Orbits and quantization rules in galactic potentials: a novel path to constrain dark matter/gravity models?

The dynamics of baryonic tracers (stars and star clusters) in galactic potentials depends on the underlying gravity field, which by itself is often not specific enough in terms of the microscopic dark matter (DM) properties, nor of modified gravity (MG) laws. Therefore, the ensuing impact onto baryonic mass density and velocity profiles may result in constraints of little distinctive character with respect to the underlying DM or MG models. We advocate the rich area of orbital theory as a means to derive new constraints on different classes of DM or MG models. For example, the nature of (tracer) orbits within classical vs quantum-wave DM halo potentials can differ markedly, with less chaotic orbits - if any- expected for the latter. We will present first theory results, also demonstrating how fruitful the DM problem turns out to be for the understanding of self-gravitating quantum systems, in general.