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                              G C N E W S
                             * Newsflash *

            - The Newsletter for Galactic Center Research -

gcnews@mpifr-bonn.mpg.de             http://www.mpifr-bonn.mpg.de/gcnews
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Vol. 10, No. 13                                              Aug 31, 1999

Dear subscriber:

The table of contents for the Galactic Center proceedings "The Central
Parsecs of the Galaxy", eds. H. Falcke, A. Cotera, W. Duschl,
F. Melia, M. Rieke, ASP Conf. Series, Vol. 186 are available for some
time now on our home page. This will be of help if you want to have a 
complete reference with page numbers.


Recently submitted papers:
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Email    : hiro@cr.scphys.kyoto-u.ac.jp
Title    : ASCA Observations of the Sgr B2 Cloud: An X-Ray Reflection  
             Nebula
Author(s): Hiroshi Murakami(1,3),   Katsuji Koyama(1,4), Masaaki 
           Sakano(1,3), and   Masahiro Tsujimoto(1)    Yoshitomo 
           Maeda(2,3)
Institute: (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) Research Fellow of the Japan 
           Society for the Promotion    of Science (JSPS)   (4) CREST, 
           Japan Science and Technology Corporation   (JST), 4-1-8 
           Honmachi, Kawaguchi, Saitama, 332-0012, Japan
Paper    : accepted in ApJ
EPrint   : astro-ph/9908229

Abstract:
We present the ASCA results of imaging spectroscopy of the giant 
molecular cloud Sgr B2. The X-ray spectrum is found to be very 
peculiar; it exhibits a strong emission line at 6.4 keV, a low energy 
cutoff below about 4 keV and a pronounced edge-structure at 7.1 keV. The 
X-ray image is extended and its peak position is shifted from the core 
of the molecular cloud toward the Galactic center by about 1-2 
arcminute. The X-ray spectrum and the morphology are well reproduced 
by a scenario that X-rays from an external source located in the 
Galactic center direction are scattered by the molecular cloud Sgr B2, 
and come into our line of sight. Thus Sgr B2 may be called an 
X-ray reflection nebula. Possible implications of the Galactic center 
activity related to this unique source are presented.
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			       Edited by
Angela Cotera                                Heino Falcke
(cotera@ipac.caltech.edu)                    (hfalcke@mpifr-bonn.mpg.de)
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