Infrared galaxies : spatial distribution, contribution to the extragalactic background and spectral energy distribution

If the formation of large scale structures is rather well understood, the question of galaxies formation and evolution still remains open. In particular, there is a need to understand how the stars are formed in galaxies. Studying infrared luminous galaxies can help to answer these questions. In this thesis work, we have mainly used infrared data from the Spitzer satellite.<br /><br />The first part of this work deals with the study of infrared galaxies spatial distribution. We introduce a new method to estimate the angular correlation function of galaxies. This method has been validated both on simulations and data. We also show how these spatial correlation effects might bias mean flux measurement when using a stacking analysis. Moreover, the angular correlation function measured on galaxies selected at 3.6 or 24 microns shows an excess of correlation at small angular<br />scales. This could be linked with the interaction of galaxies inside dark matter halos which might be at the origin of the infrared emission.<br /><br />Then, we endeavour to better caracterize the Cosmic Infrared Background (CIB) thanks to a determination of the contribution of galaxies detected at 3.6 microns and by comparing it to the one of the galaxies selected at 24 microns. We also estimate the contribution to the CIB at 3.6 and 24 microns of sources selected at 3.6 microns as a function of their specific star formation rate.<br /><br />Finally, we study the spectral energy distribution of a large number of galaxies located between z=0 and z=2 : on the one hand we show that the 8 microns and 24 microns luminosities are good tracers of the total infrared luminosity, and thus of the star formation rate, and on the other hand, that the properties of these galaxies do not seem to evoluate between z=0 and z=1. We also analyse in detail 17 spectra of infrared galaxies selected at 70 microns and we show that the relative luminosity of aromatic molecules decreases with an increasing radiation field.