Dark Matter in Elliptical Galaxies

Abstract

Photometric and kinematical data (stellar velocity dispersion) for a set of bright elliptical galaxies (NGC 3379, 4374, 4472, 4486, 4636, 7562, 7619, 7626) have been analyzed in terms of self-consistent anisotropic models (f_∞) under the assumption of constant mass-to-light ratio [1]. The results are consistent with the possibility that dark matter in these ellipticals is absent or, at least, approximately distributed like the luminous matter. However, the above mentioned kinematical data do not pose a stringent constraint, since they extend out to a fraction of R_e only. In fact, a violation of the constant M/L assumption might be required when reliable velocity dispersion data will become available on a larger radial extent or for the small number of ellipticals where kinematical information in the outer regions already exists in the form of gas rotation curves or X-ray data.