The smallest galaxy in the Universe - new simulations of isolated dwarf galaxies in their full cosmological context

In recent work, we have performed the first high resolution simulations of isolated “dwarf irregular” galaxies. These simulations capture the effect of individual supernovae explosions over the full age of the Universe, producing remarkably realistic galaxies that give a good match to the star formation history, metal enrichment history and stellar/gas kinematics of real isolated dwarfs. However, the simulations assume idealised initial conditions and ignore the effect of ionising photons that can inhibit or shut down star formation. In this project, the student will run new simulations of isolated dwarf galaxies in their full cosmological context. The project will make use of a new photon transport model in the “RAMSES” code, and an algorithm for “genetically modifying” simulated galaxies to perform controlled numerical experiments of the effect of mergers and environment, for the first time. These simulations will determine what sets the size and mass of the smallest galaxies in the Universe, the mass scale at which “reionisation” shuts down star formation, and whether or not mergers induce scatter in the relation between stellar mass and dark matter halo mass. The student will confront these simulations with a host of new and exciting observational data for isolated dwarfs in the field, giving unique insights into the physical processes that regulate galaxy formation at its extremities.