GALACTICNUCLEUS · The Fingerprint of a Galactic Nucleus: A Multi-Wavelength, High-Angular Resolution, Near-Infrared Study of the Centre of the Milky Way

Galactic stellar nuclei are very common in all types of galaxies and are marked by the presence of nuclear star clusters, the densest and most massive star clusters in the present-day Universe. Their formation is still an unresolved puzzle. The centre of the Milky Way contains a massive black hole and a stellar nucleus and is orders of magnitude closer than any comparable target. It is the only galactic nucleus and the most extreme astrophysical environment that we can examine on scales of milli-parsecs. It is therefore a crucial laboratory for studying galactic nuclei and their role in the context of galaxy evolution. Yet, suitable data that would allow us to examine the stellar component of the Galactic Centre exist for less than 1% of its projected area. Moreover, the well-explored regions are extraordinary, like the central parsec around the massive black hole, and therefore probably not representative for the overall environment. Fundamental questions on the stellar population, structure and assembly history of the Galactic Centre remain therefore unanswered. This project aims at addressing the open questions by obtaining accurate, high-angular resolution, multi-wavelength near-infrared photometry for an area of several 100 pc^2, a more than ten-fold increase compared to the current state of affairs. The Galactic Centre presents unique observational challenges because of a combination of high extinction and extreme stellar crowding. It is therefore not adequately covered by existing or upcoming imaging surveys. I present a project that is specifically tailored to overcome these observational challenges. In particular, I have developed a key technique to obtain the necessary sensitive, high-angular resolution images with a stable point spread function over large, crowded fields. It works with a range of existing ground-based instruments and will serve to complement existing data to provide a global and detailed picture of the stellar nucleus of the Milky Way.