Star formation at the Galactic Centre: Coevolution of multiple young stellar discs

Abstract

Studies of the Galactic Centre suggest that in situ star formation may have given rise to the observed stellar population near the central supermassive black hole (SMBH). Direct evidence for a recent starburst is provided by the currently observed young stellar disc (2–7 Myr) in the central 0.5 pc of the Galaxy. This result suggests that star formation in galactic nuclei may occur close to the SMBH and produce initially flattened stellar discs. Here, we explore the possible build-up and evolution of nuclear stellar clusters near SMBHs through in situ star formation producing stellar discs similar to those observed in the Galactic Centre and other nuclei. We use N-body simulations to model the evolution of multiple young stellar discs and explore the potential observable signatures imprinted by such processes. Each of the five simulated discs is evolved for 100 Myr before the next one is introduced in the system. We find that populations born at different epochs show different morphologies and kinematics. Older and presumably more metal-poor populations are more relaxed and extended, while younger populations show a larger amount of rotation and flattening. We conclude that star formation in central discs can reproduce the observed properties of multiple stellar populations in galactic nuclei differing in age, metallicity, and kinematic properties.