Modified Newtonian Dynamics and the "Dearth of Dark Matter in Ordinary Elliptical Galaxies"

Abstract

The recent findings of Romanowsky et al., of an ``unexpectedly'' small mass discrepancy within 5 effective radii in several elliptical galaxies, are not surprising in the context of MOND. As we show here, they are, in fact, in full concordance with its predictions. One is dealing with high-surface-density galaxies with mean accelerations rather larger than the acceleration constant of MOND. These findings continue, and are now the extreme examples of, the trend predicted by MOND: the mass discrepancy sets in at larger and larger scaled radii in galaxies with larger and larger mean surface densities; or, equivalently, mean accelerations.