Lecture to grad students: Modelling Galaxies

Spectacular increases in the quality of data available for our Galaxy (Gaia, APOGEE, LAMOST, Galah, WEAVE...) and for external galaxies (MUSE, MANGA, SAMI,...) demands a quantum step in the sophistication of the galaxy models used to extract science from data. What's now essential are models in which several distinct populations coexist in dynamical equilibrium in a common self-consistent gravitational field. In a basic model of our Galaxy the components are (i) subpopulations of the thin and the thick discs that are characterised by age and position in the (alpha,Fe) plane; (ii) halo stars, (iii) metal-poor & metal-rich globular clusters, (iv) dark matter. I will explain how new technology associated with the use of angle-action coordinates now enables us to make such models. If time allows I will sketch the exciting prospects for using perturbation theory to model the dynamical response of such a model.