Research: Cosmological Simulations

The power of cosmological simulations to trace the development of cosmic structure has grown rapidly over the past 30 years, and state-of-the-art simulations now track well over 109 particles representing dark matter and baryonic material (normal atoms) as they interact via gravity as well as heating, radiating, shocking etc.

Including all the necessary physics in simulations is difficult, since complex processes operating on astronomically small scales, such as the formation and evolution of stars, and the growth of supermassive black holes, can have an impact on the structures which develop on much larger scales.

The 100 Mpc cube simulated by the OWLS simulations, showing the large scale filamentary structure which develops by the present day.

This means that there is a very valuable two-way interaction between simulations and observational studies:

The Birmingham group collaborates closely with simulators and theorists to bring together observations and simulations in such a fruitful partnership. For example:

OWLS Groups OWLS Gas Fraction
Left - a galaxy group in the OWLS simulations. Right - the fraction of hot gas in a set of simulated groups is plotted against the mean gas temperature (hotter gas implies a more massive group) for two differemt sets of simulations. The REF model contains star formation and supernova explosions, but no supermassive black holes. The AGN model also has energy injection from Active Galactic Nuclei, which host giant black holes. The latter model provides a much better to the low gas fractions seen (black crosses) in observed groups.