Galaxy clustering constraints on deviations from Newtonian gravity at cosmological scales II: Perturbative and numerical analyses of power spectrum and bispectrum

TL;DR

This study uses galaxy clustering data from SDSS to constrain deviations from Newtonian gravity at cosmological scales, employing perturbation theory and N-body simulations to analyze power spectrum and bispectrum, and deriving bounds on modified gravity parameters.

Contribution

It introduces a combined perturbative and numerical approach to test a Yukawa-like modified gravity model against galaxy clustering data, validating previous empirical models.

Findings

Perturbation theory reliably estimates the power spectrum and bispectrum in the modified gravity model.

Constraints on the amplitude and length scale of deviations are consistent with earlier work.

Bispectrum constraints are similar to power spectrum constraints under linear biasing, with nonlinear biasing bounds also derived.

Abstract

We explore observational constraints on possible deviations from Newtonian gravity by means of large-scale clustering of galaxies. We measure the power spectrum and the bispectrum of Sloan Digital Sky Survey galaxies and compare the result with predictions in an empirical model of modified gravity. Our model assumes an additional Yukawa-like term with two parameters that characterize the amplitude and the length scale of the modified gravity. The model predictions are calculated using two methods; the second-order perturbation theory and direct N-body simulations. These methods allow us to study non-linear evolution of large-scale structure. Using the simulation results, we find that perturbation theory provides reliable estimates for the power spectrum and the bispectrum in the modified Newtonian model. We also construct mock galaxy catalogues from the simulations, and derive constraints on the amplitude and the length scale of deviations from Newtonian gravity. The resulting constraints from power spectrum are consistent with those obtained in our earlier work, indicating the validity of the previous empirical modeling of gravitational nonlinearity in the modified Newtonian model. If linear biasing is adopted, the bispectrum of the SDSS galaxies yields constraints very similar to those from the power spectrum. If we allow for the nonlinear biasing instead, we find that the ratio of the quadratic to linear biasing coefficients, b_2/b_1, should satisfy -0.4 < b_2/b_1<0.3 in the modified Newtonian model.