K-mouflage Cosmology: Formation of Large-Scale Structures

Abstract

We study structure formation in K-mouflage cosmology whose main feature is the absence of screening effect on quasilinear scales. We show that the growth of structure at the linear level is affected by both 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 nonlinearities 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 nonlinear scales where a halo model is utilized. We find that the discrepancy peaks around $1h{\mathrm{Mpc}}^{-1}$ 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.

24 pages

References in corpus (3)

• Dynamics of dark energy
• A Map of the Integrated Sachs-Wolfe Signal from Luminous Red Galaxies
• Structure Formation in Modified Gravity Scenarios

Cited by in corpus (10)

• Beyond the Cosmological Standard Model
• Nonlinear structure formation in Nonlocal Gravity
• Speeding up $N$-body simulations of modified gravity: Chameleon screening models
• A Fast Route to Non-Linear Clustering Statistics in Modified Gravity Theories
• A parametrisation of modified gravity on nonlinear cosmological scales
• Equivalence of cosmological observables in conformally related scalar tensor theories
• Small-scale Nonlinear Dynamics of K-mouflage Theories
• Cosmological tests of modified gravity: constraints on $F(R)$ theories from the galaxy clustering ratio
• The Quantum Field Theory of K-mouflage
• Linear perturbations in K-mouflage cosmologies with massive neutrinos