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Etudes autour des anisotropies du corps noir cosmologique et des amas de galaxies

Abstract : In order to account for the formation of the well known large scale structures of the Universe, the current cosmological paradigm relies on the instability of the Friedman-Lemaitre model with respect to inhomogeities in the energy density. In this theoretical framework, these inhomogeneities have been predicted, and later observed, to give rise to temperature anisotropies in a millimetric cosmological background radiation (CMB), otherwise thermalized at 3K, which is homogeneous and isotropic. By observing these anisotropies with ever increasing higher sensitivity, present and future CMB experiments like ARCHEOPS, TopHat or PLANCK, hope to test this paradigm with tantalizing precision. However, these experiments entail some unprecedented data-analysis challenges. To overcome some of these issues, we developped a fast multigrid algorithm for making maps of temperature fluctuations from time-ordered data, a power spectrum estimation algorithm via hierarchical decomposition, an analytical modeling of the effects induced by an axisymetric intrumental beam and an original and sensitive statistic to detect a would-be non-Gausian component in the statistical distribution of these fluctuations. Furthermore, looking further down in time at these inhomogeneities, we can distinguish clusters of galaxies amid large scale structures. We also studied these systems, the largest gravitationaly bound systems today. In particular, we developped an analytic model that allows to take into account a non-gravitational heating, whose observational consequences are important. At last, we were able to describe in a more satisfying manner the baryonic content of these clusters by making use of a joint analysis of gravitational distortion observations and, Sunyaev-Zel'dovich effect and X-ray emission measurements, both originating from the hot intra-cluster gas.
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Contributor : Olivier Dore <>
Submitted on : Monday, July 14, 2003 - 5:02:39 PM
Last modification on : Wednesday, December 9, 2020 - 3:05:26 PM
Long-term archiving on: : Friday, April 2, 2010 - 8:12:39 PM


  • HAL Id : tel-00003122, version 1


Olivier Dore. Etudes autour des anisotropies du corps noir cosmologique et des amas de galaxies. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2001. Français. ⟨tel-00003122⟩



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