Skip to Main content Skip to Navigation
Theses

SYSTEMES D'ABSORPTION DANS LE SPECTRE DES QUASARS: CINEMATIQUE, METALLICITE, EVOLUTION COSMOLOGIQUE

Abstract : Absorption line systems observed at high resolution in the spectrum of background quasars are powerful tools for studying the baryonic gas content of the Universe and its evolution. Whereas the diffuse gas clouds of the intergalactic medium, the so-called Lyman-alpha forest, dominate the mass density of baryons at high redshift, the damped Lyman-alpha systems with their large neutral hydrogen column densities dominate the mass density of neutral gas at any redshift. The latter are probably associated to important steps in the formation and evolution of galaxies. In this thesis, I present works whose aim is to better determine the physical properties and constrain the nature of the damped Lyman-alpha systems. After an introduction and a review of our knowledge in the field, I describe my analysis of the chemical abundances and kinematics of the neutral gas at high redshift. I then investigate the connection between those objects and the optical identification of the absorbing galaxies at intermediate redshift by studying the nucleosynthesis history of the gas and the possible existence of dust grains at z_abs less than 1.7. Moreover, the application of the technics of integral field spectroscopy enabled me to search for Lyman-alpha emission from star-forming regions associated to the highest redshift damped Lyman-alpha systems, emission that I interpret in the framework of a physical model of damped Lyman-alpha systems. Finally, the last part of the thesis is devoted to a project aiming at the study of the association of the Lyman-alpha forest clouds with large-scale structures and galactic haloes at low redshift, and I present in this context the results of an efficient survey of bright quasars in the background of the Coma cluster of galaxies.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00003228
Contributor : Ledoux Cédric <>
Submitted on : Sunday, August 3, 2003 - 12:05:54 AM
Last modification on : Thursday, April 23, 2020 - 2:26:29 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 9:25:10 PM

Identifiers

  • HAL Id : tel-00003228, version 1

Collections

Citation

Cédric Ledoux. SYSTEMES D'ABSORPTION DANS LE SPECTRE DES QUASARS: CINEMATIQUE, METALLICITE, EVOLUTION COSMOLOGIQUE. Astrophysique [astro-ph]. Université Claude Bernard - Lyon I, 1999. Français. ⟨tel-00003228⟩

Share

Metrics

Record views

339

Files downloads

189