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Les naines brunes dans les relevés grand champ

Abstract : My PhD research work, under the supervision of Thierry Forveille and Xavier Delfosse at the laboratoire d'astrophysique de Grenoble, is centered on identifying brown dwarfs in a new-generation wide-field survey, the Canada-France Brown Dwarfs Survey -CFBDS-. Its main goals are to identify cooler and low metallicity brown dwarfs for detailed study, and to assemble a large sample of more ordinary brown dwarfs for statistical analyses. My role, as the only full-time member of this international collaboration, included the programming of an analysis and selection pipeline to identify the rare brown dwarf candidates in the very large image database, as well as coordination of the internation collaboration.
Chapter 1 summarizes the state of brown dwarf science at the start of this PhD. Chapter 2 presents the Canada-France Brown Dwarfs and our analysis strategy. Chapter 3 describes the pipeline I developed to optimally identify the few interesting brown dwarfs (as well as high redshift quasars) candidates among the many millions of less interesting astrophysical sources in the CFBDS images. This chapter also describes the Point Spread Function -PSF- fitting module which I added to the well known Source Extractor image analysis package.Chapter 4 presents the resulting brown dwarf candidates, assesses the statistical biases of the CFBDS survey, and evaluates the associated field brown dwarfs luminosity function.
Finally, Chapter 5 briefly reviews the physical informations which can be extracted from brown dwarfs spectra, and examines in that light the spectra which we obtained for two dozen of our candidates. It ends with discussions of our discovery of the coolest browndwarf published to date, CFBDS0059, and of what is likely the first T subdwarf.
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Submitted on : Thursday, January 8, 2009 - 11:01:23 AM
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Philippe Delorme. Les naines brunes dans les relevés grand champ. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2008. Français. ⟨tel-00351010⟩

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