Year: 2026
Type: article
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 $β$, 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 $|β|\sim 0.03$ - 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 $2σ$ 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.
DOI: 10.1103/x8kc-zqzl
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: “la Caixa” Foundation, European Commission, European Cooperation in Science and Technology, Deutsche Forschungsgemeinschaft, Generalitat de Catalunya, Ministerio de Ciencia e Innovación, Universitat de Barcelona, Horizon 2020 Framework Programme, Institut de Ciències del Cosmos, H2020 Marie Skłodowska-Curie Actions
Awards: G1040666699, G1255325603, Junior Leader la Caixa Postdoctoral Fellowship Programme: Shaping the new generation of leaders in research, G1923596229, G225231157, G3068915072, G3261693824, G3522231704, Junior Leader la Caixa Postdoctoral Fellowship Programme: Shaping the new generation of leaders in research, G4117354703, G4249909660, G4993383890, G5505639174, G6418212698, G6526081583, EXC 2181: STRUKTUREN: Emergenz in Natur, Mathematik und komplexen Daten, G7731791180, G7915813472, G7944718603
OpenAlex ID: W7171692859