Understanding the WMAP cold spot mystery

Pavel Nasselski; Per Rex Christensen; P. Coles; O. Verkhodanov; Igor Dmitrievich Novikov; Ja. Kim

doi:10.1134/S199034131002001X

Understanding the WMAP cold spot mystery

Pavel Nasselski, Per Rex Christensen, P. Coles, O. Verkhodanov, Igor Dmitrievich Novikov, Ja. Kim

23 Citations (Scopus)

Abstract

The Cold Spot (CS) at galactic coordinates (b = -57°, l = 209°) was discovered in the WilkinsonMicrowave 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 {phipe}b{phipe} > 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.

Original language	English
Journal	Astrophysical Bulletin
Volume	65
Issue number	2
Pages (from-to)	101-120
Number of pages	20
ISSN	1990-3413
DOIs	https://doi.org/10.1134/S199034131002001X
Publication status	Published - Apr 2010

Access to Document

10.1134/S199034131002001X

Cite this

@article{6e28eab0ee9411dfb6d2000ea68e967b,

title = "Understanding the WMAP cold spot mystery",

abstract = "The Cold Spot (CS) at galactic coordinates (b = -57°, l = 209°) was discovered in the WilkinsonMicrowave 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 {phipe}b{phipe} > 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.",

author = "Pavel Nasselski and Christensen, {Per Rex} and P. Coles and O. Verkhodanov and Novikov, {Igor Dmitrievich} and Ja. Kim",

year = "2010",

month = apr,

doi = "10.1134/S199034131002001X",

language = "English",

volume = "65",

pages = "101--120",

journal = "Astrophysical Bulletin",

issn = "1990-3413",

publisher = "M A I K Nauka - Interperiodica",

number = "2",

}

TY - JOUR

T1 - Understanding the WMAP cold spot mystery

AU - Nasselski, Pavel

AU - Christensen, Per Rex

AU - Coles, P.

AU - Verkhodanov, O.

AU - Novikov, Igor Dmitrievich

AU - Kim, Ja.

PY - 2010/4

Y1 - 2010/4

N2 - The Cold Spot (CS) at galactic coordinates (b = -57°, l = 209°) was discovered in the WilkinsonMicrowave 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 {phipe}b{phipe} > 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.

AB - The Cold Spot (CS) at galactic coordinates (b = -57°, l = 209°) was discovered in the WilkinsonMicrowave 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 {phipe}b{phipe} > 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.

U2 - 10.1134/S199034131002001X

DO - 10.1134/S199034131002001X

M3 - Journal article

SN - 1990-3413

VL - 65

SP - 101

EP - 120

JO - Astrophysical Bulletin

JF - Astrophysical Bulletin

IS - 2

ER -

Understanding the WMAP cold spot mystery

Abstract

Access to Document

Fingerprint

Cite this