Automated Simulations of Galaxy Morphology Evolution using Deep Learning and Particle Swarm Optimisation

The formation of Hoag-type galaxies with central spheroidal galaxies and outer stellar rings has yet to be understood in astronomy. We consider that these unique objects were formed from the past interaction between elliptical galaxies and gas-rich dwarf galaxies. We have modelled this potential formation process through simulation. These numerical simulations are a means of investigating this formation hypothesis, however the parameter space to be explored for these simulations is vast. Through the application of machine learning and computational science, we implement a new two-fold method to find the best model parameters for stellar rings in the simulations. First, test particle simulations are run to find a possible range of parameters for which stellar rings can be formed around elliptical galaxies (i.e. Hoag-type galaxies). A novel combination of particle swarm optimisation and Siamese neural networks has been implemented to perform the search over the parameter space and test the level of consistency between observations and simulations for numerous models. Upon the success of this initial step, we subsequently run full chemodynamical simulations for the derived range of model parameters in order to verify the output of the test particle simulations. We successfully find parameter sets at which stellar rings can be formed from the interaction between a gas-rich dwarf galaxy and a central elliptical galaxy. This is evidence that supports our hypothesis about the formation process of Hoag-type galaxies. In addition, this suggests that our new two-fold method has been successfully implemented in this problem search-space and can be investigated further in future applications. ~