Galaxy dynamics predictions in the nonsymmetric gravitational theory

In the weak field approximation, the nonsymmetric gravitational theory (NGT) has, in addition to the Newtonian gravitational potential, a Yukawa-like potential produced by the exchange of a spin 1+ boson between fermions. If the range r0 = μ−1 is 25 kpc, then this additional potential due to the interaction with matter in the halos of galaxies can explain the flat rotation curves of galaxies and the Tully-Fisher law (L ∼ υ4) without the dark matter hypothesis. Possible fits to clusters of galaxies and gravitational lensing observations are discussed. The results are based on a linear approximation to a new perturbatively consistent version of the NGT field equations, which does not violate the weak equivalence principle.