Gauge choice in conformal gravity

In a recent paper, K. Horne examined the effect of a conformally coupled scalar field ( referred to as Higgs field) on the Mannheim-Kazanas metric g(mu nu)., i.e. the static spherically symmetric metric within the context of conformal gravity, and studied its effect on the rotation curves of galaxies. He showed that for a Higgs field of the form S(r) = S(0)a/(r + a), where a is a radial length-scale, the equivalent Higgs-frame Mannheim-Kazanas metricg(mu nu.) = Omega(2)g(mu nu), with Omega = S(r)/S-0, lacks the linear gamma r term, which has been employed in the fitting of the galactic rotation curves without the need to invoke dark matter. In this brief note, we point out that the representation of the Mannheim-Kazanas metric in a gauge, where it lacks the linear term, has already been presented by others, including Mannheim and Kazanas themselves, without the need to introduce a conformally coupled Higgs field. Furthermore, Horne argues that the absence of the linear term resolves the issue of light bending in the wrong direction, i. e. away from the gravitating mass, if gamma r > 0 in the Mannheim- Kazanas metric, a condition necessary to resolve the galactic dynamics in the absence of dark matter. In this case, we also point out that the elimination of the linear term is not even required because the sign of the gamma r term in the metric can be easily reversed by a simple gauge transformation, and also that the effects of this term are indeed too small to be observed.