The WMAP cosmic microwave background (CMB) first year data was anomalously smooth on the largest spatial scales. We have recently shown that spatial fluctuations in the dark energy, that is causing the expansion of the Universe to speed up, may partially cancel the fluctuations in the CMB on the largest scales. This would imply that the residual fluctuations that are observed on large scales would be due to the integrated Sachs Wolfe effect which is caused by the effect of large scale structure on the CMB at a redshift of about 1. We found that the current WMAP data provides a two sigma detection of the dark energy fluctuations. As this effect only operates at and after about redshift of one, we predict that the EE polarization fluctuations will be unsuppressed on large scales. We also discuss possible inflationary mechanisms for generating the dark energy fluctuations.
Reference: Christopher Gordon, Wayne Hu, astro-ph/0406496