Modeling Star Clusters Across Cosmic Time

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The approximately 150 Globular star clusters (GCs) of the Milky Way are among the oldest objects in our Galaxy. Many galaxies in the Local Group have GCs, and they have been detected around massive galaxies like M87. Recent deep observations show GCs at high redshifts. Computer simulations of structure formation in the universe begin to resolve GC scales; future instruments and better simulations will soon provide a census of properties of GCs out to cosmological distances. Main dynamical processes in GCs such as internal relaxation, stellar evolution, dynamics of few-body encounters, tidal fields are understood in principle, but a comprehensive picture of GC evolution is still missing. High performance computing using accelerators (GPU) and direct N-body simulation allows for the first time to do a larger sample of complete simulations of these enigmaic objects including real star number and all astrophysical effects. Our models will be done in close coordination and mutual checking with Monte Carlo (MOCCA) models - they allow a much larger survey sample, but provide less details and less accurate models of the history of all individual objects in the star cluster. GCs emit gravitational radiation from merging black holes and neutron stars; our models will constrain the parameters of gravitational wave sources in GCs. Furthermore some fiducial models of Galactic globular clusters are planned which can be compared with high resolution spectrophotometric observations, obtained with the MUSE instrument at the Very Large Telescope (VLT) of the European Southern Observatory (ESO) by our observational collaborators.