Log core density of the R06 GCs (estimated from central surface brightness) as a function of dynamical age. Filled circles are high-concentration GCs which have been assigned c = 2.5 in Harris (1996). The surface-brightness profiles of these GCs show a central cusp, and they are often termed collapsed-core even though the link between cuspy profiles and dynamically collapsed cores is uncertain. Density estimated from surface brightness does actually show a mild peak at a dynamical age of about 15–20 (solid smoothing line), but does not follow a pattern as distinctive as that of the overall density obtained from simulations, and the presence of a central cusp is not a guarantee of old dynamical age.