The Gravitational Suppression Hypothesis: Dynamical Analysis in the Small Velocity Regime

In a previous paper we have proposed a non–Newtonian, phenomenological description of the effective gravitational force acting between exotic dark matter and baryons, which was shown to fit well the kinematics in the inner regions of low surface brightness, gas–rich galaxies. The Gravitational Suppression (GraS) scheme is, admittedly, an ad-hoc model; it does however successfully address interesting cosmological issues. Here, we test the potential generality of the GraS concept. GraS predictions on motions on scales measurable in dwarf spheroidal galaxies and in the solar neighborhood show significant departures from those of Newtonian mechanics. By analyzing such systems, we find that the paradigm of a universal GraS potential cannot be rejected. Indeed, compared to Newtonian predictions, GraS provides a better description of data, when realistic dark matter density profiles are considered. Subject headings: Cosmology: dark matter — Galaxies: dwarf — Galaxies: halos — Galaxy: solar neighborhood — Gravitation — Stellar dynamics