Probing elastic interactions in the dark sector and the role of S8

Jose Beltrán Jiménez, Dario Bettoni, David Figueruelo, Florencia Anabella Teppa Pannia, Shinji Tsujikawa

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


We place observational constraints on two models within a class of scenarios featuring an elastic interaction between dark energy and dark matter that only produces momentum exchange up to first order in cosmological perturbations. The first one corresponds to a perfect-fluid model of the dark components with an explicit interacting Lagrangian, where dark energy acts as a dark radiation at early times and behaves as a cosmological constant at late times. The second one is a dynamical dark energy model with a dark radiation component, where the momentum exchange covariantly modifies the conservation equations in the dark sector. Using cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and supernovae type Ia (SnIa) data, we show that the Hubble tension can be alleviated due to the additional radiation, while the σ8 tension present in the Λ-cold-dark-matter model can be eased by the weaker galaxy clustering that occurs in these interacting models. Furthermore, we show that, while CMB+BAO+SnIa data put only upper bounds on the coupling strength, adding low-redshift data in the form of a constraint on the parameter S8 strongly favors nonvanishing values of the interaction parameters. Our findings are in line with other results in the literature that could signal a universal trend of the momentum exchange among the dark sector.

Original languageEnglish
Article number103503
JournalPhysical Review D
Issue number10
Publication statusPublished - 2021 Nov 15

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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