Thursday

I will describe the predictions of a simple semi-empirical model for the impact of stellar clustering on the structural evolution of galaxies based on their position on the stellar-mass halo-mass (SMHM) relation. Anchored on empirical galaxy scaling relations, halo abundance matching, dynamical constraints, and numerical simulations, the model predicts the star formation environment at the epoch of halo collapse, and its impact on GC formation. Galaxies that form earlier host larger more GCs, leading to more energetic galactic outflows due to spatially and temporally clustered SNe. UDGs emerge naturally in this context through heating of the stellar orbits in galaxies with rich GC systems. The model provides a good fit to the constraints on the stellar and DM mass distribution of group (e.g. DF2/DF4) as well as gas-rich field UDGs that appear to be DM-deficient. The location of galaxies in the SMHM plane also explains the diversity of mass-to-light ratios found across the population of field galaxies. We conclude that stellar clustering is an essential ingredient of galaxy evolution and should be included in galaxy formation models and simulations.