[astro-ph/0511666] Mapping large-scale anisotropy in the WMAP data

Authors:  A. Bernui, B. Mota, M.J. Reboucas, R. Tavakol
Abstract:  Analyses of recent cosmic microwave background (CMB) observations have provided increasing indications for the existence of large scale anisotropy in the universe. Given the far reaching consequences of such an anisotropy for our understanding of the universe, it is important to employ alternative indicators in order to determine whether the reported anisotropy is cosmological in origin, and if so extract further information that may be helpful for identifying its causes. Here we propose a new directional indicator based on separation histograms of pairs of pixels with similar temperatures in the CMB map, as a measure of large scale anisotropy. The main advantage of this indicator is that it can be used to generate a sky map of large-scale anisotropies in the CMB temperature map, thus allowing a possible additional window into their causes. Using this indicator, we find a statistically significant (at 95% CL) preferred direction in the CMB data and discuss how it compares with other such axes recently reported. We also show that our findings are robust with respect to both the details of the method used, and the choice of the WMAP CMB maps employed.
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Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

[astro-ph/0511666] Mapping large-scale anisotropy in the WMA

Post by Garth Antony Barber » November 28 2005

In particular we have found, with high statistical significance (> 95% CL), a small region in the celestial sphere with very high values of σ, which defines a direction very close to the one reported recently [6, 10].
The 'Axis of Evil' strikes again?
Finally, regarding the origin of such large-scale anisotropy, a number of suggestions have been put forward. A detailed discussion of these suggestions is beyond the scope of the present work. Briefly though, they can arise either from a subtle form of unremoved foreground contamination (in which case the σ–map might
indicate where in the sky this contamination is most intense), or from the universe being genuinely anisotropic on large scales. This latter possibility is particularly interesting, as it would have potentially important consequences for the standard inflationary picture, which predicts statistically isotropic CMB temperature fluctuation patterns.
Among the proposed explanations, it has been suggested that the preferred direction could be due to the universe possessing a non-trivial topology
Life is just a dohnut?

Tommy Anderberg
Posts: 47
Joined: November 24 2005
Affiliation: independent

Re: [astro-ph/0511666] Mapping large-scale anisotropy in the

Post by Tommy Anderberg » November 28 2005

Garth Antony Barber wrote:Life is just a dohnut?
Polyhedron. ;)

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