A study of dark matter-dark energy interaction under the DESI DR2 data constraint

TL;DR

This work develops a field-theoretic cosmology (QCDM) where dark matter and dark energy are interacting scalar fields, deriving the full background and perturbation dynamics without ad hoc continuity equations. It identifies a strong-coupling regime that transits from thawing to scaling-freezing in the dark energy equation of state, which DESI DR2 disfavors, and a weak-coupling regime that yields a mildly evolving $w(a)$ well described by a fitted form and consistent with DESI constraints. By performing a joint analysis with Planck, DESI DR2, and SN data using CLASS and Cobaya, the authors obtain stringent upper limits on the coupling $\lambda$ (up to $\lambda \lesssim 10^{-3}$ to $10^{-5.7}$ depending on the data) and show that the model only modestly alleviates the $H_0$ tension while keeping $S_8$ in agreement with KiDS-Legacy. Overall, ΛCDM remains favored by the information criterion, but the QCDM framework demonstrates a viable path to incorporate an evolving dark energy component via a field-theoretic DM-DE interaction.

Abstract

While $Λ$CDM provides a good fit to cosmological data, it fails to address many of the outstanding questions in contemporary cosmology. Chief among these are the Hubble tension and the apparent dynamical nature of dark energy as inferred from the recent DESI DR2 analysis. In this work, we analyze a field-theoretic description of cosmology where both dark energy and dark matter are interacting spin zero fields. We give a thorough study of a wide range of the interaction strength and demonstrate the effect on the dark energy equation of state and the Hubble tension. Using the recent cosmological data, we extract constraints on cosmological parameters including the free parameters of the model.

Figures (6)

• Figure 1: Plot of the evolution of the equations of state (EoS) of DM and DE (left) and a time-average over the oscillations in $w_\phi$ (right panel). The DM EoS, $w_\chi$, is being averaged over in both panels after a short period of oscillations. The color code correspond to different values of $\phi_{\rm ini}$ and $\mu^4$ in the presence of DM-DE interaction, expressed in standard CLASS units of $m_{\rm pl}$ and $m_{\rm pl}^2/\mathrm{Mpc}^2$, respectively. Figure is adapted from ref. Aboubrahim:2024cyk.
• Figure 2: The evolution of $w_\phi$ as a function of the redshift $z$ is shown for five choices of the interaction strength $\lambda$. The solid curves display the QCDM predictions, while the dashed curves provide fits using Eq. (\ref{['fit']}) together with the corresponding $1\sigma$ uncertainty bands. For all parameter choices, the DE equation of state exhibits a transition induced by $\lambda$, evolving from a thawing behavior at higher redshift to a scaling-freezing behavior at lower redshift. Figure is adapted from ref. Aboubrahim:2024cyk.
• Figure 3: The evolution of the DE equation of state in the narrow interval $0.1<a<1$ for the case of no interaction (dashed curves) and the case of DM-DE interaction (solid curves). The colors of each curve correspond to a choice of $(F,\phi_{\rm ini})$ as indicated in the figure legend. Both $F$ and $\phi_{\rm ini}$ are in units of $m_{\rm pl}$. The blue and green bands are the $1\sigma$ regions from DESI's interpretations of their data based on the $w_0 w_a$CDM and $w$CDM models, respectively. Figure is adapted from ref. Aboubrahim:2024cyk.
• Figure 4: Scatter plots in the $w_0$-$w_a$ plane are shown overlaid on the DESI DR2 posterior contours with the upper bound on $\log\lambda$ imposed for each data set. The left panel uses the Hubble parameter $H_0$ as the color scale, while the right panel displays $\log\lambda$. The model yields parameter points that fall within the $1\sigma$ and $2\sigma$ posterior regions of the considered data sets. Figure is adapted from ref. Aboubrahim:2024cyk.
• Figure 5: The two-dimensional marginalized contours at the 68% and 95% confidence levels are shown for the DM-DE coupling strength versus $H_0$ (left panel) and versus $S_8$ (right panel). In the left panel, the gray bands indicate the SH0ES Riess:2021jrx measurement, $H_0=73.04\pm 1.04~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, while in the right panel they represent the KiDS-Legacy Wright:2025xka constraint, $S_8=0.815^{+0.016}_{-0.021}$. Figure is adapted from ref. Aboubrahim:2024cyk.