I researched for my PhD in relativistic cosmology, supervised by George Ellis at Cambridge, where I also worked with Stephen Hawking. After positions at University College London and the Institute for Theoretical Physics in Hamburg, I became a lecturer in theoretical astrophysics at the University of Leicester, and was promoted to a readership and then a personal chair in 1992.
I have held long-term visiting positions at the Observatoire de Paris and currently at the Astronomical Institute of the University of Amsterdam, and am Visiting Professor at Leiden University. I am Deputy Editor-in-Chief of Monthly Notices of the Royal Astronomical Society, one of the world's leading astronomy journals.
I was awarded a Senior Fellowship of the Particle Physics and Astronomy Research Council in 1995, and a Gauss Professorship of the Goettingen Academy of Sciences in 1997. In 2002, I received a Royal Society Wolfson Research Merit Award, and in 2014 the Eddington Medal of the Royal Astronomical Society for investigations of outstanding merit in theoretical astrophysics.
My research centres on astrophysical accretion, particularly on to black holes. This process uses gravity to release energy from matter in the most efficient way possible on large scales, and so powers the brightest objects in the universe. These include X-ray binaries, ultraluminous X-ray sources and gamma-ray bursters.
Almost every galaxy has a supermassive black hole at its centre, and this has strongly affected its growth and evolution. I have been closely involved in understanding how this can occur, and in turn how the black hole gains mass and grows along with the galaxy. In following these interests, I have worked extensively on accretion disc structure, binary stellar evolution and galaxy evolution.