A Soliton Solution for the Central Dark Masses in 47- Tuc Globular
  Cluster and Implications for the Axiverse
  We offer a standing wave explanation for the rising proper motions of stars
at the center of the globular cluster 47-Tucanae, amounting to $\simeq 0.44\%$
of the total mass. We show this can be explained as a solitonic core of dark
matter composed of light bosons, $ m \geq 10^{-18} eV $, corresponding to $
\leq 0.27 pc$, as an alternative to a single black hole (BH) or a concentration
of stellar BH remnants proposed recently. This is particularly important as
having a concentrated stellar BH remnant with the above radii is very
challenging without the heavy core since the three body encounters would
prevent the BHs to be that concentrated. We propose this core develops from
dark matter captured in the deep gravitational potential of this globular
cluster as it orbits the dark halo of our galaxy. This boson may be evidence
for a second light axion, additional to a lighter boson of $10^{-22} eV$,
favored for the dominant dark matter implied by the large dark cores of dwarf
spheroidal galaxies. The identification of two such light bosonic mass scales
favors the generic string theory prediction of a wide, discrete mass spectrum
of axionic scalar fields.
