1. Department of Astronomy, Tsinghua University , Beijing 100084, China
2. Department of Astrophysical Sciences, Peyton Hall, Princeton University , Princeton, NJ 08540, USA
3. Department of Astronomy and Astrophysics, University of California . Santa Cruz, 1156 High St, Santa Cruz, CA 95064, USA
4. Argonne National Laboratory , Argonne, IL 60439, USA
5. Department of Astronomy and Steward Observatory, University of Arizona , Tucson, AZ 85721, USA
6. Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University , CA 94305, USA
7. Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 93720, USA
8. Department of Statistical Sciences, University of Toronto , Toronto, M5S 3G3, Canada
9. David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , Toronto, M5S 3H4, Canada
10. Dunlap Institute for Astronomy & Astrophysics, University of Toronto , Toronto, M5S 3H4, Canada