Galactic rotation curves in conformal gravity
  We review some recent work by Mannheim and O'Brien on the systematics of
galactic rotation curves in the conformal gravity theory. In this work the
conformal theory was applied to a comprehensive, high quality sample of spiral
galaxies whose rotation curves extend well beyond the galactic optical disks.
On galactic scales the conformal gravitational theory departs from the standard
Newtonian theory in two distinct ways. One is a local way in which local matter
sources within galaxies generate not just Newtonian potentials but linear
potentials as well. The other is a global way in which two universal global
potentials, one linear the other quadratic, are generated by the rest of the
matter in the universe. The study involves a broad set of 138 spiral galaxies
of differing luminosities and sizes, and is augmented here through the
inclusion of an additional three tidal dwarf galaxies. With its linear and
quadratic potentials the conformal theory can account for the systematics of an
entire 141 galaxy sample without any need for galactic dark matter, doing so
with only one free parameter per galaxy, namely the visible galactic mass to
light ratio.
