A family of potential--density pairs has been found for spherical halos 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 generating initial conditions for
spherical galaxy simulations.Comment: Paper accepted for publication in MNRAS, with four figure
