Our Galaxy in motion: Ripples, ridges and spirals in the Milky Way

Our position within the Milky Way and the advent of several cutting-edge Milky Way surveys, e.g. Gaia, SDSS, WEAVE, 4MOST provides us a unique laboratory for studying galactic dynamics and chemistry "up close" in six dimensions, and on the scale of individual stars.

One of the most important discoveries from the Gaia mission has been to highlight significant departures from equilibrium in the Milky Way. Most traditional modelling techniques rely on assumptions of symmetry and/or that the system is in equilibrium, neither of which are the case, and it is important for us to build new modelling methods and new data analysis techniques to fully exploit the next generation of Galactic survey data.

I have designed my research program to sit at the intersection of observation, simulation and dynamical theory, to answer four fundamental questions about Galactic dynamics and evolution: How does Galactic structure form and evolve? What is the chemodynamical structure of our Galaxy? What is the distribution of dark matter in our Galaxy?

How do non-equilibrium processes shape disc galaxy evolution?

High resolution N-body models naturally capture such non-equilibrium dynamics, but there are two primary challenges: 1) it is difficult to tailor such a model to a specific system such as the Milky Way, and 2) it is challenging to fully understand the rich dynamical processes which occur within such models over the span of several Gyr.

Thus, to answer 1) I have developed an original galaxy simulation code, PRIMAL, which I have shown can tailor an existing N-body galaxy simulation to match observational data with the quality and coverage of Gaia's fourth data release. As an ERF I will develop and apply PRIMAL to DR4 (which will be released during the period of the ERF) to produce a fully self-consistent and data driven chemodynamical model of the Milky Way.

To answer 2) I am co-I within the 'Beyond BFE' collaboration, whose goal is to leverage Basis Function Expansion (BFE) to model and quantify the time evolution of disequilibrium galactic dynamics. I will produce a suite of high-resolution Milky Way-like simulations and we will use BFE to recover a functional representation of the evolving galaxies (without assumption of a parametric model).

I will quantify the formation and evolution of bars, spiral arms and the interaction of the galactic disc and halo.

Finally, I will combine PRIMAL and BFE to directly constrain the Milky Way's dark matter halo shape and density profile. I will use the M2M machinery within PRIMAL to constrain the basis function coefficients to produce the dark matter halo profile which best fits Milky Way observables, namely the stellar kinematics, stellar streams, and H1 rotation curve information.

In summary, I will create the next chemodynamical model of the Milky Way from data from Gaia and complementary ground based surveys. I will also pioneer techniques to fully understand and quantify dynamical evolution in such large particle based simulations.

With the support of an ERF and the University of Surrey, I will unveil the links between galactic structure, kinematics and chemistry. Combining this with models of current and past interactions between the Milky Way and its satellites, and confronting them with cutting edge data sets, I will discover how the Milky Way formed and evolved, furthering our understanding of the Galaxy we live in, and the wider universe.