MOND predictions of "halo" phenomenology in disc galaxies

Abstract

We examine two corollaries of MOND pertaining to the properties of the equivalent dark-matter halo. MOND predicts for pure exponential discs a tight relation involving the halo and disc scale lengths and the mean acceleration in the disc, which we find to test favorably against the Verheijen sample of Ursa Major galaxies. A correlation between halo and disc length scales is also apparent when the "maximum disc" contribution is assumed, but we demonstrate that this follows from the more general MOND prediction. The second MOND prediction involves the existence of a maximum halo acceleration, which also tests favorably against the Ursa Major sample for different assumptions on the disc contribution.