The central mass and mass-to-light profile of the Galactic globular
  cluster M15
  We analyze line-of-sight velocity and proper motion data of stars in the
Galactic globular cluster M15 using a new method to fit dynamical models to
discrete kinematic data. Our fitting method maximizes the likelihood for
individual stars and, as such, does not suffer the same loss of spatial and
velocity information incurred when spatially binning data or measuring velocity
moments. In this paper, we show that the radial variation in M15 of the
mass-to-light ratio is consistent with previous estimates and theoretical
predictions, which verifies our method. Our best-fitting axisymmetric Jeans
models do include a central dark mass of $\sim2 \pm 1\cdot 10^3M_\odot$, which
can be explained by a high concentration of stellar remnants at the cluster
center. This paper shows that, from a technical point of view and with current
computing power, spatial binning of data is no longer necessary. This not only
leads to more accurate fits, but also avoids biased mass estimates due to the
loss of resolution. Furthermore, we find that the mass concentration in M15 is
significantly higher than previously measured, and is in close agreement with
theoretical predictions for core-collapsed globular clusters without a central
intermediate-mass black hole.
