Globular Clusters with Dark Matter Halos. I. Initial Relaxation

In a series of two papers, we test the primordial scenario of globularcluster formation using results of high-resolutions N-body simulations. In thisfirst paper we study the initial relaxation of a stellar core inside a livedark matter minihalo in the early universe. Our dark-matter dominated globularclusters show features which are usually attributed to the action of the tidalfield of the host galaxy. Among them are the presence of an apparent cutoff("tidal radius") or of a "break" in the outer parts of the radial surfacebrightness profile, and a flat line-of-sight velocity dispersion profile in theoutskirts of the cluster. The apparent mass-to-light ratios of our hybrid(stars + dark matter) globular clusters are very close to those of purelystellar clusters. We suggest that additional observational evidence such as thepresence of obvious tidal tails is required to rule out the presence ofsignificant amounts of dark matter in present day globular clusters.Comment: 14 pages, 9 figures. Astrophysical Journal, in pres