The Modified Newtonian Dynamics Predicts an Absolute Maximum to the Acceleration Produced by “Dark Halos”

We have recently discovered that the modified dynamics (MOND) implies someuniversal upper bound on the acceleration that can be contributed by a `darkhalo'--assumed in a Newtonian analysis to account for the effects of MOND. Notsurprisingly, the limit is of the order of the acceleration constant of thetheory. This can be contrasted directly with the results of structure-formationsimulations. The new limit is substantial and different from earlier MONDacceleration limits (discussed in connection with the MOND explanation of theFreeman law for galaxy disks, and the Fish law for ellipticals): It pertains tothe `halo', and not to the observed galaxy; it is absolute, and independent offurther physical assumptions on the nature of the galactic system; and itapplies at all radii, whereas the other limits apply only to the meanacceleration in the system.Comment: Latex, five pages, final version to be published in Astrophys. J. Let