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Recherche d'effets de microlentille gravitationnelle vers le centre galactique avec les données d'EROS-II

Abstract : The systematic search for gravitational microlensing effect towards the galactic center makes it possible to probe the galactic structure. The thesis work presented here concerns the analysis of all galactic center data collected by the Eros2 experiment during 7 years (1996-2003) : the survey of 66 square degrees located on both sides of the galactic plane has allowed to build the lightcurves of approximately 50 million stars in two filters. Gravitational microlensing events with a duration ranging between 4 days and 500 days and whose maximum magnification is higher than 2.18 were required ; this makes it possible to select convincing candidates and constitutes an originality compared to the previous analyses (Eros2 and other experiment) where maximum magnification was required to be higher than 1.34. The analysis revealed 139 microlensing candidates. This sample contains 91 candidates whose source is a clump red giant star with an associated detection efficiency of 56%. The optical depth obtained for the clump red giant sources is (1,79 +/- 0,20).10e-6. This value is in good agreement with predicted values as well as with the latest result of the Macho group but it is lower than the Ogle and Moa group results which are 2 to 3 times higher than the predicted one. In addition, the large statistics of galactic center data collected by Eros2 made it possible to calculate the optical depth for various galactic latitudes, and to detect the gradient of optical depth expected in galactic models.
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Contributor : Clarisse Hamadache <>
Submitted on : Friday, March 25, 2005 - 10:03:31 PM
Last modification on : Monday, February 10, 2020 - 6:12:47 PM
Long-term archiving on: : Friday, September 14, 2012 - 12:15:18 PM


  • HAL Id : tel-00008874, version 1



Clarisse Hamadache. Recherche d'effets de microlentille gravitationnelle vers le centre galactique avec les données d'EROS-II. Astrophysique [astro-ph]. Université Louis Pasteur - Strasbourg I, 2004. Français. ⟨tel-00008874⟩



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