Exact inhomogeneous models and the drift of light rays induced by nonsymmetric flow of the cosmic medium

Abstract

After introducing the Szekeres and Lema\^ıtre--Tolman cosmological models, the real-time cosmology program is briefly mentioned. Then, a few widespread misconceptions about the cosmological models are pointed out and corrected. Investigation of null geodesic equations in the Szekeres models shows that observers in favourable positions would see galaxies drift across the sky at a rate of up to $10^{-6}$ arc seconds per year. Such a drift would be possible to measure using devices that are under construction; the required time of monitoring would be $\approx 10$ years. This effect is zero in the FLRW models, so it provides a measure of inhomogeneity of the Universe. In the Szekeres models, the condition for zero drift is zero shear. But in the shearfree normal models, the condition for zero drift is that, in the comoving coordinates, the time dependence of the metric completely factors out.

8 pages, 5 figures, based on the talk delivered at the Marcel Grossman Meeting 13 in Stockholm, 2012. Sections and references permuted, one figure added, title changed, style corrections in text; actual content not changed. Changes done in response to referee's opinion

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Cited by in corpus (8)

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• Calculating Observables in Inhomogeneous Cosmologies I: General Framework
• Physical geometry of the quasispherical Szekeres models
• Redshift drift in a universe with structure II: Light rays propagated through a Newtonian N-body simulation
• Algebraic symmetries of the observables on the sky: Variable emitters and observers