Probing the sign-changeable interaction between dark energy and dark matter with DESI baryon acoustic oscillations and DES supernovae data

TL;DR

This paper investigates whether the interaction between dark energy and dark matter can change sign during cosmic evolution by constraining four sign-changeable IDE models with DESI BAO, DESY5 SN, and CMB data. The authors implement a running coupling $\beta(a)=\beta_0 a+\beta_{e}(1-a)$ and compare four Q-term forms, using the extended parameterized post-Friedmann (ePPF) framework to robustly treat perturbations, and perform Bayesian model comparison against ΛCDM. They find $β_0<0$ and $β_{\rm e}>0$ at $>2\sigma$ for all models, with $β(z)$ crossing $0$ for IDE1, IDE3, and IDE4 (around $z\sim0.5$–$0.7$ and $z\sim2.0$ respectively), while IDE2 shows no sign change. Energy transfer tends to DM→DE when DM dominates and DE→DM when DE dominates for IDE1/IDE3, and IDE1/IDE3 are moderately preferred over ΛCDM (IDE3 yielding the strongest evidence, $\ln \mathcal{B}_{ij}=3.924$); IDE2 is strongly disfavored and IDE4 remains inconclusive. The results motivate future analyses with larger datasets (DESI, Euclid, LSST, CMB-S4) to sharpen these constraints on sign-changeable IDEs.

Abstract

There is a possibility of interaction between dark energy and dark matter, and this interaction may also undergo a sign change during the evolution of the universe. In this paper, we utilize the latest observational data to constrain models of a sign-changeable interaction. The data we employ, in addition to the cosmic microwave background data, also encompass the first-year baryon acoustic oscillation data from DESI and the type Ia supernova data of the full 5-year observation from DES. To achieve high generality, we investigate four interacting dark energy (IDE) models with different forms of the interaction term $Q$: (i) IDE1 with $Q = β(a)Hρ_{\rm de}$; (ii) IDE2 with $Q = β(a)Hρ_{\rm c}$; (iii) IDE3 with $Q = β(a)H_0ρ_{\rm de}$; (iv) IDE4 with $Q = β(a)H_0ρ_{\rm c}$. From the analysis, we observe that $β(z) > 0$ at early times and $β(z) < 0$ at late times, with the coupling $β(z)$ crossing the non-interacting line $β(z) = 0$ during cosmic evolution at the 2$σ$ confidence level for the IDE1, IDE3, and IDE4 models. However, for the IDE2 model, $β(z)$ remains consistently negative and does not cross $β(z) = 0$ at the 2$σ$ confidence level. Our findings indicate that the energy transfer is from dark matter to dark energy when dark matter dominates the universe, and from dark energy to dark matter when dark energy dominates, for the IDE1 and IDE3 models. Furthermore, Bayesian evidence suggests that the IDE1 and IDE3 models are moderately preferred over the $Λ$CDM model. The overall outcomes of this study clearly indicate that, based on current observational data, the sign-changeable IDE models are quite compelling and merit further attention.

Figures (3)

• Figure 1: Constraints on the cosmological parameters using the CMB+DESI+DESY5 data in the IDE1, IDE2, IDE3, and IDE4 models.
• Figure 2: Reconstructed evolutionary history of $\beta(z)$ at $1\sigma$ and $2\sigma$ confidence levels in the IDE1, IDE2, IDE3, and IDE4 models. The black dashed line in each plot represents the non-interacting line $\beta(z)=0$.
• Figure 3: Comparison of the Bayesian evidence for the IDE models and the $\Lambda$CDM model. The Bayes factor $\ln \mathcal{B}_{ij}$ (where $i$ = IDE, $j$ = $\Lambda$CDM) and its strength according to the Jeffreys scale are used to assess the preference between models, where a positive value indicates a preference for the IDE model.