Simultaneous effect of Modified Gravity and Primordial Non-Gaussianity in Large Scale Structure Observations

TL;DR

This paper investigates how primordial non-Gaussianity and modified gravity jointly influence large-scale structure, revealing their scale-dependent effects on bias, growth rate, and galaxy power spectrum, and proposing new observational parameters.

Contribution

It introduces a comprehensive analysis of combined effects of non-Gaussianity and $f(R)$ gravity on large-scale structure, including new observational parameters for cosmological constraints.

Findings

Non-Gaussianity affects large scales, modified gravity impacts small scales.

Redshift space distortion distinguishes positive and negative $f_{NL}$ in standard models.

Galaxy power spectrum is enhanced by non-Gaussianity and modified gravity.

Abstract

In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in $f(R)$ framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale dependent bias and growth rate functions. The deviation from $\Lambda$CDM in the case of primordial non-Gaussian models is in large scales, while the growth rate deviates from $\Lambda$CDM in small scales for modified gravity theories. We show that the redshift space distortion can be used to distinguish positive and negative $f_{NL}$ in standard background, while in $f(R)$ theories they are not easily distinguishable. The galaxy power spectrum is generally enhanced in presence of non-Gaussianity and modified gravity. We also obtain the scale dependence of this enhancement. Finally we define galaxy growth rate and galaxy growth rate bias as new observational parameters to constrain cosmology.