  Recent Cosmic Microwave Background (CMB) observations indicate that the
temperature anisotropies arise from quantum fluctuations in the inflationary
scenario. In the simplest inflationary models, the distribution of CMB
temperature fluctuations should be Gaussian. However, non-Gaussian signatures
can be present. They might have different origins and thus different
statistical and morphological characteristics.
  In this context and motivated by recent and future CMB experiments, we search
for, and discriminate between, different non-Gaussian signatures. We analyse
simulated maps of three cosmological sources of temperature anisotropies:
Gaussian distributed CMB anisotropies from inflation, temperature fluctuations
from cosmic strings and anisotropies due to the kinetic Sunyaev-Zel'dovich (SZ)
effect both showing a non-Gaussian character. We use different multi-scale
methods, namely, wavelet, ridgelet and curvelet transforms. The sensitivity and
the discriminating power of the methods is evaluated using simulated data sets.
  We find that the bi-orthogonal wavelet transform is the most powerful for the
detection of non-Gaussian signatures and that the curvelet and ridgelet
transforms characterise quite precisely and exclusively the cosmic strings.
They allow us thus to detect them in a mixture of CMB + SZ + cosmic strings. We
show that not one method only should be applied to understand non-Gaussianity
but rather a set of different robust and complementary methods should be used.

Astrophysics