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CONTRAINTES COSMOLOGIQUES DEDUITES DES EFFETS DE LENTILLE GRAVITATIONNELLE DANS LES AMAS DE GALAXIES

Abstract : I use cluster-lenses containing several multiple-imaged systems of background galaxies to constrain the cosmological parameters. Indeed, the model of the cluster of galaxies gravitational potential is then precise enough to get constraints on the distances between sources and images. These distances directly depend on the Universe geometry, which is fixed by the cosmological parameters (ie the Universe matter density, the cosmological constant and dark energy in general). This method requires precise parametric models of gravitational potentials. I developped a general formalism of pseudo elliptical profiles, giving analytical expressions for lensing quantities. I first study the errors semi analytically, to get the expected accuracy. Numerical simulations of of typical cluster-lenses complete this preliminary work. I can then precise the potential optimisation method and exhibit the expected degeneracy between the cosmological parameters. This process is then applied to the clusters of galaxies A2218 and AC114. The Universe geometry I get is fully compatible with the actual cosmological standard model. The degeneracies can be broken by combining these results with independant cosmological tests. Eventually, the potential optimisation process leads to a very precise modeling of these two clusters mass distribution. Their central density is especially flat. This cosmological test requires the precise knowledge of each image redshift. I then observed spectroscopically with the VLT gravitational arcs in the A1689 cluster of galaxies, which is an excellent candidate for the proposed test.
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https://tel.archives-ouvertes.fr/tel-00002279
Contributor : Ghislain Golse <>
Submitted on : Thursday, January 16, 2003 - 8:05:34 PM
Last modification on : Monday, April 5, 2021 - 2:26:05 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 7:30:18 PM

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  • HAL Id : tel-00002279, version 1

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Ghislain Golse. CONTRAINTES COSMOLOGIQUES DEDUITES DES EFFETS DE LENTILLE GRAVITATIONNELLE DANS LES AMAS DE GALAXIES. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2002. Français. ⟨tel-00002279⟩

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