Chemical Evolution of the Milky Way and Chemical Tagging

Abstract

One of the most important unsolved mysteries of astronomy is the formation and evolution of galaxies. The Milky Way is an ideal testbed for testing our understanding of galaxy evolution, as we can directly observe individual stars and their properties, which is generally not possible in external systems. We now have unprecedented access to a chemodynamical view of a large section of the Milky Way. This thesis sheds light on galaxy evolution by linking physical processes involved in galaxy evolution with the observed age and abundances of stars, specifically the build-up of different elements over time and the chemical distribution at different locations in the Milky Way.

The standard tool for studying chemical evolution is a galactic chemical evolution (GCE) model. In this thesis, we treat the Milky Way as a collection of concentric rings representing different radii and ignore azimuthal variation in the Galaxy. We incorporate many physical processes such as gas accretion, star formation and its feedback, stellar evolution, supernova explosion, cooling of gas, and radial mixing of gas and stars into the model. We use the theoretical nucleosynthesis yields to track the production of elements from various nucleosynthesis channels, including Type Ia supernovae (SNe Ia), asymptotic giant branch (AGB) stars, and core-collapse supernovae (CCSN). The first model we build which is based on a previous model with radial mixing is capable of matching a number of observables we see in surveys. For the first time, we qualitatively replicate the chemical distribution in the solar neighbourhood and beyond simultaneously with one set of global parameters.