Imagerie et spectro-imagerie X appliquees a l'etude des proprietes du milieu intergalactique dans les amas de galaxies en cours de coalescence.

Abstract : Clusters of galaxies are gravitationally bound matter over-densities
which are filled with a hot and ionized gas emitting in X-rays. They
form during merging phases of subgroups, so that the gas
undergoes shock and mixing processes which perturb its physical
properties at hydrostatic equilibrium. In order to map the spatial
distributions of the gas emissivity, temperature and entropy as
observed by X-ray telescopes, we compared different multi-scale
imaging algorithms, and also developed and tested a new
multi-scale spectral-mapping algorithm. With this algorithm, the
searched parameter is first estimated from a count statistics within
different spatial resolution elements, and its space-frequency
variations are then coded by Haar wavelet coefficients. The optimal
spatial distribution of the parameter is finally restored by
thresholding the noisy wavelet transform.
Document type :
Theses
Astrophysics [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2004. French


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Contributor : Herve Bourdin <>
Submitted on : Monday, January 2, 2006 - 12:02:55 PM
Last modification on : Monday, January 2, 2006 - 6:37:24 PM

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Herve Bourdin. Imagerie et spectro-imagerie X appliquees a l'etude des proprietes du milieu intergalactique dans les amas de galaxies en cours de coalescence.. Astrophysics [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2004. French. <tel-00011275>

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