Modelling the emergence of cosmic anisotropy from non-linear structures

Abstract

Astronomical observations suggest that the Universe may be anisotropic on the largest scales. In order to model this situation, we develop a new approach to cosmology that allows for large-scale anisotropy to emerge from the growth of non-linear structure. This is achieved by decomposing all relevant fields with respect to a preferred space-like direction, and then averaging the resulting scalar quantities over spatial domains. Our approach allows us to derive a set of large-scale effective field equations that govern the dynamics of any emergent large-scale anisotropy, and which (up to back-reaction terms) take the form of the field equations of the locally rotationally symmetric Bianchi cosmologies. We apply our approach to the dust-filled Farnsworth solutions, which are an interesting set of exact cosmological models that allow for both anisotropic expansion and large-scale bulk flow.

33 pages, 8 figures. Typo corrected in Eq. (21)

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Cited by in corpus (4)

• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Covariant cosmography: the observer-dependence of the Hubble parameter
• A novel approach to cosmological non-linearities as an effective fluid
• Hubble Diagrams in Statistically Homogeneous, Anisotropic Universes