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Title: Cosmological back-reaction in modified gravity and its implications for dark energy

We study the effective stress-energy tensor induced by cosmological inhomogeneity in f(R)=R+c R{sup 2} and equivalent scalar-tensor theories, motivated both by models of early universe inflation and by phenomenological alternative cosmologies to the standard Λ-CDM. We use Green and Wald's framework for averaging over classical fluctuations of short-wavelength λ. By ensuring that the leading non-linear terms from the fluctuations of the Einstein terms and the corrections both contribute in the formal limit as λ→0, we derive a diffeomorphism invariant effective stress-energy tensor whose trace is non-vanishing and of the right sign to potentially account for the current acceleration of the universe. However a more phenomenologically acceptable dark energy model would be required if this effect were to fully account for the current acceleration.
Authors:
;  [1]
  1. School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom)
Publication Date:
OSTI Identifier:
22375889
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 09; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CORRECTIONS; COSMOLOGICAL INFLATION; COSMOLOGY; FLUCTUATIONS; GRAVITATION; NONLINEAR PROBLEMS; NONLUMINOUS MATTER; POTENTIALS; SCALARS; TENSORS; UNIVERSE; WAVELENGTHS