A universal velocity dispersion profile for pressure supported systems:
  evidence for MONDian gravity across 7 orders of magnitude in mass
  For any MONDian extended theory of gravity where the rotation curves of
spiral galaxies are explained through a change in physics rather than the
hypothesis of dark matter, a generic dynamical behavior is expected for
pressure supported systems: an outer flattening of the velocity dispersion
profile occurring at a characteristic radius, where both the amplitude of this
flat velocity dispersion and the radius at which it appears are predicted to
show distinct scalings with the total mass of the system. By carefully
analyzing the dynamics of globular clusters and elliptical galaxies, we are
able to significantly extend the astronomical diversity of objects in which
MONDian gravity has been tested, from spiral galaxies, to the much larger mass
range covered by pressure supported systems. We show that a universal projected
velocity dispersion profile accurately describes various classes of pressure
supported systems, and further, that the expectations of extended gravity are
met, across seven orders of magnitude in mass. These observed scalings are not
expected under dark matter cosmology, and would require particular explanations
tuned at the scales of each distinct astrophysical system.
