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 GCplerion.tex, ApJL, Dec 2004, in press
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%  astro-ph/0410243


\documentclass[12pt,preprint]{aastex}

%\documentclass[preprint2]{aastex}

\newcommand{\sgr}{Sgr~A$^\ast~$}
\newcommand{\rs}{$R_{\rm S}~$}
\newcommand{\dmn}{\dot{m}_{-6}}
\newcommand{\dm}{\dot{m}}

\shorttitle{Black Hole Plerion}
\shortauthors{Atoyan \& Dermer}

\received{}


\begin{document}

\title{TeV Emission from the Galactic Center 
Black-Hole Plerion }

\author{Armen Atoyan$^1$ and Charles D. Dermer$^2$} 
\affil{$^1\,$CRM, Universit\'e de Montr\'eal, C.P. 6128, 
Montr\'eal, Canada H3C 3J7;~~atoyan@crm.umontreal.ca}

\affil{$^2\,$E\,O.\,Hulburt Center for Space Research, Code 7653,
Naval Research Laboratory,\\ Washington, DC 20375-5352;~~
dermer@gamma.nrl.navy.mil}


\begin{abstract}
The HESS collaboration recently reported highly significant
detection of TeV $\gamma$-rays coincident with Sgr~A$^\ast$
\citep{HESS}.  In the context of other Galactic Center (GC)
observations, this points to the following scenario: In 
the extreme advection-dominated accretion flow (ADAF) 
regime of the GC black hole (BH), synchrotron radio/sub-mm 
emission of $\sim 100 \,\rm MeV$ electrons emanates from 
an inefficiently radiating turbulent magnetized corona 
within 20 $R_{\rm S}$ (Schwarzschild radii) of the
GCBH.  These electrons are accelerated through 
second-order Fermi processes by MHD turbulence, 
as suggested by Liu et al.\ (2004).
Closer to the innermost stable orbit of the ADAF, 
instabilities and shocks within the flow inject 
power-law electrons through first-order Fermi acceleration 
to make synchrotron X-ray flares observed with Chandra, 
XMM, and INTEGRAL. A subrelativistic MHD wind subtending a
$\sim 1\,\rm sr$ cone with power 
$\gtrsim 10^{37}\,\rm erg\,s^{-1}$ is
driven by the ADAF from the vicinity of the GCBH.   
As in pulsar powered plerions, electrons are
accelerated at the wind termination
shock, at $\gtrsim 10^{16.5}\,$cm from the GCBH,  and 
Compton-scatter the ADAF and the far infra-red (FIR) 
dust radiation 
to TeV energies. The synchrotron radiation of these
electrons forms the quiescent X-ray source resolved by
Chandra.  The radio counterpart of this TeV/X-ray plerion, 
formed when the injected electrons cool on timescales 
of $\gtrsim 10^4\,\rm yrs$,
could explain the origin of nonthermal radio emission in the
{\it pc}-scale bar of the radio nebula Sgr A West.
\end{abstract}

\keywords{acceleration of particles---black hole 
physics---Galaxy: 
center---plasmas---radiation processes: nonthermal}

\maketitle



\end{document}