Late time anisotropy as an imprint of cosmological backreaction
  Backreaction effects of the large scale structure on the background dynamics
have been claimed to lead to a renormalization of the background dynamics that
may account for the late time acceleration of the cosmic expansion. This
article emphasizes that generically the averaged flow is locally anisotropic, a
property that can be related to observation. Focusing on perturbation theory,
the spatially averaged shear, that characterizes the anisotropy of the flow, is
computed. It is shown that this shear arising from backreaction differs from a
homogeneous shear: its time evolution is different and its amplitude is
completely determined by the cosmological parameters and the matter power
spectrum. It ranges within (2-37)% at a redshift of order 0.5 so that the
isotropy of the Hubble flow may allow to constrain the backreaction approach to
dark energy.
