Structure formation simulations with momentum exchange: alleviating tensions between high-redshift and low-redshift cosmological probes

TL;DR

This paper explores dark matter-dark energy scattering models through N-body simulations, showing they can suppress density perturbations and cluster abundance, potentially resolving tensions between low-redshift and CMB cosmological constraints.

Contribution

It introduces and tests a novel dark matter-dark energy scattering model using large-scale simulations, demonstrating its effects on structure formation and tension alleviation.

Findings

Dark scattering models mildly affect large-scale structure observables.

They significantly suppress linear density perturbations.

Models help reconcile low-redshift and CMB measurements.

Abstract

Persisting tensions between the cosmological constraints derived from low-redshift probes and the ones obtained from temperature and polarisation anisotropies of the Cosmic Microwave Background -- although not yet providing compelling evidence against the $\Lambda $CDM model -- seem to consistently indicate a slower growth of density perturbations as compared to the predictions of the standard cosmological scenario. Such behavior is not easily accommodated by the simplest extensions of General Relativity, such as f(R) models, which generically predict an enhanced growth rate. In the present work we present the outcomes of a suite of large N-body simulations carried out in the context of a cosmological model featuring a non-vanishing scattering cross section between the dark matter and the dark energy fields, for two different parameterisations of the dark energy equation of state. Our results indicate that these Dark Scattering models have very mild effects on many observables related to large-scale structures formation and evolution, while providing a significant suppression of the amplitude of linear density perturbations and the abundance of massive clusters. Our simulations therefore confirm that these models offer a promising route to alleviate existing tensions between low-redshift measurements and those of the CMB.