On light propagation in Swiss-Cheese cosmologies

TL;DR

This paper investigates how cosmic inhomogeneities in Swiss-Cheese models influence light propagation, suggesting they can mimic accelerated expansion effects, but the overall impact is minimal when photon paths are randomized.

Contribution

It provides a numerical analysis of light propagation in Swiss-Cheese cosmologies using Lemaitre-Tolman solutions, highlighting the limited but notable effects of inhomogeneities.

Findings

Inhomogeneities can partially mimic cosmic acceleration.

Randomizing photon trajectories diminishes the inhomogeneity effects.

Effects of inhomogeneities are generally small.

Abstract

We study the effect of inhomogeneities on light propagation. The Sachs equations are solved numerically in the Swiss-Cheese models with inhomogeneities modelled by the Lemaitre-Tolman solutions. Our results imply that, within the models we study, inhomogeneities may partially mimic the accelerated expansion of the Universe provided the light propagates through regions with lower than the average density. The effect of inhomogeneities is small and full randomization of the photons' trajectories reduces it to an insignificant level.