Motivated by the large-scale asymmetry observed in the cosmic microwave background sky , we consider a specific class of anisotropic cosmological models – Bianchi type VII _ { h } – and compare them to the WMAP first-year data on large angular scales .
Remarkably , we find evidence of a correlation which is ruled out as a chance alignment at the 3 \sigma level .
The best fit Bianchi model corresponds to x = 0.55 , \Omega _ { 0 } = 0.5 , a rotation axis in the direction ( l,b ) = ( 222 \arcdeg, - 62 \arcdeg ) , shear \left ( \frac { \sigma } { H } \right ) _ { 0 } = 2.4 \times 10 ^ { -10 } and a right–handed vorticity \left ( \frac { \omega } { H } \right ) _ { 0 } = 6.1 \times 10 ^ { -10 } .
Correcting for this component greatly reduces the significance of the large-scale power asymmetry , resolves several anomalies detected on large angular scales ( ie .
the low quadrupole amplitude and quadrupole/octopole planarity and alignment ) , and can account for a non–Gaussian “ cold spot ” on the sky .
Despite the apparent inconsistency with the best-fit parameters required in inflationary models to account for the acoustic peaks , we consider the results sufficiently provocative to merit further consideration .