Lack of large-angle TT correlations persists in WMAP and Planck

The lack of large-angle correlations in the observed microwave backgroundtemperature fluctuations persists in the final-year maps from WMAP and thefirst cosmological data release from Planck. We find a statistically robust andsignificant result: p-values for the missing correlations lying below 0.24 percent (i.e. evidence at more than 3 sigma) for foreground cleaned maps, incomplete agreement with previous analyses based upon earlier WMAP data. Aconservative cut-sky analysis of the Planck HFI 100 GHz frequency band, the`cleanest CMB channel', returns a p-value as small as 0.03 per cent, based onthe conservative mask defined by WMAP. These findings are in stark contrast toexpectations from the inflationary Lambda cold dark matter model and still lacka convincing explanation. If this lack of large-angle correlations is a truefeature of our Universe, and not just a statistical fluke, then thecosmological dipole must be considerably smaller than that predicted in thebest-fitting model.