1. Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 China
2. Physics Department and Tsinghua Centre for Astrophysics, Tsinghua University, Beijing 100084, China
3. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
4. University of Chinese Academy of Sciences, Beijing 100049, China
5. Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany
6. Zentrum für Astronomie der Universität Heidelberg, ARI, Mönchhofstr. 12-14, D-69120 Heidelberg, Germany
7. Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85740 Garching, Germany