A Multi-Mass Velocity Dispersion Model of 47 Tucanae Indicates No
  Evidence for an Intermediate Mass Black Hole
  In this paper, we analyze stellar proper motions in the core of the globular
cluster 47 Tucanae to explore the possibility of an intermediate-mass black
hole (IMBH) influence on the stellar dynamics. Our use of short-wavelength
photometry affords us an exceedingly clear view of stellar motions into the
very center of the crowded core, yielding proper motions for $>$50,000 stars in
the central 2'. We model the velocity dispersion profile of the cluster using
an isotropic Jeans model. The density distribution is taken as a central IMBH
point mass added to a combination of King templates. We individually model the
general low-mass cluster objects (main sequence/giant stars), as well as the
concentrated populations of heavy binary systems and dark stellar remnants.
Using unbinned likelihood model fitting, we find that the inclusion of the
concentrated populations in our model plays a crucial role in fitting for an
IMBH mass. The concentrated binaries and stellar-mass black holes (BHs) produce
a sufficient velocity dispersion signal in the core so as to make an IMBH
unnecessary to fit the observations. We additionally determine that a
stellar-mass BH retention fraction of $\gtrsim 8.5\%$ becomes incompatible with
our observed velocities in the core.
