Astronomy departmental seminar - Martin Rey (Oxford)


Insights into the faint and diffuse universe of galaxies


Recent advances have transformed our understanding of galaxies at the low surface brightness frontier. New imaging capabilities have unveiled a new population of ever smaller “ultra-faint” dwarf galaxies, while astrometric measurements from the GAIA mission is revealing a growing number of chemo-dynamical structures in the diffuse outskirts of our Milky Way. Such low-mass, feeble objects are highly sensitive to the physical processes that shape the cosmological growth of galaxies in our Universe, providing an ideal laboratory for testing galaxy formation models and the nature of dark matter. This same sensitivity, however, also generates extended scatter in their properties and uncertainties in model predictions, making their interpretation challenging.

I will showcase results from the new approach of “genetically modified” cosmological simulations of galaxies, allowing us to uniquely separate the role of cosmological assemblies and physical models in a galaxy’s final observables. I will show how this unique combination of abilities enables us to extract the expected diversity in the stellar and gaseous properties of the faintest galaxies in our Universe and make testable predictions for near-future photometric and radio surveys. I will then show how this approach can provide novel and original insights into the formation of our Milky Way, opening a new pathway to interpret Galactic observations and to constrain the formation of our Galaxy in a fully cosmological context.