Probing non-Gaussianities on Large Scales in WMAP5 and WMAP7 Data using Surrogates

Understand

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.