LINEAR POTENTIALS AND GALACTIC ROTATION CURVES

We present a simple, closed-form expression for the potential of an axisymmetric disk of stars interacting through gravitational potentials of the form V(r) = -beta/r + gammar/2, the potential associated with fundamental sources in the conformal invariant fourth-order theory of gravity which has recently been advanced by Mannheim and Kazanas as a candidate alternative to the standard second-order Einstein theory. Using the model, we obtain a reasonable fit to some representative galactic rotation curve data without the need for any nonluminous or dark matter. Our study suggests that the observed flatness of rotation curves might only be an intermediate phenomenon rather than,an asymptotic one.