The CIDER simulations: Nonlinear structure formation in the Constrained Interacting Dark Energy Scenario

TL;DR

This paper introduces cosmological simulations for the CIDER model, a constrained interacting dark energy scenario that suppresses late-time structure formation, potentially resolving the sigma_8 tension without affecting background observations.

Contribution

First simulation suite for CIDER models, analyzing their nonlinear structure formation effects and potential to distinguish from standard cosmology.

Findings

Scalar potential close to exponential during matter domination

Nonlinear structure evolution leaves unique signatures on matter and halo statistics

Potential to break degeneracies with standard cosmological parameters

Abstract

We present for the first time a suite of cosmological simulations for a particular class of interacting Dark Energy cosmologies characterised by a background expansion history constrained to be indistinguishable from $\Lambda $CDM. Such Constrained Interacting Dark Energy scenario -- or CIDER -- has been recently proposed by Barros et al. 2019 and has the appealing feature of suppressing structure formation at late times, thereby possibly alleviating the persisting $\sigma _{8}$ tension while leaving background observables unaffected. A crucial step to assess the viability of such scenarios is then represented by quantifying their impact on structure formation at non-linear scales, which is what we start investigating with the simulations discussed in the present work. We show that -- for reasonable parameter choices -- the reconstructed scalar potential is close to an exponential for most of the matter dominated epoch, and that the nonlinear evolution of structures in these models imprints specific footprints on matter and halo statistics that may allow to break degeneracies with standard cosmological parameters.