Evolution and Dynamics of the Milky Way using the Gaia satellite mission

With the advent of the Gaia satellite mission, we can finally study the positions, motions, ages, and metallicities of stars across a wide sector of the Milky Way galaxy in great detail. The first data releases of Gaia have already revealed an unforeseen wealth of substructure, ranging from the vertical waves and phase spiral in the Galactic disc to the vast patterns of in-plane motions created by resonances of stellar motions with the galactic bar (and potentially also spiral pattern). Our group has already used these resonant patterns to prove/measure for the first time the slow-down of the Galactic bar and to provide the first evidence for the inertial mass of dark matter absorbing the angular momentum of the bar (thus providing strong tension with modified gravity models that lack this mass).

During this PhD project, we will both see further data releases from Gaia, which will extend the range probed by this analysis, and both from the Gaia RV subset and combination with follow-up surveys obtain major datasets with added ages and stellar abundances - the latter encode the birth place and time of stars and thus allow us to reconstruct the dynamic history of the system. Within these general parameters, Kit (Christopher) will be given freedom to develop according to his own preferences. The project involves analysing the available data, improving their quality, comparing analytical models to the data, and/or creating theoretical simulations that capture the evolution of the galaxy and identify observables that discriminate between different processes, and e.g. different parametrisations for the dark matter halo. While Kit will be given the choice at any time to shift the focus, I take from our current conversation that his interests are concentrated on the theoretical parts. In this line of research, our group has (in collaboration with Heidelberg and Leicester) developed a strategy of tailored N-body simulations that allow us to run efficient low/cost galaxy simulations with realistic structure (continuous star formation) while controlling e.g. star formation histories, profiles, mergers, etc.. Kit will interpret these simulations with improved analytical models and then compare to the data. With this, he will contribute to understanding: disc heating, radial migration in disc, resonant behaviour and substructure, and address the distribution and properties of dark matter.

During the project we will ensure that Kit develops: a firm understanding of astronomy also in a wider area, a firm understanding of Galactic dynamics. Further, Kit will improve his skills in programming (based on C++ and python), will improve his skills in large-scale parallelised computing, the writing of major scientific works, presentation skills, and organising/directing his own research within the context of a larger collaboration.