The complete bispectrum of COBE-DMR four-year maps.

We extend a previous bispectrum analysis of the COBE-DMR four-year maps, allowing for the presence of correlations between all possible angular scales. For reasons of presentation we restrict ourselves to triplets of modes symmetrically arranged, but with larger and larger ℓ separation. We find that the non-Gaussian signal found earlier for bispectrum components including adjacent modes does not extend to triplets of modes with larger separations. Indeed for all separations Δℓ>1 we find that the COBE-DMR data are very Gaussian. The implication seems to be that the previously detected non-Gaussian scale–scale correlation falls off very quickly with mode separation. [ABSTRACT FROM AUTHOR]