Energy equipartition in globular clusters

We present results on the dynamical evolution of globular clusters based on the development of multi-mass King-like dynamical models, compared with observational data. The theoretical description predicts dynamical processes such as energy equipartition, mass segregation, and evaporation without resorting to numerical simulations and providing a new framework to understand the interplay among the most significant processes in the dynamical evolution (Equipartion, Segregation, Evaporation, Virialization) here referred to as the ESEV puzzle. The velocity dispersion as a function of stellar mass was fitted using both theoretical predictions and the Bianchini fitting function for 8 selected globular clusters. Our comparison with HST proper motions showed that the energy equipartition is only partial in the observed clusters. The results show that high-mass stars are closer to equipartition than low-mass stars, confirming the strong correlation between equipartition and mass segregation, with more massive stars found to be more strongly segregated in the inner regions. Independent determinations of the gravitational parameter Φ0 were also obtained by fitting surface brightness profiles by a catalog of observational data, in agreement with the kinematic analysis. These results underline the central role of dynamical models in the interpretation of the internal kinematics of globular clusters and motivate the development of even more advanced physical models.