Halo globular clusters observed with AAOmega: dark matter content,
  metallicity and tidal heating
  Globular clusters have proven to be essential to our understanding of many
important astrophysical phenomena. Here we analyse spectroscopic observations
of ten Halo globular clusters to determine their dark matter content, their
tidal heating by the Galactic disc and halo, describe their metallicities and
the likelihood that Newtonian dynamics explain their kinematics. We analyse a
large number of members in all clusters, allowing us to address all these
issues together, and we have included NGC 288 and M30 to overlap with previous
studies. We find that any flattening of the velocity dispersion profiles in the
outer regions of our clusters can be explained by tidal heating. We also find
that all our GCs have M/L_V < 5, therefore, we infer the observed dynamics do
not require dark matter, or a modification of gravity. We suggest that the lack
of tidal heating signatures in distant clusters indicates the Halo is not
triaxial. The isothermal rotations of each cluster are measured, with M4 and
NGC 288 exhibiting rotation at a level of 0.9 +/- 0.1 km/s and 0.25 +/- 0.15
km/s, respectively. We also indirectly measure the tidal radius of NGC 6752,
determining a more realistic figure for this cluster than current literature
values. Lastly, an unresolved and intriguing puzzle is uncovered with regard to
the cooling of the outer regions of all ten clusters.
