Testing Fundamental Physics with Distant Star Clusters: Analysis of
  Observational Data on Palomar 14
  We use the distant outer halo globular cluster Palomar 14 as a test case for
classical vs. modified Newtonian dynamics (MOND). Previous theoretical
calculations have shown that the line-of-sight velocity dispersion predicted by
these theories can differ by up to a factor of three for such sparse, remote
clusters like Pal 14. We determine the line-of-sight velocity dispersion of
Palomar 14 by measuring radial velocities of 17 red giant cluster members
obtained using the Very Large Telescope (VLT) and Keck telescope. The systemic
velocity of Palomar 14 is (72.28+-0.12)km/s. The derived velocity dispersion of
(0.38+-0.12)km/s of the 16 definite member stars is in agreement with the
theoretical prediction for the classical Newtonian case according to Baumgardt
et al. (2005). In order to exclude the possibility that a peculiar mass
function might have influenced our measurements, we derived the cluster's main
sequence mass function down to 0.53Msolar using archival images obtained with
the Hubble Space Telescope. We found a mass function slope of 1.27+-0.44, which
is, compared to the canonical mass function, a significantly shallower slope.
The derived lower limit on the cluster's mass is higher than the theoretically
predicted mass in case of MOND. Our data are consistent with a central density
of 0.1 Msolar pc^-3. We need no dark matter in Palomar 14. If the cluster is on
a circular orbit, our spectroscopic and photometric results argue against MOND,
unless this cluster experienced significant mass loss.
