Testing for Non-Gaussianity in the Wilkinson Microwave Anisotropy Probe Data: Minkowski Functionals and the Length of the Skeleton

By H. Eriksen, D. Novikov, P. Lilje, A. Banday, K. G'orski. 2004

154 citations recorded by the source corpus.

The three Minkowski functionals and the recently defined length of the skeleton are estimated for the co-added first-year Wilkinson Microwave Anisotropy Probe (WMAP) data and compared with 5000 Monte Carlo simulations, based on Gaussian fluctuations with the a priori best-fit running-index power spectrum and WMAP-like beam and noise properties. Several power spectrum-dependent quantities, such as the number of stationary points, the total length of the skeleton, and a spectral parameter, γ, are also estimated. While the area and length Minkowski functionals and the length of the skeleton show no evidence for departures from the Gaussian hypothesis, the northern hemisphere genus has a χ2 that is large at the 95% level for all scales. For the particular smoothing scale of 3.°40 FWHM it is larger than that found in 99.5% of the simulations. In addition, the WMAP genus for negative thresholds in the northern hemisphere has an amplitude that is larger than in the simulations with a significance of more than 3 σ. On the smallest angular scales considered, the number of extrema in the WMAP data is high at the 3 σ level. However, this can probably be attributed to the effect of point sources. Finally, the spectral parameter γ is high at the 99% level in the northern Galactic hemisphere, while perfectly acceptable in the southern hemisphere. The results provide strong evidence for the presence of both non-Gaussian behavior and an unexpected power asymmetry between the northern and southern hemispheres in the WMAP data.

Subfields: Astronomy and Astrophysics, Environmental Engineering, Oceanography

View Paper: https://www.semanticscholar.org/paper/7f8ff632b720cded1453c13008735549e86da033

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In Astronomy and Astrophysics

1. E. Komatsu
2. A. Banday
3. K. G'orski
4. H. Eriksen
5. David N. Spergel
6. Mark Halpern
7. C. Bennett
8. J. Weiland

In Oceanography

1. A. Banday
2. H. Eriksen
3. K. G'orski
4. F. Hansen
5. João Magueijo
6. K. Land
7. P. Lilje
8. J. Hoftuft

Citations in the corpus

• INCREASING EVIDENCE FOR HEMISPHERICAL POWER ASYMMETRY IN THE FIVE-YEAR WMAP DATA (2009, methodology): “Some early notable examples include unexpected low-ℓ correlations (de Oliveira-Costa et al. 2004), a peculiar large cold spot in the southern Galactic hemisphere (Vielva et al. 2004), and a dipolar distribution of large-scale power (Eriksen et al. 2004a).”
• The Axis of Evil revisited (2006, methodology): “• In an anlaysis of the ILC map-making method, Eriksen et al. (2004) proposed a faster algorithm for the computation of the weights, that employs Lagrangian multipliers to linearize the problem.”
• The non‐Gaussian cold spot in Wilkinson Microwave Anisotropy Probe: significance, morphology and foreground contribution (2006, background): “However also the TCM map presents complex noise properties (Eriksen et al 2004c).”
• FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2008, unknown): “…et al. 2007; Park 2004; de Oliveira-Costa et al. 2004; Tegmark et al. 2003; Larson & Wandelt 2004; Eriksen et al. 2004; Eriksen et al. 2004; Eriksen et al. 2004, 2007a; Copi et al. 2004; Schwarz et al. 2004; Copi et al. 2006, 2007; Gordon et al. 2005; Bielewicz et al. 2005; Jaffe et al.…”
• POWER ASYMMETRY IN COSMIC MICROWAVE BACKGROUND FLUCTUATIONS FROM FULL SKY TO SUB-DEGREE SCALES: IS THE UNIVERSE ISOTROPIC? (2008, methodology): “…as well as other statistical anomalies were confirmed by several other authors using other methods (de Oliveira-Costa et al. 2004; Tegmark et al. 2003; Park 2004; Vielva et al. 2004b; Eriksen et al. 2004b; Land & Magueijo 2005a,b; Larson & Wandelt 2004; McEwen et al. 2005; Hansen et al. 2004b,c).”
• Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, unknown): “Mostly probing general NG in a frequentist fashion in two-dimensions on CMB maps (Eriksen et al. 2004; Komatsu et al. 2005; Modest et al. 2013; Natoli et al. 2010; Curto et al. 2008) or three-dimensions on LSS data (Park et al.”
• SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: ARE THERE COSMIC MICROWAVE BACKGROUND ANOMALIES? (2010, methodology): “The first claimed hemispherical power asymmetry appeared in Eriksen et al. (2004), based on the first-year WMAP data, where a statistic for power asymmetry was constructed, and its value on high-resolution WMAP data was compared to an ensemble of Monte Carlo simulations in a direct frequentist…”