Observational Cosmology in Macroscopic Gravity

TL;DR

This paper develops cosmological models within Macroscopic Gravity, deriving new exact solutions and analyzing perturbations, aiming to provide an alternative framework for interpreting cosmological data beyond the standard LCDM model.

Contribution

It introduces new exact FLRW solutions in Macroscopic Gravity and examines the impact of anisotropies and perturbations on cosmological measurements.

Findings

Inhomogeneous perturbations are highly restricted.

Anisotropies in the correlation tensor can significantly affect distance measurements.

First step towards using MG for real cosmological data analysis.

Abstract

We discuss the construction of cosmological models within the framework of Macroscopic Gravity (MG), which is a theory that models the effects of averaging the geometry of space-time on large scales. We find new exact spatially homogeneous and isotropic FLRW solutions to the MG field equations, and investigate large-scale perturbations around them. We find that any inhomogeneous perturbations to the averaged geometry are severely restricted, but that possible anisotropies in the correlation tensor can have dramatic consequences for the measurement of distances. These calculations are a first step within the MG approach toward developing averaged cosmological models to a point where they can be used to interpret real cosmological data, and hence to provide a working alternative to the "concordance" LCDM model.