Potential–density pairs for spherical galaxies and bulges: the influence of scalar fields

A family of potential–density pairs has been found for spherical haloes and bulges of galaxies in the Newtonian limit of scalar–tensor theories of gravity. The scalar field is described by a Klein–Gordon equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. The net gravitational force is given by two contributions: the standard Newtonian potential plus a term stemming from massive scalar fields. General solutions have been found for spherical systems. In particular, we compute potential–density pairs of spherical, galactic systems, and some other astrophysical quantities that are relevant to generate initial conditions for spherical galaxy simulations.