The Missing Link in Star Cluster Evolution

The currently most popular models for the dynamical evolution of star clusters predict that the power-law cluster luminosity functions (CLFs) of young star cluster systems will be transformed rapidly into the universal Gaussian CLFs of old Milky Waytype "globular" cluster systems. Here, we provide the first evidence for a turnover in the intermediate-age ~1 Gyr old CLF in the center of the nearby starburst galaxy M82, which very closely matches the universal CLFs of old Milky Way-type globular cluster systems. Thiors provides an important test of both cluster disruption theories and hierarchical galaxy formation models. It also lends strong support to the scenario that these young cluster systems may eventually evolve into old Milky Way-type globular cluster systems. M82ʹs proximity, its shortest known cluster disruption timescale of any galaxy, and its well-defined peak of cluster formation make it an ideal candidate to probe the evolution of its star cluster system to fainter luminosities, and thus lower masses, than has been possible for any galaxy before.