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PROPRIETES DES PREMIERES ETOILES ET GALAXIES. CONTRAINTES SUR LES MODELES DE FORMATION DES GALAXIES

Abstract : Reionization is one of the latest frontiers in modern cosmology. The first stars and galaxies formed during this epoch marked the end of the “Dark Ages” of the Universe, as well as the reionization of the intergalactic medium. The nature and formation epoch of these sources are still not well-known, and their study is motivating many future instrumental projects (JWST, EMIR/GTC, KMOS/VLT, ...) for which developments need advanced feasibility studies.

This thesis work is based on the data analysis from three main observational projects aimed at the detection and study of extremely distant astrophysical sources. Considerations on the detection limits of individual objects using present-day facilities lead us to the use of galaxy clusters as gravitational lenses, thus taking benefit of the magnification effect.

I first introduce the topic of this thesis: the cosmological context, properties of the distant Universe and gravitational lensing.

I will then present three main observational projects on which this thesis is based:

· A search for Lyman-alpha emitters using blind spectroscopy of the most magnified regions of a galaxy clusters sample. From the resulting detections, we derive constraints on the Lyman-alpha luminosity function, at much fainter luminosities than other studies at similar redshift.

· A detailed study on one particular distant (z~7) galaxy, observed by HST and Spitzer space telescopes. Photometric properties of this source suggest the presence of a relatively evolved stellar population at this epoch.
· A photometric research project for extremely distant objects, carried out using VLT telescopes in the near-infrared. Details on the photometric analysis and obtained spectroscopic results for several candidates are particularly stressed out. Studying the whole sample of candidates enables us to give constraints on the ultraviolet luminosity function and the cosmic star formation rate in this redshift domain.

All these results bring additional elements for the general description of the reionization epoch, that can be compared with theoretical predictions.
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https://tel.archives-ouvertes.fr/tel-00011648
Contributor : Williams Exbrayat <>
Submitted on : Monday, February 20, 2006 - 3:14:54 PM
Last modification on : Saturday, November 28, 2020 - 4:20:02 AM
Long-term archiving on: : Saturday, April 3, 2010 - 8:42:37 PM

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  • HAL Id : tel-00011648, version 1

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Johan Richard. PROPRIETES DES PREMIERES ETOILES ET GALAXIES. CONTRAINTES SUR LES MODELES DE FORMATION DES GALAXIES. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2005. Français. ⟨tel-00011648⟩

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