1. Astrophysics Research Institute, Liverpool John Moores University , 146 Brownlow Hill, Liverpool L3 5RF , UK
2. Department of Physics, Institute for Computational Cosmology, Durham University , South Road, Durham DH1 3LE , UK
3. Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena , Raúl Bitrán 1305, La Serena , Chile
4. Departamento de Astronomía, Universidad de La Serena , Av. Juan Cisternas 1200 Norte, La Serena , Chile
5. Department of Physics & Astronomy ‘Augusto Righi’, University of Bologna , via Gobetti 93/2, I-40129 Bologna , Italy
6. Max-Planck-Institut für Astrophysik , Karl-Schwarzschild-Str. 1, D-85748 Garching , Germany