Taking galactic archaeology beyond the near field

My proposed research programme will address two fundamental questions in astrophysics: how do galaxies evolve and what is the nature of the ubiquitous yet invisible substance known as dark matter? We know that galaxies began as tiny quantum fluctuations in the early Universe, which then expanded with inflation to produce local overdensities in dark matter. These clumps attracted gas, which condensed to form the first stars. As these stars clustered they formed galaxies. What we do not yet know, however, is how these early featureless groups metamorphosed into the diverse range of morphologies that can be observed today. Galaxies in our night sky contain anything from a hundred million to a hundred trillion stars and whilst many are elliptical, or spheroidal in shape, others are more exotic; like our Milky Way, which resembles a pancake with spiral arms. The evolution of galaxies has a number of drivers acting on different scales. The interstellar scale includes processes such as star formation, explosions of massive stars, and interactions between stars. On a larger scale, mergers between nearby galaxies serve to reshape the distribution of stars as well as deposit alien stars from satellite galaxies in the outer haloes. The haloes of dark matter that enshroud all galaxies modulate the rate of star formation and merger events. We need to reveal the detailed balance between these drivers of galactic evolution to explain the origin of the present diversity. The emerging field of 'galactic archaeology' offers an extremely promising path to answering these questions. It relies on the concept of 'descent with modification' in evolutionary biology, which describes the passing down of traits between generations. All stars fuse new elements in their cores. The most massive stars live short lives, perishing in cataclysmic explosions that expel these elements into the surrounding gas. The gas condenses to form the next generation of stars. Thus, the chemical patterns of stars function as 'stellar DNA', betraying the state of chemical enrichment of the gas at the time and place of birth. Furthermore, the positions and velocities of stars indicate their orbits, which in turn reflect the distribution of dark matter in the galaxy. Thanks to the unprecedented success of recent surveys there has been a revolution in the stellar data available for the Milky Way and other nearby galaxies. I will establish a new research field, carrying out detailed galactic archaeology studies of the Milky Way and extending these to a large number of nearby galaxies. My interdisciplinary background in astrophysics and engineering will uniquely enable me to integrate advanced statistical tools with new state-of-the-art galaxy models, thus enabling me to fit a plethora of data, whilst tackling calibration issues. These tools will have far-reaching implications throughout a number of fields, including astrophysics, engineering, and health sciences, where I have already generated notable impact. My models will describe the distribution of dark matter throughout these galaxies and unlock the role played by star formation, chemical enrichment, interactions between stars, and mergers with nearby galaxies. This will place new and exciting limits on our field’s remaining unknowns such as the size of the Universe's smallest galaxies. The project will thus address central questions of astrophysics, whilst in parallel feeding back into the Big Data revolution back on Earth.