From ZADEH@OSSENU.ASTRO.NWU.EDU Mon Jul  7 14:50:12 1997
From: ZADEH@OSSENU.ASTRO.NWU.EDU
Date: Mon, 7 Jul 1997 13:46:43 -0500 (CDT)
To: gcnews@astro.umd.edu
Subject: RE: GCFLASH - Vol. 5, No. 8 (Jul 3, 1997)
\title{The Origin of the High-Energy Activity at the Galactic Center}

\author{Farhad Yusef-Zadeh(1), William Purcell(1),
        \& Eric Gotthelf(2)}
\address{Dept. Physics and Astronomy, 
Northwestern University, Evanston, Ill. 60208,
(2) NASA/GSFC, Greenbelt, MD 20771}




\begin{abstract}

Recent X-ray and gamma-ray observations of the Galactic center region by
the ASCA and CGRO/EGRET instruments show evidence of 2--10 keV and $>1$ GeV
continuum emission as well as 6.7 and 6.4 keV line emission from the
inner $0.2^\circ$ of the Galactic center.  This region is also known to
host a bright nonthermal radio continuum source Sgr A East and a dense
molecular cloud M--0.02--0.07 known as the 50 km s$^{-1}$ cloud.  The 
oval-shaped nonthermal Sgr A East is physically interacting with 
M--0.02--0.07 at the Galactic center. 
A comparison between the distribution of ionized,  synchrotron and neutral gas  
suggests a self-consistent interpretation of the high-energy activity at 
the Galactic center. Our preliminary analysis of the 
data suggest a   shock model of cosmic ray acceleration at
the site of the  interaction to explain the enhanced GeV 
$\gamma$-ray emission. We also address a number of issues related to the 
spatial correlation of the diffuse radio and X-ray emitting gas as well 
as to the origin of the fluorescent 6.4 and 6.7 keV emission at the Galactic 
center.
\end{abstract}