Can elliptical galaxies be equilibrium systems?

The paper examines whether elliptical galaxies can be considered equilibrium systems in which the gravitational and centrifugal potential is constant on the external surface. It is found that such equilibrium models as Emden-Chadrasekhar polytropes and Roche polytropes with n equals 0 can account for the majority of the observations relative to the ratio of maximum rotational velocity to central velocity dispersion in elliptical systems. Models that are a good fit to the observed data are characterized by an inner component (where most of the mass is concentrated) and a low-density outer component. It is concluded that spheroidal oblate models describing elliptical galaxies cannot be ruled out until new analyses relative to more refined theoretical equilibrium models (involving, for example, massive halos) and more detailed observations are performed.