Simulating Galaxy Formation
The flagship of Durham Galaxy formation simulations is the EAGLE project. It builds on two of our earlier simulations of the universe : the GIMIC simulation (carried out at the ICC, Crain et al. 2009) and OWLS (carried out in collaboration with astronomers at Leiden University, Schaye et al 2010). These simulations showed that it was possible to incorporate the main processes of galaxy formation into a computer simulations, and that it was possible to simultaneously achieve sufficient resolution to create realistic-looking galaxies and to model a sufficiently large cosmological volume that the results were representative of the universe as a whole.
The EAGLE (Evolution of Galaxies and their Environment) simulations push the ideas presented in GIMIC and OWLS to the next level. The simulations include a state-of-the art treatment of fluid dynamics and incorporate key processes such as
- metal dependent cooling
- star formation following the observed star formation law
- metal enrichment from stellar mass loss and supernovae
- black hole accretion
- feedback from supernova and black holes
These processes are implemented using the latest numerical techniques, that allow us to treat the complex multiphase structure of the ISM. Our simulations do not artificially decouple feedback particles and allow outflows from galaxies to develop as the result of the high pressures generated within them.
In the EAGLE project, great emphasis has been placed on calibrating the simulations using observational data. As a result, the simulations present a remarkably realistic virtual universe, in which the simulated galaxies match many of the observed properties of galaxies, in particular the galaxy mass function with great fidelity. We believe that the simulations are unique in the accuracy with which they describe the universe around us.
The largest of the EAGLE simulations contains 6 billion particles, requiring many months of computing time on the world largest super-computers to complete it. The dynamic range of the simulations is impressive, allowing us to resolve the sub-kpc structure of galaxies within a box that is 100 Mpc on each side. The computing resources for the project have been provided through the DiRAC and PRACE schemes.
Papers describing the EAGLE simulations and show-casing the results are currently being written up for publication. The simulations will provide an unparalleled resource for understanding how galaxies from and how the properties of galaxies are set by the balance between feedback, star formation and black hole accretion. In addition, the fidelity of the simulations will allow us to compare to observational datasets ranging from the galaxy mass function and its evolution, through star formation rates to the correlations between galaxies and quasar sight-line probes of the inter-galactic medium.