1. McWilliams Center for Cosmology, Carnegie Mellon University , Pittsburgh, 15213 PA, USA
2. Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México , Apdo. Postal 72-3, 58089 Morelia, Mexico
3. Jülich Supercomputing Centre , Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, D-52425 Jülich, Germany
4. Department of Physics and Astronomy ‘Augusto Righi,’ University of Bologna , via Gobetti 93/2, I-40129 Bologna, Italy
5. Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
6. Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA