Calculation of distances in cosmological models with small-scale inhomogeneities and their use in observational cosmology: a review

The Universe is not completely homogeneous. Even if it is sufficiently so on large scales, it is very inhomogeneous at small scales, and this has an effect on light propagation, so that the distance as a function of redshift, which in many cases is defined via light propagation, can differ from the...

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Bibliographic Details
Main Author: Phillip Helbig
Format: Article
Language:English
Published: Maynooth Academic Publishing 2020-01-01
Series:The Open Journal of Astrophysics
Subjects:
Online Access:https://astro.theoj.org/article/11632-calculation-of-distances-in-cosmological-models-with-small-scale-inhomogeneities-and-their-use-in-observational-cosmology-a-review
Description
Summary:The Universe is not completely homogeneous. Even if it is sufficiently so on large scales, it is very inhomogeneous at small scales, and this has an effect on light propagation, so that the distance as a function of redshift, which in many cases is defined via light propagation, can differ from the homogeneous case. Simple models can take this into account. I review the history of this idea, its generalization to a wide variety of cosmological models, analytic solutions of simple models, comparison of such solutions with exact solutions and numerical simulations, applications, simpler analytic approximations to the distance equations, and (for all of these aspects) the related concept of a “Swiss-cheese” universe.
ISSN:2565-6120