Power correlations in cosmology: limits on primordial non-Gaussian   density fields
  We probe the statistical nature of the primordial density field by measuring correlations between the power in adjacent Fourier modes. For certain types of non-Gaussian field, these k-space correlations would be expected to be more extended than for a Gaussian field, providing a useful discriminatory test for Gaussian fields. We apply this test to the combined QDOT and 1.2-Jy IRAS galaxy survey and find the observed density field to be in good agreement with having Gaussian density fluctuations for modes with k < 0.1 h/Mpc. From this result we are able to set quantitative limits on a class of possible non-Gaussian distributions -- the product of a Gaussian field with an independent stochastic field. The maximum sensitivity is to modulations of a Gaussian field with coherence scales of 30 Mpc/h and the rms modulation on this scale cannot greatly exceed unity. We discuss the improvements to this limit likely to be set by future surveys. 
A. J. Stirling and J. A. Peacock (Institute for Astronomy and Royal   Observatory, Edinburgh)