Rj. Scherrer et Rk. Schaefer, WHEN CAN NON-GAUSSIAN DENSITY FIELDS PRODUCE A GAUSSIAN SACHS-WOLFE EFFECT, The Astrophysical journal, 446(1), 1995, pp. 44-48
The Sachs-Wolfe temperature fluctuations produced by primordial densit
y perturbations are proportional to the potential field phi, which is
a weighted integral over the density held delta. Because of the centra
l limit theorem, phi can be approximately Gaussian even when delta is
non-Gaussian. Using the Weld representation for non-Gaussian density f
ields, delta(r) = integral f(\r-r'\)Delta(r')d(3)r', we find condition
s on Delta and f for which phi must have a Gaussian one-point distribu
tion, while delta can be non-Gaussian. Sufficient (but not necessary)
conditions are that the density field have a power spectrum (which det
ermines f) of P(k) proportional to k '', with -2<n less than or equal
to+1, and that Delta(r) be non-Gaussian with no long-range correlation
s. Thus there is an infinite set of non-Gaussian density fields which
produce a nearly Gaussian one-point distribution for the Sachs-Wolfe e
ffect.