Summary

We propose to realize a N-body lab with the aim to study the evolution of dense stellar systems. The UvA N-body lab architecture will contain special purpose GRAPE hardware, which is dedicated to gravitational force calculations, attached to the Amsterdam node of the ASCI research school DAS computer, which is a cluster of general-purpose computers. In this environment we will realize highly efficient software libraries containing N-body kernels, such as the direct method, hierarchical methods , and others. The unique combination of GRAPE hardware with a cluster all owns to speedup both the 1/r calculations, by running them on GRAPE, and to speedup the remaining calculations by parallelizing them over DAS. This allows to remove e.g. known bottle-necks in hierarchical methods executing on GRAPE hardware attached to a single host computer. Together with existing intelligent batch processing tools and interactive visualization technology [24] the N-body lab will be a very powerful, generic infrastructure. We intend to study the dynamical evolution of dense stellar systems (globular clusters, galactic bulges) and to study how the many binary X-ray sources and millisecond radio pulsars, observed in the centers of globular clusters, have formed and evolved; in this formation and evolution both stellar dynamics and stellar evolution play a key role. Therefore a code that combines stellar evolution with stellar dynamics will be constructed in the N-body lab. Another main topic of study is the effect of the presence of binary stars on the evolution towards and through core collapse in globular clusters. During core collapse (a characteristic phenomenon of gravitating systems) very unusual close interactions between stars occur, the outcome of which is completely unknown.