Cosmological Probes of Structure Growth and Tests of Gravity

Abstract

The current standard cosmological model is constructed within the framework of general relativity with a cosmological constant Λ, which is often associated with dark energy, and phenomenologically explains the accelerated cosmic expansion. Understanding the nature of dark energy is one of the most appealing questions in achieving a self-consistent physical model at cosmological scales. Modification of general relativity could potentially provide a more natural and physical solution to the accelerated expansion. The growth of the cosmic structure is sensitive in constraining gravity models. In this paper, we aim to provide a concise introductory review of modified gravity models from an observational point of view. We will discuss various mainstream cosmological observables, and their potential advantages and limitations as probes of gravity models.

Sweeping Horndeski canvas: new growth-rate parameterization for modified-gravity theories

“…These measurements then translate into constraints on models of dark matter and dark energy or modified gravity (see, e.g. [1] for a recent, general review).…”

“…For the standard, smooth dark-energy with an equation of state w, on sub-horizon-scales and in the absence of massive neutrinos, D and f are scale-independent. 1 The growth rate can be formally obtained by solving the second-order JCAP09(2023)028 differential equation which, in standard gravity and on sub-horizon scales, reads D + 2H Ḋ = 4πGρ M D. Here ρ M is the background matter density, G is the Newton constant, and dots are derivatives with respect to time.…”