On cosmic acceleration without dark energy
We elaborate on the proposal that the observed acceleration of the Universe is the result of the backreaction of cosmological perturbations, rather than the effect of a negative-pressure dark energy fluid or a modification of general relativity. Through the effective Friedmann equations describing an inhomogeneous Universe after smoothing, we demonstrate that acceleration in our local Hubble patch is possible even if fluid elements do not individually undergo accelerated expansion. This invalidates the no-go theorem that there can be no acceleration in our local Hubble patch if the Universe only contains irrotational dust. We then study perturbatively the time behavior of general-relativistic cosmological perturbations, applying, where possible, the renormalization group to regularize the dynamics. We show that an instability occurs in the perturbative expansion involving sub-Hubble modes, which indicates that acceleration in our Hubble patch may originate from the backreaction of cosmological perturbations on observable scales.
- Publication Date:
- OSTI Identifier:
- Report Number(s):
arXiv eprint number astro-ph/0506534; TRN: US200621%%322
- DOE Contract Number:
- Resource Type:
- Journal Article
- Research Org:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL
- Sponsoring Org:
- Country of Publication:
- United States
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCELERATION; INSTABILITY; MODIFICATIONS; RENORMALIZATION; UNIVERSE; ASTROPHYSICS Astrophysics
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