The Environment Of Galaxies And Groups Of Galaxies

Abstract

In this thesis, we employ two numerical tools - semi- analytical models and N-body plus hydrodynamical simulations of large scale structure and individual galaxies - to explore the underlying physics governing the formation and evolution of groups of galaxies, and the role of environment in generating polar structures around disk galaxies. Using phenomenological models of baryonic physics imposed upon large-scale dissipationless simulations of the Universe, semi-analytic models (SAMs) are one of the principal methods used to model large samples of model galaxies. We sought to examine the properties of groups of galaxies with a range of densities using SAMs applied specifically to the industry-standard Millennium Run; for this work, we make use of the well-known Munich and Durham models, and their descendants. We are especially interested in how group properties change as we change the linking length of our Friends- of-Friends group finder. We compare the group populations and richness in these models and compare them both with observations and high-resolution N- body simulations. This leads us to the conclusion that the Durham models produce a much larger population of compact objects than the Munich models. We also explore the group dynamics and morphology as a function of density. We compare the luminosity distributions of galaxy groups using publicly available SAMs in order to explor