Understanding the central kinematics of globular clusters with simulated
  integrated-light IFU observations
  The detection of intermediate mass black holes in the centres of globular
clusters is highly controversial, as complementary observational methods often
deliver significantly different results. In order to understand these
discrepancies, we develop a procedure to simulate integral field unit (IFU)
observations of globular clusters: Simulating IFU Star Cluster Observations
(SISCO). The input of our software are realistic dynamical models of globular
clusters that are then converted in a spectral data cube. We apply SISCO to
Monte Carlo cluster simulations from Downing et al. (2010), with a realistic
number of stars and concentrations. Using independent realisations of a given
simulation we are able to quantify the stochasticity intrinsic to the problem
of observing a partially resolved stellar population with integrated-light
spectroscopy. We show that the luminosity-weighted IFU observations can be
strongly biased by the presence of a few bright stars that introduce a scatter
in the velocity dispersion measurements up to $\simeq$40% around the expected
value, preventing any sound assessment of the central kinematic and a sensible
interpretation of the presence/absence of an intermediate mass black hole.
Moreover, we illustrate that, in our mock IFU observations, the average
kinematic tracer has a mass of $\simeq$0.75 solar masses, only slightly lower
than the mass of the typical stars examined in studies of resolved
line-of-sight velocities of giant stars. Finally, in order to recover unbiased
kinematic measurements we test different masking techniques that allow us to
remove the spaxels dominated by bright stars, bringing the scatter down to a
level of only a few percent. The application of SISCO will allow to investigate
state-of-the-art simulations as realistic observations.
