The Globular Cluster System of NGC 6822
  We present a comprehensive analysis of the globular cluster (GC) system of
the Local Group dwarf irregular galaxy NGC 6822. Our study is based on
homogeneous optical and near-IR photometry, as well as long-slit spectroscopic
observations which are used to determine new radial velocities for 6 GCs, two
of which had no previous spectroscopic information. We construct optical-near
IR colour-colour diagrams and through comparison to simple stellar population
models infer that the GCs have old ages consistent with being 9 Gyr or older,
while their metallicities are in the range between -1.6 < [Fe/H] < -0.4. We
conduct a kinematic analysis of the GC population and find tentative evidence
for weak net rotation of the GC system, in the same sense as that exhibited by
the underlying spheroid. The most likely amplitude of rotation is ~10 km/s,
approximately half the magnitude of the observed velocity dispersion. Finally,
we use the GCs to estimate the dynamical mass of NGC 6822 within 11 kpc and we
formally find it to be in the range between (3-4)10^9 Msun. This implies an
overall mass-to-light ratio in the range of ~ 30-40 and indicates that NGC 6822
is highly dark matter dominated. The mass and the corresponding mass-to-light
ratio estimates are affected by various additional systematic effects due to
limitations of the data and the model that are not necessary reflected in the
formal uncertainties.
