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Asymmetries in the local curvature of the WMAP data
Astrophysics · Submitted 17 Feb 2004
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim However, strong non-Gaussian features emerge when considering the northern and southern galactic hemisphere separately, particularly on scales between 1 and 5 degrees.
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The abstract, sentence by sentence
We use the local curvature to investigate the possible existence of non-Gaussianity/asymmetry in the WMAP data. Considering the full sky we find results which are consistent with the Gaussian assumption. However, strong non-Gaussian features emerge when considering the northern and southern galactic hemisphere separately, particularly on scales between 1 and 5 degrees. Quite interestingly, the maximum non-Gaussianity is found for hemispheres centered near the ecliptic poles, which might suggest the presence of some systematic effect. The direction of the asymmetry seems consistent with the findings by Eriksen et al. 2004.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We use the local curvature to investigate the possible existence of non-Gaussianity/asymmetry in the WMAP data. | contribution 0.75 | 0.91 | 0.05 | hedged possibility 0.46 |
| s1 | Considering the full sky we find results which are consistent with the Gaussian assumption. | result 1.00 | 0.96 | 0.17 | asserted 0.74 |
| s2 | However, strong non-Gaussian features emerge when considering the northern and southern galactic hemisphere separately, particularly on scales between 1 and 5 degrees. | result 1.00 | 0.94 | 0.54 | asserted 1.00 |
| s3 | Quite interestingly, the maximum non-Gaussianity is found for hemispheres centered near the ecliptic poles, which might suggest the presence of some systematic effect. | interpretation 0.63 | 0.92 | 0.13 | speculative 0.53 |
| s4 | The direction of the asymmetry seems consistent with the findings by Eriksen et al. 2004. | result 0.53 | 0.54 | 0.10 | hedged possibility 0.96 |
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The paper
Original abstract
We use the local curvature to investigate the possible existence of non-Gaussianity/asymmetry in the WMAP data. Considering the full sky we find results which are consistent with the Gaussian assumption. However, strong non-Gaussian features emerge when considering the northern and southern galactic hemisphere separately, particularly on scales between 1 and 5 degrees. Quite interestingly, the maximum non-Gaussianity is found for hemispheres centered near the ecliptic poles, which might suggest the presence of some systematic effect. The direction of the asymmetry seems consistent with the findings by Eriksen et al. 2004.
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References
How the literature uses it
18 arXiv papers cite this in 19 sentences
Papers citing it · 16 sentences without a confident label
Cites it as background 3 papers
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Indeed many authors have studied this issue directly and indirectly using various approaches and claimed the existence of a number of anomalies in the data (see e.g. [ref] and [ref] for recent reviews).
Giant Rings in the CMB Sky · Introduction · 0.97
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Among others, these include: bi-polar power spectrum [ref] , phase correlations tests [ref] , higher order correlations in SH space (bi/tri-spectrum) e.g. [ref] , $n$-point real space statistics: [ref] , morphological estimators (like Minkowski functionals) [ref] , multipole vectors [ref] higher order correlation functions [ref] , phase space statistics [ref] , wavelet space statistics [ref] , higher criticism statistic [ref] , pair angular separation histograms [ref] and also various real-space based tests eg: [ref] In particular a dedicated tests of hemispherical power asymmetry have been reported by many authors and found anomalous at confidence levels ranging from $∼2σ$ to $∼2.6σ$ ($95% CL ∼99%$ CL)
Real space tests of the statistical isotropy and Gaussianity of the WMAP CMB data · Introduction · 0.85
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These features concern (see [ref] for a recent review): a “cold spot” in the southern galactic hemisphere [ref] ; an alignment between the quadrupole and octupole modes in the temperature anisotropies [ref] ; an asymmetry in the large scale power spectrum and in higher-order correlation functions between the northern and the southern ecliptic hemisphere [ref] .
An Estimator for statistical anisotropy from the CMB bispectrum · Introduction · 0.86
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