1. Institute of Astronomy, Madingley Rd, Cambridge CB3 0HA, UK
2. Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
3. Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China
4. Heidelberger Institut für Theoretische Studien, Schloß-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany
5. Zentrum für Astronomie der Universität Heidelberg, Astronomisches Recheninstitut, Mönchhofstr. 12-14, D-69120 Heidelberg, Germany
6. Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, Germany