1. Department of Astronomy, Xiamen University, Xiamen, Fujian 361005, P. R. China
2. Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, Yangzhou, 225009, P. R. China
3. School of Information Science and Engineering, NingboTech University, Ningbo, 315100, P. R. China
4. Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata 2-4, Tokai, Ibaraki 319-1195, Japan
5. Department of Physics and Astronomy, Hubei University of Education, Wuhan 430205, P. R. China
6. School of Physics and State, Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, P. R. China
7. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, 100871, P. R. China
8. School of Physics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, P. R. China