Evidence Against Dark Matter Halos Surrounding the Globular Clusters
  MGC1 and NGC 2419
  The conjecture that the ancient globular clusters (GCs) formed at the center
of their own dark matter halos was first proposed by Peebles (1984), and has
recently been revived to explain the puzzling abundance patterns observed
within many GCs. In this paper we demonstrate that the outer stellar density
profile of isolated GCs is very sensitive to the presence of an extended dark
halo. The GCs NGC 2419, located at 90 kpc from the center of our Galaxy, and
MGC1, located at ~200 kpc from the center of M31, are ideal laboratories for
testing the scenario that GCs formed at the centers of massive dark halos.
Comparing analytic models to observations of these GCs, we conclude that these
GCs cannot be embedded within dark halos with a virial mass greater than 10^6
Msun, or, equivalently, the dark matter halo mass-to-stellar mass ratio must be
Mdm/M_*<1. If these GCs have indeed orbited within weak tidal fields throughout
their lifetimes, then these limits imply that these GCs did not form within
their own dark halos. Recent observations of an extended stellar halo in the GC
NGC 1851 are also interpreted in the context of our analytic models.
Implications of these results for the formation of GCs are briefly discussed.
