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From: Shogo NISHIYAMA <shogo@kusastro.kyoto-u.ac.jp>
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%astro-ph/0809.3089
%http://www.kusastro.kyoto-u.ac.jp/~shogo/papers/08NishiyamaMagFGC.pdf

\documentstyle[apjfonts,emulateapj]{article}

\begin{document}

\title{Magnetic Field Configuration at the Galactic Center
Investigated by Wide Field Near-Infrared Polarimetry}

\author{Shogo Nishiyama\altaffilmark{1,2},
Motohide Tamura\altaffilmark{2},
Saori Kanai\altaffilmark{3},
Shuji Sato\altaffilmark{3},
Tetsuya Nagata\altaffilmark{1},
Ryo Kandori\altaffilmark{2},
Nobuhiko Kusakabe\altaffilmark{4},
James H. Hough\altaffilmark{5},
and Haruyuki Okuda\altaffilmark{7}
Kyoto 606-8502, Japan; \myemail}

Mitaka, Tokyo 181-8588, Japan}

\altaffiltext{3}{Department of Astrophysics, Nagoya University, 
Nagoya 464-8602, Japan}

\altaffiltext{4}{Department of Astronomical Sciences,
Graduate University for Advanced Studies (Sokendai),
Mitaka, Tokyo 181-8588, Japan}

\altaffiltext{5}{Centre for Astrophysics Research, University of Hertfordshire,
Hatfield, Herts AL10 9AB, UK}

\altaffiltext{6}{Graduate School of Natural Sciences, Nagoya City University,
Nagoya 467-8501, Japan}

\altaffiltext{7}{Institute of Space and Astronautical Science, 
Japan Aerospace Exploration Agency, 
Sagamihara, Kanagawa 229-8510, Japan}
%------------------------------------------------------

\begin{abstract}

We present a polarimetric map of a $20\arcmin \times 20\arcmin$ area
toward the Galactic center.
The polarization of point sources has been measured 
in the $J$, $H$, and $K_S$ bands
using the near-infrared polarimetric camera SIRPOL on the 1.4 m telescope IRSF.
One percent or better accuracy 
of polarization degree is achieved
for sources with $J<14.5$, $H<13.5$, and $K_S<12.0$.
Comparing the Stokes parameters between high extinction stars 
and relatively low extinction ones,
we have obtained a polarization originating from magnetically aligned dust grains
at the central region of our Galaxy of at most 1$-$2 kpc.
The distribution of 
the position angles shows a peak at $\sim$20\degr,
nearly parallel to the Galactic plane,
suggesting a toroidal magnetic configuration.
The derived direction of the magnetic field is in good agreement with
that obtained from far-infrared/submillimeter observations,
which detect polarized thermal emission from dust in the molecular clouds 
at the Galactic center.
Our results show that
by subtracting foreground components,
near-infrared polarimetry allows investigation of
the magnetic field structure {\it at } the Galactic center.

\end{abstract}

\keywords{Galaxy:center --- dust,extinction--- polarization --- infrared:ISM --- ISM:magnetic fields}

%------------------------------------------------------

\end{document}