Forecasts on the contamination induced by unresolved point sources in
  primordial non-Gaussianity beyond Planck
  In this paper we present forecasts of the contamination on different shapes
of the primordial non-Gaussianity fnl parameter -- detectable on future Cosmic
Microwave Background (CMB) high--resolution anisotropy maps -- produced by
unresolved extragalactic point sources at frequencies of cosmological interest
(45--375 GHz). We consider two scenarios: an ideal (noiseless) mission and a
possible future space-borne satellite, with instrumental characteristics
similar to the ones proposed for the Cosmic Origins Explorer (COrE). The local,
equilateral, orthogonal and flat shapes are considered in both temperature
(intensity) and polarized emission data. The angular power spectrum and
bispectrum of extragalactic point sources are estimated by state-of-the-art
models of source number counts. The impact of all the most relevant (far--IR
and radio selected) source populations on these shapes at COrE frequencies is
studied. The results of this analysis show that unresolved extragalactic point
sources should not induce a very relevant non-Gaussian signal in the frequency
range 100--200 GHz, thus not preventing a correct estimate of the CMB
primordial fnl parameter. Polarization information allows one to significantly
reduce the error--bars in the fnl parameter and the bias induced by unresolved
sources and, hence, to widen the range of frequencies for fnl studies. On the
contrary, at nu < 100 GHz or nu > 225 GHz, important non-Gaussian deviations in
CMB anisotropy maps are expected due to unresolved extragalactic sources.
