Galactic Archaeology with Resolved Stellar Populations in the Local Group: From Building Blocks to Oblivion

Abstract

A typical galaxy goes through three main stages during its life. In this thesis I present a series of articles published in international peer reviewed astronomical journals over the candidature, which together investigate each of the three stages. In the beginning, a galaxy is a pristine building block – undisturbed. It is likely to spend billions of years in this stage, even once it has been captured by a larger host galaxy to eventually be accreted and dispersed. I study the nearby dwarf spheroidal galaxies Carina and Fornax to gain a greater understanding of their structural properties, and to investigate signs of significant disruption. The next major stage is accretion. This is the process by which a galaxy is absorbed into a larger host, gradually torn apart either over millions or billions of years. I characterise key substructures of the M31 stellar halo, and develop novel techniques for measuring their properties in the presence of significant contamination. The final stage is oblivion. Once the process of accretion is complete, the accreted galaxy is completely mixed through the host, largely lying in the stellar halo of its new home. Galactic stellar halos are expected to be principally made up of such accretions. I study the stellar halo of M33, and investigate the limits of what can be determined from the presently available data.