Large Scale Structures in Kinetic Gravity Braiding Model That Can Be Unbraided

TL;DR

This paper investigates the cosmological implications of the kinetic gravity braiding model, highlighting its similarities to LCDM for certain parameters and exploring its potential to be distinguished through large-scale structure observations.

Contribution

It provides a detailed analysis of the background and perturbation evolution in the kinetic braiding model, and assesses its observational signatures compared to LCDM.

Findings

Background expansion matches LCDM for n=∞

Linear perturbation evolution reduces to LCDM for n=∞

Potential to distinguish models via large-scale structure data

Abstract

We study cosmological consequences of a kinetic gravity braiding model, which is proposed as an alternative to the dark energy model. The kinetic braiding model we study is characterized by a parameter n, which corresponds to the original galileon cosmological model for n=1. We find that the background expansion of the universe of the kinetic braiding model is the same as the Dvali-Turner's model, which reduces to that of the standard cold dark matter model with a cosmological constant (LCDM model) for n equal to infinity. We also find that the evolution of the linear cosmological perturbation in the kinetic braiding model reduces to that of the LCDM model for n=\infty. Then, we focus our study on the growth history of the linear density perturbation as well as the spherical collapse in the nonlinear regime of the density perturbations, which might be important in order to distinguish between the kinetic braiding model and the LCDM model when n is finite. The theoretical prediction for the large scale structure is confronted with the multipole power spectrum of the luminous red galaxy sample of the Sloan Digital Sky survey. We also discuss future prospects of constraining the kinetic braiding model using a future redshift survey like the WFMOS/SuMIRe PFS survey as well as the cluster redshift distribution in the South Pole Telescope survey.