Non-Gaussian distribution and clustering of hot and cold pixels in the five-year WMAP sky

作者：Rossi Graziano^*; Sheth Ravi K; Park Changbom; Hernandez Monteagudo Carlos

来源：Monthly Notices of the Royal Astronomical Society, 2009, 399(1): 304-316.

DOI：10.1111/j.1365-2966.2009.15278.x

• methods: data analysis
• methods: statistical
• cosmic microwave background
• cosmology: observations
• early Universe
• Large-scale structure of Universe

We present measurements of the clustering of hot and cold patches in the microwave background sky as measured from the Wilkinson Microwave Anisotropy Probe 5-year data. These measurements are compared with theoretical predictions which assume that the cosmological C signal obeys Gaussian statistics. We find significant differences from the simplest Gaussian-based prediction. However, the measurements are sensitive to the fact that the noise is spatially inhomogeneous (e.g. because different parts of the sky were observed for different lengths of time). We show how to account for this spatial inhomogeneity when making predictions. Differences from the Gaussian-based expectation remain even after this more careful accounting of the noise. In particular, we note that hot and cold pixels cluster differently within the same temperature thresholds at few-degree scales. While these findings may indicate primordial non-Gaussianity, we discuss other plausible explanations for these discrepancies. In addition, we find some deviations from Gaussianity at sub-degree scales, especially in the W band, whose origin may be associated with extragalactic dust emission.

• 出版日期2009-10-11