An analysis of 900 optical rotation curves: Dark matter in a corner?

One of the largest H-alpha rotation curve data bases of spiral galaxies cur rently available is that provided by Persic and Salucci (PS) [1], which has been derived by them from unreduced rotation curve data of 965 southern sk y spirals obtained by Mathewson, Ford and Buchhorn (MFB) [2]. Of the origin al sample of 965 galaxies, the observations on 900 were considered by PS 19 95 to be good enough for rotation curve studies, and the present analysis c oncerns itself with these 900 rotation curves. The present analysis shows that the rotation velocity, V, at any radial dis placement, R, in the optical disc of any given spiral galaxy satsifies the law V/R-alpha = V-0/R-0(alpha), where R-0 and V-0 are given as approximate functions of the galaxy's absolute magnitude and surface brightness whilst alpha is an unidentified function of other galaxy parameters - of which the most significant ones will be the relative proportions of the disc, bulge and halo mass-components. It is this latter function which provides the opp ortunity for a dark-matter modelling process which is independent of any pa rticular dynamical theory.