A Dynamical Model for the Globular Cluster G1

We present a comparison between the observational data on the kinematicalstructure of G1 in M31, obtained with the Hubble WFPC2 and STIS instruments,and the results of dynamical simulations carried out using the special-purposecomputer GRAPE-6. We have obtained good fits for models starting with singlecluster King-model initial conditions and even better fits when starting oursimulations with a dynamically constructed merger remnant of two star clusters.In the latter case, the results from our simulations are in excellent agreementwith the observed profiles of luminosity, velocity dispersion, rotation, andellipticity. We obtain a mass-to-light ratio of $M/L = 4.0 \pm 0.4$ and a totalcluster mass of $M=(8\pm 1)\times 10^6 M_\odot$. Given that our dynamical modelcan fit all available observational data very well, there seems to be no needto invoke the presence of an intermediate-mass black hole in the center of G1.Comment: 12 pages, 3 figures, ApJL accepted, minor change