N-Body Simulations of DGP and Degravitation Theories

TL;DR

This paper uses N-body simulations to study how theories with extra dimensions and massive gravitons affect cosmic structure formation, providing new fitting formulas for power spectra and insights into their observational viability.

Contribution

It introduces a modified fitting formula for power spectra in higher-dimensional gravity models, improving upon previous methods and applicable to a broad class of theories.

Findings

Enhanced gravitational clustering on mildly nonlinear scales.

Modified fitting formula accurately matches simulation results.

Results are consistent with galaxy survey data for certain graviton wavelengths.

Abstract

We perform N-body simulations of theories with infinite-volume extra dimensions, such as the Dvali-Gabadadze-Porrati (DGP) model and its higher-dimensional generalizations, where 4D gravity is mediated by massive gravitons. The longitudinal mode of these gravitons mediates an extra scalar force, which we model as a density-dependent modification to the Poisson equation. This enhances gravitational clustering, particularly on scales that have undergone mild nonlinear processing. While the standard non-linear fitting algorithm of Smith et al. overestimates this power enhancement on non-linear scales, we present a modified fitting formula that offers a remarkably good fit to our power spectra. Due to the uncertainty in galaxy bias, our results are consistent with precision power spectrum determinations from galaxy redshift surveys, even for graviton Compton wavelengths as small as 300 Mpc. Our model is sufficiently general that we expect it to capture the phenomenology of a wide class of related higher-dimensional gravity scenarios.