Evidence of Vorticity and Shear at Large Angular Scales in the WMAP Data: A Violation of Cosmological Isotropy?

By T. Jaffe, A. Banday, H. Eriksen, K. G'orski, F. Hansen. 2005

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Motivated by the large-scale asymmetry observed in the cosmic microwave background sky, we consider a specific class of anisotropic cosmological models—Bianchi type VIIh—and compare them to the WMAP first-year data on large angular scales. Remarkably, we find evidence of a correlation that is ruled out as a chance alignment at the 3 σ level. The best-fit Bianchi model corresponds to x = 0.55, Ω0 = 0.5, a rotation axis in the direction (l, b) = (222°, -62°), shear 0 = 2.4 × 10-10, and a right-handed vorticity 0 = 4.3 × 10-10. Correcting for this component greatly reduces the significance of the large-scale power asymmetry, resolves several anomalies detected on large angular scales (i.e., the low quadrupole amplitude and quadrupole/octopole planarity and alignment), and can account for a non-Gaussian "cold spot" on the sky. Despite the apparent inconsistency with the best-fit parameters required in inflationary models to account for the acoustic peaks, we consider the results sufficiently provocative to merit further consideration.

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/1a42f375bbb20781ce31fea7352987aafc1f3399

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Citations in the corpus

Accelerating Cosmologies with an Anisotropic Equation of State (2007, background): “…that CMB spectrum of the tilted B(VIIh) background (Hawking 1968; Barrow et al. 1985; Pontzen and Challinor 2007) would have potential to model these anomalies (Jaffe et al. 2005) were it not in conflict with a dark energy dominated universe at the smaller angular scales (Jaffe et al. 2006).”
Hemispherical Power Asymmetry in the Third-Year Wilkinson Microwave Anisotropy Probe Sky Maps (2007, background): “Similar arguments could possibly also be made for the Bianchi VIIh correlation found by Jaffe et al. (2005).”
Gauge fields and inflation (2012, background): “These “anomalies” include non-Gaussianity which we already discussed, a low power in the quadrapole moment [35, 36], the alignment of the lower multipoles [37], a five-degree scale cold spot with suppressed power [38], an asymmetry in power between the Northern and Southern ecliptic hemisphere [39],”
The large-scale structure of the Universe (2006, background): “Although these signals could perhaps originate from foregrounds or residual systematics, it is curious that the anomalies seem well matched by anisotropic Bianchi cosmological models, although the models examined so far require unacceptable cosmological parameter value”
The non‐Gaussian cold spot in Wilkinson Microwave Anisotropy Probe: significance, morphology and foreground contribution (2006, background): “Nevertheless a later work, Jaffe et al. (2005b), seems to indicate the incompatibility of the WMAP data with extended Bianchi models including a dark energy term.”
INCREASING EVIDENCE FOR HEMISPHERICAL POWER ASYMMETRY IN THE FIVE-YEAR WMAP DATA (2009, background): “…grown very large, indeed (e.g., Bernui et al. 2006; Bielewicz et al. 2005; Copi et al. 2006; Cruz et al. 2005, 2006; Eriksen et al. 2004b,c, 2005; Jaffe et al. 2005, 2006; Mart́ınez-González et al. 2006; McEwen et al. 2008; Räth et al. 2007; Yadav & Wandelt 2008), and it would be unwise not to…”
Mapping extreme-scale alignments of quasar polarization vectors (2005, background): “Recent analyses of WMAP data indicate that several largescale anisotropies in the CMB are possibly related to this di- 8 In principle, the redshift dependence of the mean polarization angle may also be a colour effect rather than a distance effect because we are sampling quasar rest-frame spectra at”
Local Voids as the Origin of Large-Angle Cosmic Microwave Background Anomalies. I. (2006, methodology): “Luminet et al. (2003) proposed a nontrivial spherical topology to explain the low quadrupole, and Jaffe et al. (2005) considered a locally anisotropic model based on the Bianchi type VIIh universe to explain the quadrupole-octopole planarity and alignment.”