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Observable Deviations from Homogeneity in an Inhomogeneous Universe
The Astrophysical Journal
  • John T. Giblin, Kenyon College
  • James B. Mertens, Case Western Reserve University
  • Glenn D. Starkman, Case Western Reserve University
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How does inhomogeneity affect our interpretation of cosmological observations? It has long been wondered to what extent the observable properties of an inhomogeneous universe differ from those of a corresponding Friedmann-Lemaitre-Robertson-Walker (FLRW) model, and how the inhomogeneities affect that correspondence. Here, we use numerical relativity to study the behavior of light beams traversing an inhomogeneous universe, and construct the resulting Hubble diagrams. The universe that emerges exhibits an average FLRW behavior, but inhomogeneous structures contribute to deviations in observables across the observer's sky. We also investigate the relationship between angular diameter distance and the angular extent of a source, finding deviations that grow with source redshift. These departures from FLRW are important path-dependent effects, with implications for using real observables in an inhomogeneous universe such as our own.
Citation Information
John T. Giblin, James B. Mertens and Glenn D. Starkman. "Observable Deviations from Homogeneity in an Inhomogeneous Universe" The Astrophysical Journal Vol. 833 Iss. 2 (2016)
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