Large scale structures in the kinetic gravity braiding model that can be unbraided

Abstract

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 (ΛCDM 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 ΛCDM model for n = ∞. 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 ΛCDM 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.

Effective gravitational couplings for cosmological perturbations in the most general scalar–tensor theories with second-order field equations

“…This leads to the modified growth rate of matter density perturbations δ m as well as the modified evolution of the effective gravitational potential Φ eff associated with the deviation of light rays. Similar analysis has been carried out in specific scalar-tensor theories [6,[27][28][29][30][31], f (R) theories [31,32], kinetic gravity braidings with the term L 3 [33][34][35][36][37], and covariant Galileon [38]. Our analysis in this paper covers those theories as specific cases.…”

“…[37] in which the authors studied the evolution of perturbations for the functions K = −X and G 3 ∝ X n (which corresponds to the Dvali and Turner model [23]). One can also extend the analysis to the case where…”

Cosmological Tests of Modified Gravity with Future Observations of Growth Rate of Matter Density Perturbations

“…Kinetic gravity braiding model [9] is proposed as an alternative to the dark energy model. One can say that kinetic gravity braiding model is specific aspects of Horndeski's theory [6].…”

“…Kinetic gravity braiding model [9] correspond to a case that the functions in the Horndeski's theory are given as follows:…”

“…Thus, it is important to study the growth history of perturbations to distinguish modified gravity from models based on the cosmological constant or dark energy. We adopt Kinetic Gravity Braiding model [9] and Galileon model [10,11] as modified gravity models. Kinetic Gravity Braiding model and Galileon model are specific aspects of Horndeski's theory.…”