Updated constraints on interacting dark energy: A comprehensive analysis using multiple CMB probes, DESI DR2, and supernovae observations

TL;DR

The paper evaluates whether interactions between dark energy and dark matter are favored by current cosmological data. Using DESI DR2 BAO, multiple CMB probes (ACT, SPT, Planck, WMAP), and SN samples (PantheonPlus, DESY5), it tests four IDE models with different Q forms and uses a stable perturbation framework (ePPF) with Bayesian model comparison. The main finding is that IDE models with Q proportional to ρ_de, especially Q = β H_0 ρ_de (IΛCDM3), are preferred by several data combinations, with evidence strengthened by SPT data and weakened by PantheonPlus SN data. However, results also highlight potential SN-calibration systematics and emphasize that forthcoming data from CMB-S4, LSST, Euclid, and future DESI releases are needed for a robust, definitive conclusion.

Abstract

Recent DESI baryon acoustic oscillation (BAO) measurements, combined with Planck cosmic microwave background (CMB) data and DESY5 type Ia supernova (SN) data, indicate a significant deviation from $Λ$CDM, which seems to suggest that this deviation can be explained by an interaction between dark energy and dark matter. In this work, we perform a comprehensive analysis by utilizing the latest DESI DR2 BAO data in conjunction with CMB data from ACT, SPT, Planck, and WMAP, along with SN data from PantheonPlus and DESY5. We consider four interacting dark energy (IDE) models with different forms of the interaction term $Q$. Our analysis indicates that CMB experiments other than Planck enhance the evidence for an interaction in the IDE models with $Q \propto ρ_{\rm de}$. In particular, when using the SPT+DESI+DESY5 data, the IDE model with $Q = βH_0 ρ_{\rm de}$ gives $β= -0.4170 \pm 0.1220$, with a deviation from zero reaching $3.4σ$ level. When replacing DESY5 with PantheonPlus, this deviation weakens to $2.1σ$ level, but remains relatively significant. Furthermore, the Bayes factors of the IDE model with $Q = βH_0 ρ_{\rm de}$ are positive in all cases, providing a moderate-to-strong preference over $Λ$CDM. Overall, our comprehensive analysis clearly suggests that the IDE models with $Q \propto ρ_{\rm de}$ (especially, $Q = βH_0 ρ_{\rm de}$) provide strong evidence supporting the existence of interaction and are more preferred by the current cosmological data.

Figures (3)

• Figure 1: Two-dimensional marginalized contours ($1\sigma$ and $2\sigma$ confidence levels) in the $H_0$--$\beta$ plane by using the Planck+DESI+DESY5, ACT+DESI+DESY5, SPT+DESI+DESY5, Planck+DESI+PantheonPlus, ACT+DESI+PantheonPlus, and SPT+DESI+PantheonPlus data in the I$\Lambda$CDM1, I$\Lambda$CDM2, I$\Lambda$CDM3, and I$\Lambda$CDM4 models.
• Figure 2: Two-dimensional marginalized contours ($1\sigma$ and $2\sigma$ confidence levels) in the $H_0$--$\beta$ plane by using the ACT+WMAP+DESI+DESY5, SPT+WMAP+DESI+DESY5, ACT+Planck-cut+DESI+DESY5, and SPT+Planck-cut+DESI+DESY5 data in the I$\Lambda$CDM1, I$\Lambda$CDM2, I$\Lambda$CDM3, and I$\Lambda$CDM4 models.
• Figure 3: Whisker plot of $\beta$ in the four I$\Lambda$CDM models, with the $1\sigma$ confidence level constraints for the various datasets employed in our analysis. Additionally, the figure also shows the deviation of $\beta$ relative to 0.