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Modélisation des spectres des Supernovas de Type Ia observés par la collaboration The Nearby Supernova Factory dans le but d’améliorer les mesures de distances extragalactiques

Abstract : At the end of the 90s, two independent teams showed, based on distance measurements of type Ia supernovæ (SNIa), that expansion of our Universe is accelerating. Since then, one of the priorities of modern cosmology is to characterize this phenomenon and to understand its nature. The improvement of distance measurements of SNIa is one technique to improve the constraints on acceleration and to determine the physical nature of it. This document develops a new SNIa spectral energy distribution model, called the Supernova Useful Generator and Reconstructor (SUGAR), which improves distance measurement. This model is constructed from SNIa spectral properties and spectrophotometric data from The Nearby Supernova Factory collaboration. The main advancement proposed in SUGAR is the addition of two additional parameters to characterize the SNIa variability. The first depends on the properties of SNIa ejecta velocity, the second depends on their calcium lines. The addition of these parameters as well as the high quality of the data of The Nearby Supernova Factory collaboration make SUGAR the best model available to describe the spectral energy distribution of SNIa and improves distances measurements of the order of 15 % relative to the usual method. The performance of this model makes it an excellent candidate for preparing future experiments like LSST or WFIRST. In addition, this document presents an analysis of the effect of SNIa belonging to a galaxy cluster on its distance measurement. Galaxies of a cluster have a peculiar velocity much higher than the assumed value when measuring distances with SNIa. This has the effect of introducing a systematic error into the distance measurement. Failure to take into account this effect may degrade the distance measurement by 2.5% for SNIa belonging to a cluster. This analysis was carried out using data from the collaboration of the Nearby Supernova Factory and public catalogs of galaxy cluster.
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https://tel.archives-ouvertes.fr/tel-01467899
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Submitted on : Friday, February 17, 2017 - 2:08:44 PM
Last modification on : Thursday, February 25, 2021 - 10:58:36 AM
Long-term archiving on: : Thursday, May 18, 2017 - 1:03:38 PM

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  • HAL Id : tel-01467899, version 1

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Pierre-François Léget. Modélisation des spectres des Supernovas de Type Ia observés par la collaboration The Nearby Supernova Factory dans le but d’améliorer les mesures de distances extragalactiques. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Blaise Pascal, 2016. Français. ⟨NNT : 2016CLF22730⟩. ⟨tel-01467899⟩

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