1. Institute for Astronomy & Astrophysics, National Observatory of Athens , V. Paulou & I. Metaxa, 11532, Greece
2. Centre for Extragalactic Astronomy, Department of Physics, Durham University , Durham, DH1 3LE, UK
3. School of Mathematics, Statistics and Physics, Newcastle University , Newcastle upon Tyne, NE1 7RU, UK
4. Institute for astronomy, University of Edinburgh , Royal observatory, Edinburgh EH9 3HJ, UK
5. School of Physics & Astronomy, University of Leicester , University Road, Leicester LE1 7RJ, UK
6. Max Planck Institute for Extraterrestrial Physics , Giessenbachstrasse, D-85741 Garching, Germany
7. Instituto de Física de Cantabria (CSIC – Universidad de Cantabria) , Avenida de los Castros, E-39005 Santander, Spain
8. SISSA , Via Bonomea 265, I-34136 Trieste, Italy
9. Instituto de Astrofísica de Canarias, Calle Vía Láctea, s/n , La Laguna, E-38205 Tenerife, Spain
10. Departamento de Astrofísica, Universidad de La Laguna , La Laguna, E-38206 Tenerife, Spain
11. Exzellenzcluster ORIGINS , Boltzmannstr. 2, D-85748 Garching, Germany
12. Department of Physics and Astronomy, University of Southampton , Highfield SO17 1BJ, UK