Dmitry I. Novikov

The Gauss-Legendre Sky Pixelization for the CMB polarization (GLESP-pol). Errors due to pixelization of the CMB sky

We present the development of the method for numerical analysis of polarization in the Gauss–Legendre sky pixelization (GLESP) scheme for CMB maps. This incorporation of the polarization transforms in the pixelization scheme GLESP completes the creation of our new method for numerical analysis of CMB maps. A comparison of GLESP and HEALPix calculations is done.

Understanding the WMAP Cold Spot mystery

The Cold Spot (CS) at galactic coordinates (b = −57°, l = 209°) was discovered in the Wilkinson Microwave Anisotropy Probe (WMAP)data as a cosmic background anomaly. In order to assess the cosmological significance of the Spot, we examine its properties using the cluster analysis of the local extrema in the cosmic microwave background (CMB) signal. We also check the hypothesis that the CMB signal has a non-Gaussian tail, localized in the low-multipole components. We constructed a linear filter, dividing the signal into two parts: non-Gaussian and Gaussian. Using the filter scale as a variable, we can maximize the skewness and kurtosis of the smoothed signal and minimize these statistics. We discovered that the shape of the CS is formed primarily by the components of the CMB signal represented by the multipoles between 10 ≤ ℓ ≤ 20, with a corresponding angular scale of about 5°–10°. This signal leads to the modulation of the CMB on the whole sky, clearly seen at |b| > 30° in both the ILC andWCM maps, rather than in a single localized feature. After subtraction of this modulation, the remaining part of the CMB signal appears to be consistent with statistical homogeneity and Gaussianity. We therefore infer that the mystery of the WMAP Cold Spot reflects directly the peculiarities of low multipoles of the CMB signal, rather than a single local (isolated) defect or the manifestations of a globally anisotropic cosmology.

Peculiarities of anisotropy and polarization as an indicator of noises in the CMB maps

We discuss some new problems of the modern cosmology which arose after the BOOMERANG and MAXIMA-1 successful missions. Statistics of high peaks of the CMB anisotropy is analyzed and we discuss possible inner structure of such peaks in the observational data of future MAP and PLANCK missions. We have investigated geometrical and statistical properties of the CMB polarization around such high isolated peaks of anisotropy in the presence of a polarized pixel noise and point sources. The structure of polarization fields in the vicinity of singular points with zero polarization is very sensitive to the level of pixel noises and point sources in the CMB maps.We discuss some new problems of the modern cosmology which arose after the BOOMERANG and MAXIMA-1 successful missions. Statistics of high peaks of the CMB anisotropy is analyzed and we discuss possible inner structure of such peaks in the observational data of future MAP and PLANCK missions. We have investigated geometrical and statistical properties of the CMB polarization around such high isolated peaks of anisotropy in the presence of a polarized pixel noise and point sources. The structure of polarization fields in the vicinity of singular points with zero polarization is very sensitive to the level of pixel noises and point sources in the CMB maps.