When Can Non-Gaussian Density Fields Produce a Gaussian Sachs-Wolfe Effect?
Abstract
The Sachs-Wolfe temperature fluctuations produced by primordial density perturbations are proportional to the potential field \phi, which is a weighted integral over the density field \delta. Because of the central limit theorem, \phi can be approximately Gaussian even when \delta is non-Gaussian. Using the Wold representation for non-Gaussian density fields, \delta(\rvec) = \int f(|\rvec - \rvec^\prime|) \Delta(\rvec^\prime) d^3 \rvec^\prime, we find conditions on \Delta and f for which \phi must have a Gaussian one-point distribution, while \delta can be non-Gaussian. Sufficient (but not necessary) conditions are that the density field have a power spectrum (which determines f) of P(k) \propto k^n, with -2 < n \le +1, and that \Delta(\rvec) be non-Gaussian with no long-range correlations. Thus, there is an infinite set of non-Gaussian density fields which produce a nearly Gaussian one-point distribution for the Sachs-Wolfe effect.
Keywords
Cite
@article{arxiv.astro-ph/9407089,
title = {When Can Non-Gaussian Density Fields Produce a Gaussian Sachs-Wolfe Effect?},
author = {Robert J. Scherrer and Robert K. Schaefer},
journal= {arXiv preprint arXiv:astro-ph/9407089},
year = {2011}
}
Comments
13 pages + 4 figs., uuencoded, compressed postscript files, (Repaired error in uudecode unpacking.)