Galactic Structure and History with chemodynamical models

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Within the next three years, ESA's Gaia mission will start to provide three-dimensional positions and proper motions a sample of around a billion stars, ten thousand times larger than any previous catalogue. Concurrently, large-scale spectroscopic surveys are producing detailed information on the chemical composition and ages of stars. The two surveys are complementary: the Gaia kinematics tell us about the present-day structure and dynamics of the Galaxy, while the abundance information reveals where stars were born. Oxford plays a leading role in developing the chemodynamical modelling tools used to infer the present-day structure and past history of the Galaxy from such data. Only 5 years ago we discovered that radial migration plays a key role in shaping the Galaxy: when stars experience the rotating potential of a passing spiral arm, they undergo large changes in angular momentum and Galactocentric radius, which induces much more chemical mixing in the disc than previous naive models. Yet, the quantitative effects on spiral galaxies like the Milky Way are poorly known.Naturally, this project encompasses two phases: Mostly theoretical work to improve the understanding of radial migration and disc heating in the first 1.5 years, and application of these improved models to the first Gaia data release mid-term of this PhD project.The current work plan for the student is as follows: Study of the relevant literature and background knowledge for the first three months until Jan 2016, focussing on Galactic dynamics, chemical evolution and advanced statistical methods. Also, the student will be trained in programming skills, in particular C++. After this, the student will learn to use the existing software within the group, including chemodynamic models and our advanced spectroscopic code, which will later provide inputs for the modelling. The student will work on an improved analytic understanding of the involved processes (radial migration, heating, better understanding of chemical enrichment) and explore the viability and robustness of predictions for the imminent Gaia data release. During this first period we already have an abundance of data from surveys (Apogee, Gaia-ESO, SEGUE, RAVE, GCS, etc.), which serve for training and may deliver first insights and publications. A first project will be to constrain kinematic aberrations relating to disc structure in the APOGEE, RAVE, and SEGUE surveys.In the second half we will measure Galactic parameters and detailed effects of Galactic structure on the solar neighbourhood as measured by Gaia. Depending on the level of expertise, skills and interests developed by the student during, the project scope will be tailored between more theoretical work on new ways to understand the physics of our Galaxy, and data analysis using the existing tools within the group.