Bulk Viscosity Effects on the Early Universe Stability

  title={Bulk Viscosity Effects on the Early Universe Stability},
  author={Nakia Carlevaro and Giovanni Montani},
  journal={Modern Physics Letters A},
We present a discussion of the effects induced by the bulk viscosity on the very early Universe stability. The matter filling the cosmological (isotropic and homogeneous) background is described by a viscous fluid having an ultrarelativistic equation of state and whose viscosity coefficient is related to the energy density via a power-law of the form ζ = ζ0 ρν. The analytic expression of the density contrast (obtained for ν = 1/2) shows that, for small values of the constant ζ0, its behavior is… 
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