AI Insight
This study examines a coupled dark energy model where dark matter interacts with a scalar field through mass variation, using the latest cosmological data including DESI baryon acoustic oscillations, Planck cosmic microwave background measurements, and Type Ia supernovae observations. The analysis finds modest evidence for coupling (with coupling parameter |β| around 0.03), excluding zero coupling at approximately 95% confidence level, and shows the model can explain apparent phantom divide crossing in dark energy equation of state. Results remain consistent across different scalar field potentials and supernova datasets, with no significant asymmetry found between positive and negative coupling values.
Why it matters
Understanding the interaction between dark matter and dark energy could fundamentally revise our model of cosmic evolution and explain the accelerated expansion of the universe through mechanisms beyond a simple cosmological constant. These constraints help narrow the parameter space for fifth force interactions that could be tested through future precision cosmology surveys.
Understand the Science
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: We investigate the current viability of a well-known coupled dark energy scenario in which cold dark matter (DM) interacts with a spin-0 dark energy component through a non-trivial field dependence of the DM mass. This ultra-light scalar mediates a fifth force between DM particles, which can leave signatures on cosmological scales. We use state-of-the-art data on the cosmic microwave background from Planck’s CamSpec likelihood, baryon acoustic oscillations from the second DESI data release as well as the supernovae of Type Ia (SNIa) from Pantheon+ and DES-Dovekie. We perform the analysis considering both a flat potential and a Peebles-Ratra (PR) potential for the scalar field in order to assess the impact of the potential slope on the fitting performance of the model. While for a constant potential the scalar field dynamics is insensitive to the sign of the coupling parameter $beta$, the PR potential breaks the existing symmetry in the solutions at late times and could induce a difference at the phenomenological level between positive and negative values. We study for the first time if it is actually the case, finding no important asymmetry in the fitting results. In the light of the aforesaid datasets, we find in all cases a peak at $|beta|sim 0.03$ – less pronounced than reported in some recent works -, excluding the no-coupling scenario at $sim 95%$ CL at most. The model is able to explain an effective crossing of the phantom divide, with the equation-of-state parameter lying within the $2sigma$ bands of model-agnostic reconstructions. Our results are very robust under changes in the SNIa sample used in the analysis and is not significantly altered when we replace a constant potential with the PR one, although the latter is crucial to produce the aforesaid crossing. In passing, we also provide constraints obtained with the PR potential in the uncoupled case.