The Lives and Deaths of Star Clusters near the Galactic Center

We study the evolution and observability of young, compact star clusters nearthe Galactic center, such as the Arches and Quintuplet systems. The clustersare modeled by integrating the equations of motion of all stars whileaccounting for the internal evolution of stars and binaries, as well as theeffect of the Galactic tidal field. We find that clusters within 150 pc of theGalactic center dissolve within ~55 Myr, but their projected densities dropbelow the background density in the direction of the Galactic center withinonly a few Myr, effectively making these clusters undetectable after that time.Detailed observations of the Arches cluster, taken at face value, suggest thatits mass function is unusually flat and that the cluster contains anoverabundance of stars more massive than 20 Msun. Our dynamical analysis,however, shows that the observed characteristics of the Arches cluster areconsistent with a perfectly normal initial mass function. The observedanomalies are then caused by a combination of observational selection effectsand the dynamical evolution of the cluster. We calibrate the current parametersof the Arches cluster using a normal initial mass function and conclude thatthe cluster is more massive than 40000 Msun, has a half mass radius of about0.35 pc and is located between 50 and 90 pc from the Galactic center.