Preview

PDF, English Download (41MB) | Terms of use

Abstract

Galaxies grow in stellar mass either by turning their gas into stars, or by merging with other galaxies. Disentangling the relative contribution of these processes is essential to understand both the emergence of today’s diverse galaxy population and the cosmology in which galaxies form and evolve. In principle, the distribution of ages and metallicities of a galaxy’s stellar populations is informative about its assembly history. However, this rich information content is not yet systematically obtained for the majority of galaxies, as they are not resolved on a star-by-star basis. In this thesis, I build on a methodology that can extract age-metallicity distributions from observed integrated spectra alone. I verified that such a technique is robust by using observations of a nearby stellar system, where additionally the ages and metallicities of individually resolved stars are known. Using state-of-the-art cosmological, hydrodynamical simulations, I showed that interactions with other galaxies dictate the assembly of stars in the central few hundred parsecs of galaxies, which are thus ideal regions to study merger histories. The joint analysis of integrated spectra of galaxy centers from real and mock observations confirms the recovery of signatures in ages and metallicities reminiscent of past merger events. These promising results pave the way in measuring galaxy merger statistics from current and future spectroscopic data to understand their role in shaping galaxy properties over cosmic time.