Universal Properties of Centripetal Accelerations in Spiral Galaxies

James G. O'Brien, Thomas L. Chiarelli, Philip D. Mannheim

Published 2017-04-12Version 1

In a recent paper McGaugh, Lelli, and Schombert (Phys. Rev. Lett. \textbf{117}, 201101 (2016)) showed that in a plot of the observed centripetal accelerations against those predicted by the Newtonian gravity of the luminous matter in spiral galaxies the data points occupied a remarkably narrow band. While one could summarize the mean properties of the band by drawing a single mean curve through it, we show here that the width of the band is just as physically significant. We show this by fitting the band with the illustrative conformal gravity theory, with fits that fill out the width of the band. We show that at very low luminous Newtonian accelerations the plot can become independent of the visible matter contribution altogether, with luminous matter not just inside individual galaxies but outside of them as well (viz. the rest of the visible universe) jointly producing the band.