DESI+DESY5 data. Left panel: Constraints on the HDE model. Right panel: Constraints on the RDE model.
  • Figure 3: The reconstructed evolution history of dark energy EoS $w$ at the $1\sigma$ and $2\sigma$ confidence levels for the HDE and RDE models, constrained by current observational data. The black dashed line denotes the cosmological constant ($w=-1$).
  • Figure 4: Graphical representation of dark energy model comparison results. The Bayes factor $\ln \mathcal{B}_{ij}$ (where $i$ denotes alternative dark energy models and $j$ the $\Lambda$CDM model) quantifies relative model evidence according to Jeffreys scale, with negative values signifying statistical preference for $\Lambda$CDM. The shaded regions from left to right represent inconclusive, weak, moderate, strong, and decisive evidence, respectively.