Structure Formation by Fifth Force: Power Spectrum from N-Body Simulations

Abstract

We lay out the framework to numerically study nonlinear structure formation in the context of scalar-field-coupled cold dark matter models (phiCDM models) where the scalar field phi serves as dynamical dark energy. Adopting parameters for the scalar field which yield a realistic CMB spectrum, we generate the initial conditions for our Nbody simulations, which follow the spatial distributions of dark matter and the scalar field, by solving their equations of motion using the multilevel adaptive grid technique. We show that the spatial configuration of the scalar field tracks both the voids and clusters of dark matter. The phiCDM model differs from standard LCDM at small scales with observable modifications of, e.g., the mass function of halos as well as the matter power spectrum. Nevertheless, the predictions of both models for the Hubble expansion and the CMB spectrum are virtually indistinguishable. Hence, galaxy cluster counts and weak lensing observations, which probe structure formation at small scales, are needed to falsify this class of models.

5 pages, 3 figures, Discussion improved, conclusions unchanged. Accepted for publication on ApJ Letters

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• Structure Formation in the Symmetron Model
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• Systematic simulations of modified gravity: symmetron and dilaton models
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• Constraining $f(R)$ gravity by the Large Scale Structure
• Systematic simulations of modified gravity: chameleon models
• N-body Simulations for Extended Quintessence Models
• A comparison of structure formation in minimally and non-minimally coupled quintessence models
• Structure Formation by the Fifth Force III: Segregation of Baryons and Dark Matter
• Speeding up $N$-body simulations of modified gravity: Chameleon screening models
• Hydrodynamical simulations of galaxy clusters in dark energy cosmologies: II. c-M relation
• Gravity theories, Transverse Doppler and Gravitational Redshifts in Galaxy Clusters
• On the Effects of Coupled Scalar Fields on Structure Formation
• Hydrodynamical simulations of galaxy clusters in dark energy cosmologies: I. general properties
• DM haloes in the fifth-force cosmology
• The signature of the scattering between dark sectors in large scale cosmic microwave background anisotropies
• Varying alpha from N-body Simulations
• Testing model independent modified gravity with future large scale surveys
• Do Bound Structures Brake Cosmic Acceleration?
• Stellar Streams in Chameleon Gravity
• (Non-) geodesic motion in chameleon Brans Dicke model
• A short review on Quintom dark energy theory
• Dark Energy Simulations
• The galaxy cluster concentration-mass relation in dark energy cosmologies