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Globular clusters are an excellent laboratory for stellar population anddynamical research. Recent studies have shown that these stellar systems arenot as simple as previously assumed. With multiple stellar populations as wellas outer rotation and mass segregation they turn out to exhibit highcomplexity. This includes intermediate-mass black holes which are proposed tosit at the centers of some massive globular clusters. Today's high angularresolution ground based spectrographs allow velocity-dispersion measurements ata spatial resolution comparable to the radius of influence for plausible IMBHmasses, and to detect changes in the inner velocity-dispersion profile.Together with high quality photometric data from HST, it is possible toconstrain black-hole masses by their kinematic signatures. We determine thecentral velocity-dispersion profile of the globular cluster NGC 2808 usingVLT/FLAMES spectroscopy. In combination with HST/ACS data our goal is to probewhether this massive cluster hosts an intermediate-mass black hole at itscenter and constrain the cluster mass to light ratio as well as its total mass.We derive a velocity-dispersion profile from integral field spectroscopy in thecenter and Fabry Perot data for larger radii. High resolution HST data are usedto obtain the surface brightness profile. Together, these data sets arecompared to dynamical models with varying parameters such as mass to lightratio profiles and black-hole masses. Using analytical Jeans models incombination with variable M/L profiles from N-body simulations we find that thebest fit model is a no black hole solution. After applying various Monte Carlosimulations to estimate the uncertainties, we derive an upper limit of the backhole mass of M_BH < 1 x 10^4 M_SUN (with 95 % confidence limits) and a globalmass-to-light ratio of M/L_V = (2.1 +- 0.2) M_SUN/L_SUN.

Central kinematics of the globular cluster NGC 2808: Upper limit on the mass of an intermediate-mass black hole