A&A 416, 9-17 (2004)
Detection and discrimination of cosmological non-Gaussian signatures
by multi-scale methods
J.-L. Starck1, N. Aghanim2 and O. Forni2
DAPNIA/SEDI-SAP, Service d'Astrophysique, CEA-Saclay,
91191 Gif-sur-Yvette Cedex, France
IAS-CNRS, Université Paris Sud, Bâtiment 121, 91405, Orsay Cedex, France
(Received 19 February 2003 / Accepted 6 November 2003)
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
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
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.
cosmology: cosmic microwave background --
cosmology: early universe --
methods: data analysis
Offprint request: J.-L. Starck, firstname.lastname@example.org
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