This thesis investigates how galaxies form and what diversifies the evolutionary histories of galaxies. The first part of this thesis describes the identification of luminous galaxies in the early... Show moreThis thesis investigates how galaxies form and what diversifies the evolutionary histories of galaxies. The first part of this thesis describes the identification of luminous galaxies in the early Universe and the follow-up study of their properties with the Very Large Telescope, ALMA and the Hubble Space Telescope. Luminous galaxies are assembling through merging of multiple components and heavy elements as carbon are already in place relatively shortly after galaxies have formed. The second part describes the study of the Lyman-alpha escape fraction of galaxies at the peak of star formation history. The Lyman-alpha escape fraction is generally low, except for rare massive galaxies with AGN activity or for low mass galaxies. This implies that Lyman-alpha radiation escapes more efficiently in the early Universe, when galaxies tend to be less massive with a lower dust content. The final part of this thesis is a theoretical investigation of the co-evolution of dark matter halos and galaxies in the cosmological hydrodynamical EAGLE simulation. Galaxy stellar mass growth is driven by both the mass and formation time of dark matter halos. As a result, present-day growth rates of galaxies are coherent with the long time-scale histories. Show less
