Comparison of the Black Hole and Fermion Ball Scenarios of the Galactic Center

Faustin Munyaneza1 and Raoul D. Viollier1

1 Institute of Theoretical Physics and Astrophysics, Department of Physics,
University of Cape Town, Private Bag, Rondebosch 7701, South Africa

E-mail contact: viollier@physci.uct.ac.za

astro-ph/0103466; ApJ 564, 274 (2002)

After the discussion of the properties of degenerate fermion balls, we analyze the orbits of the stars S0-1 and S0-2, which have a projected distance of 5 mpc to Sgr A*, in the supermassive black hole as well as in the fermion ball scenarios of the Galactic center. It is shown that both scenarios are consistent with the data, as measured during the last 10 years by Genzel and coworkers and by Ghez and coworkers. The free parameters of the projected orbits of the stars are the unknown components of their velocities vz and distances z to Sgr A* in 1995.4, with the z-axis being in the line of sight. We show, in the case of S0-1 and S0-2, that the vz , z phase spaces, which fit the data, are much larger for the fermion ball than for the black hole scenario. Future measurements of the positions or radial velocities of S0-1 and S0-2, which could be orbiting within such a fermion ball, may reduce this allowed phase space and eventually rule out one of the currently acceptable scenarios. This could shed some light on the nature of the supermassive compact dark object, or dark matter in general, at the center of our Galaxy.