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 ms.tex ApJL, 2006 in press
Date: Wed, 29 Mar 2006 19:59:53 +0800
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%astro-ph/0603683
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%\slugcomment{Submitted to The Astrophysical Journal}
\shorttitle{Testing RIAF model for Sgr A*}
\shortauthors{Yuan et al.}
%\received{}
%\received{2003 December 30}
\begin{document}
%\date{}

\title{Testing RIAF model for Sgr A* using the size measurements}

\author{Feng Yuan\altaffilmark{1,2}, Zhi-Qiang Shen\altaffilmark{1,2}
and Lei Huang\altaffilmark{1,3}}
\altaffiltext{1}{Shanghai Astronomical Observatory, Chinese Academy of
Sciences, 80 Nandan Road, Shanghai 200030, 
China;fyuan,zshen,muduri@shao.ac.cn}
\altaffiltext{2}{Joint Institute for Galaxy and Cosmology (JOINGC) of SHAO
and USTC}
\altaffiltext{3}{Graduate School of Chinese Academy of Sciences, Beijing 
100039,
China}

\begin{abstract}

Recent radio observations by the VLBA at 7 and 3.5 mm produced the
high-resolution images of the compact radio source located at the
center of our Galaxy---Sgr A*, and detected its
wavelength-dependent intrinsic sizes at the two wavelengths. This
provides us with a good chance of testing previously-proposed
theoretical models for Sgr A*. In this {\em Letter},
we calculate the size based on the radiatively inefficient
accretion flow (RIAF) model proposed by Yuan, Quataert \& Narayan
(2003). We find that the predicted sizes after taking into account
the scattering of the interstellar electrons are
consistent with the observations. We further predict an image of
Sgr A* at 1.3 mm which can be tested by future observations.

\end{abstract}

\keywords{accretion, accretion disks --- black hole physics ---
galaxies: active --- Galaxy: center ---
radiation mechanisms: non-thermal}

---------------------------------
Feng Yuan
Shanghai Astronomical Observatory
80 Nandan Road, Shanghai 200030, China
Tel: 86-21-64386191 ext 261
http://www.shao.ac.cn/fyuan
---------------------------------