Spectroscopie des supernovæ à grand décalage vers le rouge

Abstract : This thesis allowed to compare the spectral features of type Ia supernovae in function of the redshift ("evolution"). Within the collaboration of the Supernova Cosmology Project (SCP) and the SuperNova Legacy Survey (SNLS), which both aim at discovering highly redshifted type Ia supernovae, a large fraction of this thesis is devoted to the spectral data reduction. One used to work on the reduction of the whole set of data from the échellettes spectrograph ESI mounted on the focus of the 10 meters class telescope Keck obtained by the SCP. Hence, we got some type Ia supernovae among the farthest ever observed. I also worked on the reduction of the spectral data from the SNLS experiment, mainly obtained with the long-slit spectrograph FORS1 mounted on VLT. SNLS has to reduce and identify about ten spectra per moon phase during 5 years. In the framework of this thesis, a software has been developed. It is able to estimate simultaneously the type, the redshift and the phase of the candidate.
It's also possible to fit the fraction (and the morphological type) of host galaxy contaminating the studied spectrum. The software has been tested in very details on a sample of candidates from the SNLS. Using these spectra, one measured the velocity of the calcium CaH&K ($\lambda$ 3945.12Å) into the supernova photosphere and compared the results with the same measurements done on a sample of local type Ia supernovae. The comparison confirmed the homogeneity of the high redshifted type Ia supernovae. It's fundamental to measure cosmological parameters with type Ia supernovae.
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• HAL Id : tel-00106153, version 1

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Grégory Sainton. Spectroscopie des supernovæ à grand décalage vers le rouge. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Claude Bernard - Lyon I, 2004. Français. ⟨tel-00106153⟩

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