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%astro-ph/0606282
%http://ww.astro.umass.edu/~wqd/papers/arches/

\newcommand{\as}{$^{\prime\prime}$}
\newcommand{\am}{$^{\prime}$}
\newcommand{\etal}{et al.~}
\def\xs{Arches}
\def\xq{Quintuplet}
\newcommand{\mic}{$\mu$m}
\newcommand{\nh}{N$_H$}
\shortauthors{}
\shorttitle{Chandra Observation of \xs}

\begin{document}
\slugcomment{Draft version: \today}

\title{\bf The Interplay between Star Formation and the Nuclear Environment of
our Galaxy: Deep X-ray Observations of
the Galactic Center Arches and Quintuplet Clusters}

\author{Q. Daniel Wang\altaffilmark{1}, Hui Dong\altaffilmark{1}, \& Cornelia
Lang\altaffilmark{2}}
       University of Massachusetts, Amherst, MA~01003; wqd@astro.umass.edu,
City, IA 52245; cornelia-lang@uiowa.edu
}

\begin{abstract}
The Galactic center (GC) provides a unique laboratory for a
detailed examination of the interplay between massive star
formation and the nuclear environment of our Galaxy. Here, we
present an 100 ks {\sl Chandra} ACIS observation of the Arches and Quintuplet
star clusters. We
also report on a complementary mapping of the dense molecular
gas near the Arches cluster made with the Owens Valley Millimeter Array.
We present a catalog of 244 point-like X-ray sources detected in the observation.
Their number-flux relation indicates an
over-population of relatively bright X-ray sources, which
are apparently associated with the clusters. The sources in the core of the
Arches and Quintuplet clusters are most likely extreme colliding wind
massive star binaries. The diffuse X-ray emission from the core
of the Arches cluster has a spectrum showing a 6.7-keV emission line and a
surface intensity profile declining steeply with radius, indicating an
origin in a cluster wind. In the outer regions near the Arches cluster, the
overall diffuse X-ray enhancement demonstrates a bow shock morphology and is
prominent
in the Fe K$\alpha$ 6.4-keV line emission with an equivalent width
of $\sim 1.4$ keV. Much of this enhancement may result from an ongoing collision
between the cluster and the adjacent molecular cloud, which have a relative velocity
$\gtrsim 120 {\rm~km^{-1}}$.  The older and less
compact Quintuplet cluster contains much weaker X-ray sources and
diffuse emission, probably originating from low-mass stellar objects as well as
a cluster
wind.  However, the overall population of these objects, constrained by the observed
{\sl total} diffuse
X-ray luminosities, is substantially smaller than expected for both clusters, if
they have
normal Miller \& Scalo initial mass functions. This deficiency of low-mass objects
may be a manifestation of the unique star formation environment of the Galactic
center,
where high-velocity cloud-cloud and cloud-cluster collisions are frequent.
\end{abstract}