Simulations of Galileon modified gravity: Clustering statistics in real and redshift space

TL;DR

This paper uses N-body simulations to analyze how galileon modified gravity affects large-scale structure formation and redshift space distortions, highlighting potential observational signatures that distinguish it from standard gravity.

Contribution

It demonstrates that existing b5 CDM-based models can fit modified gravity simulation results with b5 adjustments and explores redshift space distortions as a probe of gravity modifications.

Findings

Enhanced clustering on scales >10 Mpc/h due to stronger gravity

Increased damping of correlation function at scales <9 Mpc/h

Redshift space distortions reveal differences from standard gravity models

Abstract

We use N-body simulations to study the statistics of massive halos and redshift space distortions for theories with a standard \Lambda CDM expansion history and a galileon-type scalar field. The extra scalar field increases the gravitational force, leading to enhanced structure formation. We compare our measurements of the real space matter power spectrum and halo properties with fitting formula for estimating these quantities analytically. We find that a model for power spectrum, halo mass-function and halo bias, derived from \Lambda CDM simulations can fit the results from our simulations of modified gravity when \sigma_8 is appropriately adjusted. We also study the redshift space distortions in the two point correlation function measured from these simulations, finding a difference in the ratio of the redshift space to real space clustering amplitude relative to standard gravity on all scales. We find enhanced clustering on scales r>10 Mpc/h and increased damping of the correlation function for scales r<9 Mpc/h. The boost in the clustering on large scales due to the enhanced gravitational forces cannot be mimicked in a standard gravity model by simply changing \sigma_8. This result illustrates the usefulness of redshift space distortion measurements as a probe of modifications to General Relativity.