a Recent paper establishes under solid grounds anisotropy in the expansion accel

Question

a Recent paper establishes under solid grounds anisotropy in the expansion acceleration rate in the universe. My question is very simple:

can this anomaly be explained entirely in terms of a cosmological constant?

I suspect that by adjusting the ? scale factor to depend not only on time but also on a unit direction it seems that one could explain the above anisotropy without appealing to any exotic field (other than a cosmological constant) but then you only do not know why the asymmetry in the boundary condition (early universe) exists in the first place

Explanation / Answer

I highly doubt quintessence is the only possibility, as long as the framework of models you are talking about is completely general.

I believe you could always create such anisotropies by introducing spatial variations in the Hubble rate (http://arxiv.org/abs/0709.2044), f.e. by invoking the cosmic bubble hypothesis, which assumes that we live inside an underdense region. As soon as we are not located in ther centre of the bubble, anisotropy should arise.

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