Testing feasibility of scalar-tensor gravity by scale dependent mass and
  coupling to matter
  We investigate whether there are any cosmological evidences for a scalar
field with a mass and coupling to matter which change accordingly to the
properties of the astrophysical system it "lives in", without directly focusing
on the underlying mechanism that drives the scalar field scale-dependent
properties. We assume a Yukawa type of coupling between the field and matter
and also that the scalar field mass grows with density, in order to overcome
all gravity constraints within the solar system. We analyse three different
gravitational systems assumed as "cosmological indicators": supernovae type Ia,
low surface brightness spiral galaxies and clusters of galaxies. Results show
that: a) a quite good fit to the rotation curves of low surface brightness
galaxies only using visible stellar and gas mass components is obtained; b) a
scalar field can fairly well reproduce the matter profile in clusters of
galaxies, estimated by X-ray observations and without the need of any
additional dark matter; c) there is an intrinsic difficulty in extracting
information about the possibility of a scale-dependent massive scalar field (or
more generally about a varying gravitational constant) from supernovae type Ia.
