Bridging the mass gap from the first stars to the first galaxies

The research aims to answer questions about galaxy formation and evolution in the early Universe, by improving state-of-the-art cosmological simulations.

Current state of the art simulations are challenged by observations of the first galaxies in the early universe, as we observe a lot more galaxies that are: massive; compact; or have an unusual chemical make-up, than expected from simulations. This project aims to answer questions relating to the formation and evolution of these early galaxies.

This will be done by running simulations with the new additions detailed below, and comparing the results to observations.

One aspect will be including radiation that can split molecular hydrogen, H2, into two hydrogen molecules. As H2 crucial in cooling gas this will change how stars and galaxies form.

Another aspect is how current simulations treat groups of stars. They deal with groups of stars of average, assuming that the group is large enough that it reproduces the statistical distribution of stellar properties (e.g. mass). However, at earlier times in the universe there are fewer stars and this assumption fails.

This project will instead randomly sample stars to build up galaxies, and analyse how this changes the properties of galaxies, and if they move closer to what is currently observed. With the simulations we will also be able to explore any other aspects of galaxy formation and evolution of interest.