Probing non-Gaussianities on Large Scales in WMAP5 and WMAP7 Data using
  Surrogates
  Probing Gaussianity represents one of the key questions in modern cosmology,
because it allows to discriminate between different models of inflation. We
test for large-scale non-Gaussianities in the cosmic microwave background (CMB)
in a model-independent way. To this end, so-called first and second order
surrogates are generated by first shuffling the Fourier phases belonging to the
scales not of interest and then shuffling the remaining phases for the length
scales under study. Using scaling indices as test statistics we find highly
significant signatures for both non-Gaussianities and asymmetries on large
scales for the WMAP data of the CMB. We find remarkably similar results when
analyzing different ILC-maps based on the WMAP five and seven year data. Such
features being independent from the map-making procedure would disfavor the
fundamental principle of isotropy as well as canonical single-field slow-roll
inflation - unless there is some undiscovered systematic error in the
collection or reduction of the CMB data or yet unknown foreground
contributions.
