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Non-Gaussianities in the local curvature of the 5-year WMAP data | | Øystein Rudjord
; Nicolaas E. Groeneboom
; Frode K. Hansen
; Paolo Cabella
; | | Date: |
9 Feb 2010 | | Abstract: | Using the 5 year WMAP data, we re-investigate claims of non-Gaussianities and
asymmetries detected in local curvature statistics of the 1 year WMAP data. In
Hansen et al 2004, it was found that the northern ecliptic hemisphere was
non-Gaussian at the ~1% level testing the densities of hill-, lake and saddle
points based on the second derivatives of the CMB temperature map. The 5 year
WMAP data has a much lower noise level and better control of systematics. Using
these, we find that the anomalies are still present at a consistent level. Also
the direction of maximum non-Gaussianity remains. Due to limited availability
of computer resources, Hansen et al. 2004 were unable to calculate the full
covariance matrix for the chi^2 test used. Here we apply the full covariance
matrix instead of the diagonal approximation and find that the
non-Gaussianities disappear and there is no preferred non-Gaussian direction.
The cause of the non-Gaussian detection in the case of a diagonal matrix
remains unclear. | | Source: | arXiv, 1002.1811 | | Services: | Forum | Review | PDF | Favorites | |
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