Evaluating backreaction with the ellipsoidal collapse model

@article{Montanari2017EvaluatingBW,
  title={Evaluating backreaction with the ellipsoidal collapse model},
  author={Francesco Montanari and Syksy Rasanen},
  journal={arXiv: Cosmology and Nongalactic Astrophysics},
  year={2017}
}
We evaluate the effect of structure formation on the average expansion rate with a statistical treatment where density peaks and troughs are modelled as homogeneous ellipsoids. This extends earlier work that used spherical regions. We find that the shear and the presence of filamentary and planar structures have only a small impact on the results. The expansion rate times the age of the universe $Ht$ increases from 2/3 to 0.83 at late times, in order of magnitude agreement with observations… 
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