Dresden 2003 – scientific programme

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DY: Dynamik und Statistische Physik

DY 36: Nonlinear dynamics II

DY 36.5: Talk

Wednesday, March 26, 2003, 17:30–17:45, G\"OR/226

Identifying Non-Gaussian Signatures in Cosmic Microwave Background Maps: An Application for the Method of Surrogates — •Christoph Räth and Peter Schuecker — Centre for Interdisciplinary Plasma Sciences (CIPS)/ Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr., 85741 Garching

The identification of non-Gaussian signatures in cosmic microwave background (CMB) temperature maps is one of the main cosmological challenges today, because it allows to discriminate between different cosmological models.

We extend the well known method of surrogate data to the case of two-dimensional images for designing statistical methods in order to test for non-Gaussianity in CMB maps. Using a two-dimensional version of the ITAAFT algorithm surrogate maps are generated, which mimic both the power spectrum and the amplitude distribution of simulated CMB maps containing non-Gaussian signals while all higher order correlations are wiped out. Analysing all maps with measures sensitive to these higher order correlations (e.g. weighted scaling indices, Minkowski functionals) leads to a statistically highly significant discrimination between the surrogate and original maps. Thus a clear detection of non-Gaussian signatures is made possible.

We also show that this approach is very robust with respect to superimposed additive white noise and that one can detect non-Gaussianity at higher noise level as with other techniques recently proposed (e.g. mapping of the Fourier phases).