SCYON Abstract

Received on February 22 2003

A Dynamical Model for the Globular Cluster G1

AuthorsHolger Baumgardt(1), Junichiro Makino(1), Piet Hut(2), Steve McMillan(3), Simon Portegies Zwart(4)
Affiliation(1) University of Tokyo,
(2) IAS, Princeton,
(3) Drexel University, Philadelphia,
(4) University of Amsterdam
Submitted toAstrophysical Journal


We present a comparison between the observational data on the kinematical structure of G1 in M31, obtained with the Hubble WFPC2 and STIS instruments, and the results of dynamical simulations carried out using the special-purpose computer GRAPE-6. We have obtained good fits for models starting with single cluster King-model initial conditions and even better fits when starting our simulations with a dynamically constructed merger remnant of two star clusters. In the latter case, the results from our simulations are in excellent agreement with the observed profiles of luminosity, velocity dispersion, rotation, and ellipticity. We obtain a mass-to-light ratio of M/L = 4.0 ± 0.4 and a total cluster mass of M = (8 ± 1) x 10^6 Mo. Given that our dynamical model can fit all available observational data very well, there seems to be no need to invoke the presence of an intermediate-mass black hole in the center of G1.