2008
DOI: 10.1111/j.1365-2966.2008.12960.x
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Testing isotropy of cosmic microwave background radiation

Abstract: We introduce new symmetry-based methods to test for isotropy in cosmic microwave background (CMB) radiation. Each angular multipole is factored into unique products of power eigenvectors, related multipoles and singular values that provide two new rotationally invariant measures mode by mode. The power entropy and directional entropy are new tests of randomness that are independent of the usual CMB power. Simulated Galactic plane contamination is readily identified. The ILC-WMAP data maps show seven axes well … Show more

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Cited by 58 publications
(89 citation statements)
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References 71 publications
(116 reference statements)
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“…It's significance is assessed using Alignment entropy. The reader may refer to Ralston & Jain (2004); Samal et al (2008) for more details about the Power tensor method, as well as it's relation to axes inferred from other statistics viz. the angular momentum dispersion maximization (de Oliveira-Costa et al 2004) and Maxwell's multipole vectors (Schwarz et al 2004).…”
Section: Power Tensor Power Entropy and Alignment Statisticsmentioning
confidence: 99%
See 1 more Smart Citation
“…It's significance is assessed using Alignment entropy. The reader may refer to Ralston & Jain (2004); Samal et al (2008) for more details about the Power tensor method, as well as it's relation to axes inferred from other statistics viz. the angular momentum dispersion maximization (de Oliveira-Costa et al 2004) and Maxwell's multipole vectors (Schwarz et al 2004).…”
Section: Power Tensor Power Entropy and Alignment Statisticsmentioning
confidence: 99%
“…The Power tensor is a robust diagnostic to test isotropy of CMB data (Ralston & Jain 2004;Samal et al 2008Samal et al , 2009. The CMB temperature is conventionally expanded in terms of spherical harmonics Y lm (n):…”
Section: Power Tensor Power Entropy and Alignment Statisticsmentioning
confidence: 99%
“…[22] data from the cosmic microwave background (CMB) was analyzed to test the "cosmological principle" requiring isotropy. The alignment of spherical harmonic multipoles and the entropy of their power distribution contradicts isotropy at a high degree of statistical significance.…”
Section: Many Experimentsmentioning
confidence: 99%
“…However, in recent years, there have been claims of anomalies detected in the CMB temperature map with considerable significance, which seem to break statistical isotropy of the temperature fluctuations and thus to question the cosmological principle. Among these anomalies, there is a strong alignment between the preferred axes of the quadrupole and the octopole, which is commonly referred to as the axis of evil [3,1,11,16,15]. The claims of the existence of a preferred direction in the CMB temperature map have led to a discussion about whether this is simply due to a chance fluctuation in the CMB temperature map, if it can be blamed on local structures or on systematics in the measurement, or whether it is actually due to a preferred direction intrinsic to the geometry of the primordial Universe [4,12,17,8,13,18,10].…”
Section: Introductionmentioning
confidence: 99%