The acceleration relation in galaxies and scale invariant dynamics:
  another challenge for dark matter
  A relation between the centripetal acceleration g_obs in galaxies and the
gravity due to the baryon distribution g_bar has been found by McGaugh (2016)
and Lelli et al.(2017). It also summarizes properties such as the Tully-Fisher
and Faber-Jackson relations. Below about g_bar= 10E-10 m s^(-2), the observed
relation deviates from the 1:1 line, g_obs being much larger than g_bar. The
acceleration relation is followed by late and early type galaxies, and also by
the dwarf spheroidals where the deviations from the 1:1 line are the largest
ones. These deviations are currently attributed to dark matter.
  We show that the scale invariant theory, with the assumption of the scale
invariance of the empty space, correctly predicts the observed deviations in
the acceleration relation. The large deviations (up to a factor 400) and the
flattening of the acceleration relation observed for the dwarf spheroidal
galaxies are also well described. The presence of dark matter is no longer
necessary in the scale invariant context, which also accounts why dark matter
usually appears to dominate in galactic regions with low baryonic gravities.
