========================================================================

                              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
========================================================================
Vol. 9, No. 14                                              Feb 2, 1999


Recently submitted papers:
--------------------------

Email    : paolo@soyouz.saclay.cea.fr
Title    : Deep SIGMA observations of the central square degree of the 
           Galaxy
Author(s): P. Goldoni^1, A. Goldwurm^1, F. Lebrun^1, J. Paul^1,   J.-P. 
           Roques^2,E. Jourdain^2,L. Bouchet^2,P. 
           Mandrou^2,E.Churazov^3,4,M. Gilfanov^3,4, R.   
           Sunyaev^3,4,A.Dyachkov^3, N. Khavenson^3,K. 
           Sukhanov^3,I.Tserenin^3, N. Kuleshova^3
Institute: (1)  DAPNIA/Service d'Astrophysique, CEA/Saclay, F-91191 
           Gif-Sur-Yvette, France   (2)  Centre d'Etude Spatiale des 
           Rayonnements, 9 Avenue du Colonel Roche, BP 4346, 31029 
           Toulouse Cedex France   (3)  Space Research Institute, 
           Profsouznaya 84/32, Moscow 117810, Russia   
           (4)  Max-Planck-Institut fuer Astrophysik, 
           Karl-Schwarzschild-Str. 1,85740 Garching   bei Munchen, 
           Germany
Paper    : To appear in the Proceedings of the 3rd INTEGRAL workshop
EPrint   : astro-ph/9901392

Abstract:
The Center of the Milky Way emits radiation through all the
electromagnetic spectrum due to the presence of several astrophysical
phenomena.  Various scientifical questions remain unsolved in the
picture that emerge from observations, the main one being the presence
and activity of a supermassive black hole at the Galactic Center.
Also in the X-ray band a strong diffuse emission is detected up to 22
keV, it has been suggested that its origin is linked to past high
energy activity of the Galactic Center.  The French SIGMA soft gamma
ray telescope on board the Russian Granat satellite observed the
Galactic Center (GC) for about 9 * 10^6 seconds from 1990 to the end
of 1997. Its unique imaging capabilities coupled with the
unprecedented exposure already allowed us to set preliminary
constraints on the persistent high energy emission from Sgr A*.  Here
we present a new analysis of the complete set of observations of this
region taking into account the possible presence of diffuse emission
in the low energy channels. This allows us both to test current
advection models of high energy emission from SgrA* and to investigate
on past high energy activity.
------------------------------------------------------------------------


(Older versions of the Newsflash can be found at the gcnews web-page)
========================================================================
			       Edited by
Angela Cotera                                Heino Falcke
(cotera@ipac.caltech.edu)                    (hfalcke@mpifr-bonn.mpg.de)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 For Abstract submission please send the (La)Tex file of your paper to
                          gcnews@mpifr-bonn.mpg.de
========================================================================