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 gcnews.tex International Journal of Modern Physics D,  June
 2009, Vol. 18 Issue 6, p889
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%astro-ph/0808.2624
%\documentclass[draft]{ws-ijmpd}
\documentclass{ws-ijmpd}

\begin{document}

\markboth{Mark J. Reid}
{}

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\catchline{}{}{}{}{}
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\title {IS THERE A SUPERMASSIVE BLACK HOLE\\
AT THE CENTER OF THE MILKY WAY?}

%\runninghead{Supermassive Black Hole}

\author{Mark J. Reid}

\address{Harvard--Smithsonian Center for Astrophysics\\
          60 Garden Street, Cambridge, MA 02138, USA\\
          mreid@cfa.harvard.edu}


%% manuscript produces a one-column, double-spaced document:
% \documentclass[manuscript]{aastex}
%% preprint2 produces a double-column, single-spaced document:
% \documentclass[preprint2]{aastex}

\def\Rsch           {\ifmmode {R_{\rm Sch}} \else  {$R_{\rm Sch}$} \fi}
\def\MoverR         {\ifmmode {M/R} \else  {$M/R$} \fi}
\def\Mh             {\ifmmode {M_h} \else  {$M_h$} \fi}
\def\rhoh           {\ifmmode {\rho_h} \else  {$rho_h$} \fi}
\def\Msun           {M$_\odot$}
\def\Msunpercpc     {M$_\odot$~pc$^{-3}$}
\def\kms            {km~s$^{-1}$}
\def\etal           {et al.}
\def\ie             {i.e.}
\def\eg             {e.g.}
\def\NeII           {Ne~{\small II}}
\def\um             {$\mu$m}
\def\SgrA           {Sgr~A*}
\def\SgrAwest       {Sgr~A-West}
\def\SgrAeast       {Sgr~A-East}
\def\p              {\phantom{>}}
\def\q              {\phantom{0}}

\maketitle

\begin{history}
\received{2008 August 18}
\revised{}
\comby{Managing Editor}
\end{history}

\begin{abstract}
This review outlines the observations that now
provide an overwhelming scientific case that the center of our
Milky Way Galaxy harbors a supermassive black hole.
Observations at infrared wavelength trace stars that
orbit about a common focal position and require a central mass ($M$)
of $4\times10^6$~\Msun\ within a radius of 100~AU.  Orbital
speeds have been observed to exceed 5,000~\kms.  At the
focal position there is an extremely compact radio source (\SgrA),
whose apparent size is near the Schwarzschild radius ($2GM/c^2$).
This radio source is motionless at the $\sim1$~\kms\ level at the
dynamical center of the Galaxy.  The mass density required by these
observations is now approaching the ultimate limit of a supermassive
black hole within the last stable orbit for matter near the event horizon.

\end{abstract}

\end{document}



-------------------------------------------------------------
Mark J. Reid                 Phone: 617-495-7470
Harvard-Smithsonian CfA      Fax  : 617-495-7345
60 Garden Street             Email: reid@cfa.harvard.edu
Cambridge, MA 02138, USA     Web  : www.cfa.harvard.edu/~reid
-------------------------------------------------------------