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Journal Articles Physical Review D Year : 2014

K-mouflage cosmology: formation of large-scale structures

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Abstract

We study structure formation in K-mouflage cosmology whose main feature is the absence of screening effect on quasi-linear scales. We show that the growth of structure at the linear level is both affected by a new time dependent Newton constant and a friction term which depend on the background evolution. These combine with the modified background evolution to change the growth rate by up to ten percent since $z\sim 2$. At the one loop level, we find that the non-linearities of the K-mouflage models are mostly due to the matter dynamics and that the scalar perturbations can be treated at tree level. We also study the spherical collapse in K-mouflage models and show that the critical density contrast deviates from its $\Lambda$-CDM value and that, as a result, the halo mass function is modified for large masses by an order one factor. Finally we consider the deviation of the matter spectrum from $\Lambda$-CDM on non-linear scales where a halo model is utilised. We find that the discrepancy peaks around $1\ h{\rm Mpc}^{-1}$ with a relative difference which can reach fifty percent. Importantly, these features are still true at larger redshifts, contrary to models of the chameleon-$f(R)$ and Galileon types.
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Dates and versions

cea-00982373 , version 1 (24-02-2021)

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Philippe Brax, Patrick Valageas. K-mouflage cosmology: formation of large-scale structures. Physical Review D, 2014, 90, pp.023508. ⟨10.1103/PhysRevD.90.023508⟩. ⟨cea-00982373⟩
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