On dark degeneracy and interacting models

Feb 10, 2014
5 pages
Published in:
  • JCAP 06 (2014) 010
  • Published: 2014
e-Print:

Citations per year

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Abstract: (arXiv)
Cosmological background observations cannot fix the dark energy equation of state, which is related to a degeneracy in the definition of the dark sector components. Here we show that this degeneracy can be broken at perturbation level by imposing two observational properties on dark matter. First, dark matter is defined as the clustering component we observe in large scale structures. This definition is meaningful only if dark energy is unperturbed, which is achieved if we additionally assume, as a second condition, that dark matter is cold, i.e. non-relativistic. As a consequence, dark energy models with equation-of-state parameter 1ω<0-1 \le\omega< 0 are reduced to two observationally distinguishable classes with ω=1\omega = -1, equally competitive when tested against observations. The first comprises the Λ\LambdaCDM model with constant dark energy density. The second consists of interacting models with an energy flux from dark energy to dark matter.
Note:
  • Version accepted for publication in JCAP
  • cosmological perturbation theory
  • dark energy theory
  • interaction: model
  • dark energy: equation of state
  • dark energy: density
  • energy: flux
  • dark matter: parametrization
  • cosmological model: parameter space
  • nonrelativistic
  • perturbation