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; hiro@cr.scphys.kyoto-u.ac.jp, koyama@cr.scphys.kyoto-u.ac.jp, tsujimot@cr.scphys.kyoto-u.ac.jp
(2) Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802-6305, U.S.A.; maeda@astro.psu.edu
(3) Space Utilization Research Program, National Space Development Agency of Japan, 2-1-1, Sengen, Tsukuba, Ibaraki, 305-8505, Japan; sakano.masaaki@nasda.go.jp
(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)
Abstract:
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.
Preprints available from the authors at hiro@cr.scphys.kyoto-u.ac.jp
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