The BANG Survey: Bulge Assembly in Nearby Galaxies

The centres of disc galaxies hold evidence of the processes that shaped them. While disruptive events such as mergers can build dispersion-dominated classical bulges, bar-driven, secular evolution often triggers the formation of rotation-dominated nuclear discs. Therefore, the frequency and stellar mass distribution of these components can constrain the relative importance of internal and external evolution in disc galaxies. To date, observational results remain elusive: photometric studies are prone to large uncertainties and spectroscopic surveys either lack complete samples or spatial resolution. In this talk, we will present new results from employing state-of-the-art data from the MUSE integral-field spectrograph in a sample of 50 disc galaxies in the volume within 40 Mpc. We will present a detailed analysis combining stellar kinematics, stellar population properties and structural analysis to unambiguously determine the abundance of classical bulges and nuclear discs, and characterise their ages and chemo-dynamical properties. We find that the fraction of nuclear discs in barred galaxies is in the range between ~80% and ~90%, whereas only ~12% to ~17% of the nuclear discs are in unbarred galaxies. In addition, our initial results show that only ~17% to ~34% of the 50 galaxies do not host nuclear discs. These results will provide a basis for testing our models of galaxy formation and evolution in cosmological simulations.