Understand
We study the role of scale dependence in the Buchert averaging method, using the flat Lemaitre-Tolman-Bondi model as a testing ground.
- Within this model, a single averaging scale gives too coarse predictions, but by replacing it with the distance of the objects R(z) for each redshift z, we find an O(1%) precision at z<2 in the averaged luminosity and angular diameter distances compared to their exact expressions.
- At low redshifts, we show the improvement for generic inhomogeneity profiles, and our numerical computations further verify it up to redshifts z~2.
- At higher redshifts, the method breaks down due to its inability to capture the time evolution of the inhomogeneities.
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