Black Holes
It is widely accepted now that super-massive black holes live at the centres of elliptical galaxies and bulges. The properties of these black holes show remarkable tight correlations with global properties of the host galaxy such as the central velocity dispersion of stars or the spheroid luminosity/mass. It has been argued that this is evidence for a co-evolution of host and black hole via a self-regulated feedback mechanism within the standard hierarchical structure formation paradigm. However, many questions are still unanswered and we aim within our group to address these using different modelling techniques.    
  1.  The formation of seed black holes at high-redshift
We are interested in how the first black holes form and in how they shape the formation of the earliest galaxies.  Black holes formed from the collapse of the first stars, as well as more massive black holes formed from the direct collapse of the primordial gas, each play important roles in the chemical and dynamical evolution of the first galaxies.  The latter may be observable by future telescopes through the radiation emitted as they rapidly accrete gas, and they may grow to become the super-massive black holes observed in the low-redshift universe.  
Selected papers:
  1.  Johnson J. L., Khochfar S., et al. 2010, in prep
  1.  Jet-feedback and black hole growth in cosmological simulations
Although no general view has yet emerged about the accretion of cold or hot gas from galaxy (Kpc) scales down to AGN (pc) scales, it is clear that black holes are not only fed by their environment but also that they are able to influence or even shape it by quasar or jet activity. This may give rise to self-regulating growth of black holes and explain the observed co-evolution of black hole and bulge mass or the duty cycles of AGN activity. By including a well-resolved jet into cosmological simulations, we try to test the impact of feedback on the accretion history of black holes.