Theoretical Priors On Modified Growth Parametrisations

TL;DR

This paper explores theoretical predictions for modified growth functions in various gravity and dark energy models, aiding future observations in distinguishing the underlying physics of cosmic acceleration.

Contribution

It provides a detailed analysis of the theoretical priors on growth parameterisations in Brans-Dicke, clustering dark energy, and interacting dark energy models.

Findings

Distinct paths in parameter space for each model

Theoretical priors help interpret upcoming structure formation data

Enhanced understanding of gravity and dark energy effects on structure growth

Abstract

Next generation surveys will observe the large-scale structure of the Universe with unprecedented accuracy. This will enable us to test the relationships between matter over-densities, the curvature perturbation and the Newtonian potential. Any large-distance modification of gravity or exotic nature of dark energy modifies these relationships as compared to those predicted in the standard smooth dark energy model based on General Relativity. In linear theory of structure growth such modifications are often parameterised by virtue of two functions of space and time that enter the relation of the curvature perturbation to, first, the matter over-density, and second, the Newtonian potential. We investigate the predictions for these functions in Brans-Dicke theory, clustering dark energy models and interacting dark energy models. We find that each theory has a distinct path in the parameter space of modified growth. Understanding these theoretical priors on the parameterisations of modified growth is essential to reveal the nature of cosmic acceleration with the help of upcoming observations of structure formations.