On cosmic acceleration without dark energy
Abstract
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 negativepressure 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 nogo 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 generalrelativistic cosmological perturbations, applying, where possible, the renormalization group to regularize the dynamics. We show that an instability occurs in the perturbative expansion involving subHubble modes, which indicates that acceleration in our Hubble patch may originate from the backreaction of cosmological perturbations on observable scales.
 Authors:
 Publication Date:
 Research Org.:
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 15017088
 Report Number(s):
 FERMILABPUB05242A
arXiv eprint number astroph/0506534; TRN: US200621%%322
 DOE Contract Number:
 AC0276CH03000
 Resource Type:
 Journal Article
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCELERATION; INSTABILITY; MODIFICATIONS; RENORMALIZATION; UNIVERSE; ASTROPHYSICS; Astrophysics
Citation Formats
Kolb, E.W., /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI, Matarrese, S., /Padua U. /INFN, Padua, Riotto, A., and /INFN, Padua. On cosmic acceleration without dark energy. United States: N. p., 2005.
Web.
Kolb, E.W., /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI, Matarrese, S., /Padua U. /INFN, Padua, Riotto, A., & /INFN, Padua. On cosmic acceleration without dark energy. United States.
Kolb, E.W., /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI, Matarrese, S., /Padua U. /INFN, Padua, Riotto, A., and /INFN, Padua. 2005.
"On cosmic acceleration without dark energy". United States.
doi:. https://www.osti.gov/servlets/purl/15017088.
@article{osti_15017088,
title = {On cosmic acceleration without dark energy},
author = {Kolb, E.W. and /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI and Matarrese, S. and /Padua U. /INFN, Padua and Riotto, A. and /INFN, Padua},
abstractNote = {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 negativepressure 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 nogo 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 generalrelativistic cosmological perturbations, applying, where possible, the renormalization group to regularize the dynamics. We show that an instability occurs in the perturbative expansion involving subHubble modes, which indicates that acceleration in our Hubble patch may originate from the backreaction of cosmological perturbations on observable scales.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2005,
month = 6
}

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