High resolution simulations of galactic cannibalism

Throughout this dissertation, we will use numerical simulations to probe our understanding of Hierarchical Clustering within the local Universe. We make use of the chemodynamical simulation code GCD+, to simulate several high-resolution cosmological and galactic scale simulations. We describe a suite of analysis software used to transform the simulation data into the observer’s plane, and apply it on a set of simulations that probe nearby objects being cannibalised by our own Milky Way Galaxy. We first apply our codes to the interacting Magellanic and Milky Way system, to show that the Magellanic Stream is the result of the Magellanic Clouds being torn apart by the tidal forces between them and the Milky Way. To do this, we find the set of parameters that determine a best-fit model to the observed stream, and highlight how these parameters affect the final model. We find in particular, that the disc of the Small Magellanic Cloud is required to be larger than previous studies have shown, and we cast doubt on some recent measurements of the mass of the Large Magellanic Cloud. We also make the successful prediction of distances to some of the clouds in the stream, and several bifurcations in the stream that had not been observed prior to this work. Applying our codes to cosmological scenarios, we find we are able to explain the existence of High Velocity Clouds as a natural byproduct of Hierarchical Clustering within the Λ–dominated Cold Dark Matter (ΛCDM) paradigm. We are able to produce sufficient quantities of Hi gas in such High Velocity Clouds, reflecting the known spatial and kinematical distributions of those observed, and go some of the way to reproducing other gas concentrations as well. We are able to make predictions as to their distances, placing them in the halo of the Milky Way, that are consistent also with the limited observational information thus far available.