151. Too few spots in the cosmic microwave background
- Author
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Christof Wetterich, Youness Ayaita, and Maik Weber
- Subjects
Physics ,Nuclear and High Energy Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Spots ,Gaussian ,Isotropy ,Cosmic microwave background ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Lambda ,Cosmology ,symbols.namesake ,Quadrupole ,symbols ,Microwave ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We investigate the abundance of large-scale hot and cold spots in the WMAP-5 temperature maps and find considerable discrepancies compared to Gaussian simulations based on the LCDM best-fit model. Too few spots are present in the reliably observed cosmic microwave background (CMB) region, i.e., outside the foreground-contaminated parts excluded by the KQ75 mask. Even simulated maps created from the original WMAP-5 estimated multipoles contain more spots than visible in the measured CMB maps. A strong suppression of the lowest multipoles would lead to better agreement. The lack of spots is reflected in a low mean temperature fluctuation on scales of several degrees (4 to 8), which is only shared by less than 1% (0.16%-0.62%) of Gaussian LCDM simulations. After removing the quadrupole, the probabilities change to 2.5%-8.0%. This shows the importance of the anomalously low quadrupole for the statistical significance of the missing spots. We also analyze a possible violation of Gaussianity or statistical isotropy (spots are distributed differently outside and inside the masked region)., Comment: 12 pages; changes in the abstract, extended discussion of the quadrupole and the significances, minor clarifications, one added figure (behavior of typical simulations), one added reference
- Published
- 2009
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