1.*
Department of Astrophysical Sciences, Princeton University,
Princeton, NJ 08544, USA*

Abstract

The Wilkinson Microwave Anisotropy Probe (*WMAP*) has made
it possible to test Gaussianity of fluctuations in
the cosmic microwave background with unprecedented sensitivity,
thanks to its careful instrumental design minimizing systematic errors.
Constraints on the CMB non-Gaussianity offer a fundamental test of
inflation and general relativistic perturbation theory.
On the other hand, extragalactic radio sources produce significant
non-Gaussian signals, making physical interpretations of the measured
non-Gaussianity complex. Applying to the *WMAP* 1-year data a
statistical tool we have developed for separately measuring the
primordial and the source non-Gaussianities, we find:
(1) CMB is consistent with Gaussian fluctuations,
as predicted by inflation. The r.m.s. contribution from a second order
(non-linear) term is smaller than 2x10^{-5} of the leading term.
Note that the second-order perturbation theory predicts 10-100
times smaller value.
(2) We have detected the source contribution at 41GHz (Q band);
thus, the *WMAP* map in Q band **is** weakly non-Gaussian
at small angular scales because of the sources!
This measurement has been used to determine the source contribution
to the power spectrum in Q band.
Our method can be applied to
the Planck experiment, for which there is a chance to detect
non-Gaussianity predicted by the second-order perturbation theory.

Please Contact Me !!

Mail: ekomatsu@princeton.edu