[1] Ehime Univ, Dept Phys, 2-5 Bunkyocho, Matsuyama, Ehime 7908577, Japan
[2] Chuo Univ, Dept Phys, Fac Sci & Engn, Bunkyo Ku, 1-13-27 Kasuga, Tokyo 1128551, Japan
[3] Nihon Univ, Dept Phys, Chiyoda Ku, 1-8-14 Kanda Surugadai, Tokyo 1018308, Japan
[4] RIKEN, High Energy Astrophys Lab, 2-1 Hirosawa, Wako, Saitama 3510198, Japan
[5] Kyoto Univ, Dept Astron, Sakyo Ku, Kitashirakawa Oiwake Cho, Kyoto, Kyoto 6068502, Japan
[6] Tokyo Inst Technol, Dept Phys, Meguro Ku, 2-12-1 Ookayama, Tokyo 1528551, Japan
[7] Japan Aerosp Explorat Agcy JAXA, Inst Space & Astronaut Sci ISAS, Chuo Ku, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2525210, Japan
[8] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[9] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England
[10] NASA, Astrophys Sci Div, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
[11] RIKEN, Cluster Pioneering Res, 2-1 Hirosawa, Wako, Saitama 3510198, Japan
[12] Univ Maryland, Dept Astron, College Pk, MD 20742 USA
[13] NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA
[14] Tor Vergata Univ Rome, Dept Phys, Via Ric Sci 1, I-00133 Rome, Italy
[15] INAF Astron Observ Rome, Via Frascati 33, I-00078 Monte Porzio Catone, Italy