No large-angle correlations on the non-Galactic microwave sky

Understand

We investigate the angular two-point correlation function of temperature in the WMAP maps.

• Updating and extending earlier results, we confirm the lack of correlations outside the Galaxy on angular scales greater than about 60 degrees at a level that would occur in 0.025 per cent of realizations of the concordance model.
• This represents a dramatic increase in significance from the original observations by the COBE-DMR and a marked increase in significance from the first-year WMAP maps.
• Given the rest of the reported angular power spectrum C_\ell, the lack of large-angle correlations that one infers outside the plane of the Galaxy requires covariance among the C_\ell up to \ell=5.