ASCA Discovery of Diffuse 6.4 keV Emission Near the Sgr C Complex: A New X-ray Reflection Nebula

Hiroshi Murakami(1,4), Katsuji Koyama(1,5), Masahiro Tsujimoto(1,4), Yoshitomo Maeda(2), Masaaki Sakano(3)

(1) Department of Physics, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;,,
(2) Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802-6305, U.S.A.;
(3) Space Utilization Research Program, National Space Development Agency of Japan, 2-1-1, Sengen, Tsukuba, Ibaraki, 305-8505, Japan;
(4) Research Fellow of the Japan Society for the Promotion of Science (JSPS)
(5) CREST, Japan Science and Technology Corporation (JST), 4-1-8 Honmachi, Kawaguchi, Saitama, 332-0012, Japan

Paper: ApJ, 550, 297 (2001)

EPrint Server: astro-ph/0012310


We present an ASCA discovery of diffuse hard X-ray emission from the Sgr C complex with its peak in the vicinity of the molecular cloud core. The X-ray spectrum is characterized by a strong 6.4-keV line and large absorption. These properties suggest that Sgr C is a new X-ray reflection nebula which emits fluorescent and scattered X-rays via irradiation from an external X-ray source. We found no adequately bright source in the immediate Sgr C vicinity to fully account for the fluorescence. The irradiating source may be the Galactic nucleus Sgr A^*, which was brighter in the past than it is now as is suggested from observations of the first X-ray reflection nebula Sgr B2.

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