Uncorrelated universe: Statistical anisotropy and the vanishing angular correlation function in WMAP years 1 3

By C. Copi, D. Huterer, D. Schwarz, Glenn Starkman. 2006

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The large-angle (low-l) correlations of the cosmic microwave background (CMB) as reported by the Wilkinson Microwave Anisotropy Probe (WMAP) after their first year of observations exhibited statistically significant anomalies compared to the predictions of the standard inflationary big-bang model. We suggested then that these implied the presence of a solar system foreground, a systematic correlated with solar system geometry, or both. We reexamine these anomalies for the data from the first three years of WMAP's operation. We show that, despite the identification by the WMAP team of a systematic correlated with the equinoxes and the ecliptic, the anomalies in the first-year internal linear combination (ILC) map persist in the three-year ILC map, in all-but-one case at similar statistical significance. The three-year ILC quadrupole and octopole therefore remain inconsistent with statistical isotropy - they are correlated with each other (99.6% C.L.), and there are statistically significant correlations with local geometry, especially that of the solar system. The angular two-point correlation function at scales > 60 deg in the regions outside the (kp0) galactic cut, where it is most reliably determined, is approximately zero in all wavebands and is even more discrepant with the best-fit Lambda CDM inflationary model than in the first-year data - 99.97% C.L. for the new ILC map. The full-sky ILC map, on the other hand, has a nonvanishing angular two-point correlation function, apparently driven by the region inside the cut, but which does not agree better with Lambda CDM. The role of the newly-identified low-l systematics is more puzzling than reassuring.

Subfields: Applied Mathematics, Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/bb0a11493ec4bd1eb0d09388a81c1772cbc9576a

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Citations in the corpus

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],”
Small scale problems of the $\Lambda$CDM model: a short review (2016, methodology): “s. This is shown in Fig.14. Both the left, and right panels display RCs with Vmax < 24km/s while simulations have much larger values. Rotation curves obtained from NFW-shaped subhaloes with Vmax = (12,18,24,40)km/s, with a 1 s scatter, taken from Aquarius simulations, present the simulation side ”
FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2008, unknown): “…et al. 2003; Larson & Wandelt 2004; Eriksen et al. 2004; Eriksen et al. 2004; Eriksen et al. 2004, 2007a; Copi et al. 2004; Schwarz et al. 2004; Copi et al. 2006, 2007; Gordon et al. 2005; Bielewicz et al. 2005; Jaffe et al. 2005, 2006; Vielva et al. 2004; Cruz et al. 2005, 2006, 2007b,a;…”
Probing the anisotropic local Universe and beyond with SNe Ia data (2010, background): “…of anomalies in large-angle anisotropies in the CMB, e.g. the hemispherical asymmetry (Eriksen et al. 2004) and the unexpected quadrupole–octupole alignment (de Oliveira-Costa et al. 2004), have led many to question whether the CMB is indeed statistically isotropic (e.g. Copi et al. 2007).”
(An)isotropy of the Hubble diagram: comparing hemispheres (2007, methodology): “A similar study has been used by Eriksen et al. (2004) to analyse the cosmic microwave sky, which led to one of the several anomalies discovered in the WMAP data (see Copi et al. 2007 for a recent update and summary).”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “, the CMB parity breaking has been recently linked to the lack of large-scale power [827, 340, 669].”
No large-angle correlations on the non-Galactic microwave sky (2008, methodology): “We have clarified the relation between various definitions of the angular correlation function, and revisited our previous calculation from Copi et al. (2007) in more detail.”
SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: ARE THERE COSMIC MICROWAVE BACKGROUND ANOMALIES? (2010, background): “It now appears that the Spergel et al. (2003) and Copi et al. (2007, 2009) low pvalues result from both the a posteriori definition of S1/2 and a chance alignment of the Galactic plane with the 7 CMB signal.”
Large-Angle Anomalies in the CMB (2010, methodology): “[14, 25], we investigated the quadrupoleoctopole shape and orientation using the multipole vectors.”
POWER ASYMMETRY IN WMAP AND PLANCK TEMPERATURE SKY MAPS AS MEASURED BY A LOCAL VARIANCE ESTIMATOR (2014, unknown): “…Vielva et al. 2004; Larson & Wandelt 2004; Land & Magueijo 2005a, 2005b, 2007; McEwen et al. 2005, 2006; Jaffe et al. 2006; Hinshaw et al. 2007; Spergel et al. 2007; Cruz et al. 2007; Bridges et al. 2007; Copi et al. 2007; Bernui et al. 2007; Bernui & Hipolito-Ricaldi 2008; Pietrobon et al. 2008).”