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Title: Dark energy anisotropic stress and large scale structure formation

Abstract

We investigate the consequences of an imperfect dark energy fluid on the large scale structure. A phenomenological three parameter fluid description is used to study the effect of dark energy on the cosmic microwave background radiation (CMBR) and matter power spectrum. In addition to the equation of state and the sound speed, we allow a nonzero viscosity parameter for the fluid. Then anisotropic stress perturbations are generated in dark energy. In general, we find that this possibility is not excluded by the present day cosmological observations. In the simplest case when all of the three parameters are constant, we find that the observable effects of the anisotropic stress can be closely mimicked by varying the sound speed of perfect dark energy. However, now also negative values for the sound speed, as expected for adiabatic fluid model, are tolerable and in fact could explain the observed low quadrupole in the CMBR spectrum. We investigate also structure formation of imperfect fluid dark energy characterized by an evolving equation of state. In particular, we study models unifying dark energy with dark matter, such as the Chaplygin gas or the Cardassian expansion, with a shear perturbation included. This can stabilize the growth of inhomogeneitiesmore » in these models, thus somewhat improving their compatibility with large scale structure observations.« less

Authors:
 [1];  [2]
  1. Helsinki Institute of Physics, FIN-00014 Helsinki (Finland)
  2. Institute of Theoretical Astrophysics, University of Oslo, Box 1029, 0315 Oslo (Norway)
Publication Date:
OSTI Identifier:
20782873
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.73.083502; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANISOTROPY; COSMIC RADIATION; COSMOLOGY; DISTURBANCES; ENERGY SPECTRA; EQUATIONS OF STATE; FLUID MECHANICS; FLUIDS; NONLUMINOUS MATTER; QUADRUPOLES; RADIOWAVE RADIATION; RELICT RADIATION; SHEAR; SOUND WAVES; STRESSES; VISCOSITY

Citation Formats

Koivisto, Tomi, and Mota, David F. Dark energy anisotropic stress and large scale structure formation. United States: N. p., 2006. Web. doi:10.1103/PHYSREVD.73.083502.
Koivisto, Tomi, & Mota, David F. Dark energy anisotropic stress and large scale structure formation. United States. doi:10.1103/PHYSREVD.73.083502.
Koivisto, Tomi, and Mota, David F. Sat . "Dark energy anisotropic stress and large scale structure formation". United States. doi:10.1103/PHYSREVD.73.083502.
@article{osti_20782873,
title = {Dark energy anisotropic stress and large scale structure formation},
author = {Koivisto, Tomi and Mota, David F.},
abstractNote = {We investigate the consequences of an imperfect dark energy fluid on the large scale structure. A phenomenological three parameter fluid description is used to study the effect of dark energy on the cosmic microwave background radiation (CMBR) and matter power spectrum. In addition to the equation of state and the sound speed, we allow a nonzero viscosity parameter for the fluid. Then anisotropic stress perturbations are generated in dark energy. In general, we find that this possibility is not excluded by the present day cosmological observations. In the simplest case when all of the three parameters are constant, we find that the observable effects of the anisotropic stress can be closely mimicked by varying the sound speed of perfect dark energy. However, now also negative values for the sound speed, as expected for adiabatic fluid model, are tolerable and in fact could explain the observed low quadrupole in the CMBR spectrum. We investigate also structure formation of imperfect fluid dark energy characterized by an evolving equation of state. In particular, we study models unifying dark energy with dark matter, such as the Chaplygin gas or the Cardassian expansion, with a shear perturbation included. This can stabilize the growth of inhomogeneities in these models, thus somewhat improving their compatibility with large scale structure observations.},
doi = {10.1103/PHYSREVD.73.083502},
journal = {Physical Review. D, Particles Fields},
number = 8,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}