The Motion of Stars near the Galactic Center: A Comparison of the Black Hole and Fermion Ball Scenarios

Abstract

After a discussion of the properties of degenerate fermion balls, we analyze the orbits of the stars S0-1 and S0-2, which have the smallest projected distances 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 six years by Genzel et al. and Ghez et al. The free parameters of the projected orbit of a star are the unknown components of its velocity v z and distance 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 z − v z phasespace, which fits the data, is 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 could reduce this allowed phase-space and eventually rule out one of the currently acceptable scenarios. This may shed some light into the nature of the supermassive compact dark object, or dark matter in general at the center of our Galaxy.

Dark Matter and Sterile Neutrinos

“…The physics of fermion balls as a model for the dark matter distribution at galactic centers has been studied in a series of papers. [113][114][115][116][117][118][119] For realistic models an integral over a temperature distribution is required, and a boundary condition has to be used to represent the surface of the dark matter star both in real space as in momentum space. This then allows the mass of this dark matter star to increase further.…”

Degenerate sterile neutrino dark matter in the cores of galaxies

“…Here, we point out that the physics of degenerate fermion balls that obey Eq. (4) was studied in a series of papers (Bilić et al 1999;Munyaneza et al 1998Munyaneza et al , 1999Munyaneza & Viollier 2002).…”

Boson–Fermion Stars: Exploring Different Configurations

“…In case of pure boson stars, we know that the total mass of the star tends to change according to 1/m 2 b . As a first example we take: The authors of [20] have tried to show that, choosing a fermion mass of about 16 KeV (for instance, a sterile neutrino), it was possible to explain the main dynamical features of the supermassive compact dark objects, known to exist in the Galactic center and in the center of M87, with the help of what they have dubbed fermion balls, which they propose as an alternative explanation to the more usual black hole model. Better observations [28] have, however, ruled out this model, but still leaving opened the possibility of a supermassive boson star [21].…”

“…We must take into account that the mass density profile of a boson-fermion configuration, with an extended boson halo, would be different from the profile of a fermion ball. This should be reflected in the dynamics of the orbits of stars inside such a halo, exactly as there appears a difference between the fermion ball and the black hole models [20]. We are currently investigating this possibility and the results will be reported in a separate publication [29].…”