The radial acceleration relation and dark baryons in MOND
  Recent observations of rotationally supported galaxies show a tight
correlation between the observed radial acceleration at every radius and the
Newtonian acceleration generated by the baryonic mass distribution, the
so-called radial acceleration relation (RAR). The rotation curves (RCs) of the
SPARC sample of disk galaxies with different morphologies, masses, sizes and
gas fractions are investigated in the context of modified Newtonian dynamics
(MOND). We include the effect of cold dark baryons by scaling the measured mass
in the atomic form by a factor of $c$ in the mass budget of galaxies. In
addition to the standard interpolating function, we also fit the RCs and the
RAR with the empirical RAR-inspired interpolating function. Slightly better
fits for about $47\%$ of galaxies in our sample are achieved in the presence of
dark baryons ($c>1$) with the mean value of $c = 2.4\pm 1.3$. Although the MOND
fits are not significantly improved by including dark baryons, it results in a
decrease in the characteristic acceleration $g_\dag$ by $40\%$. We find no
correlation between the MOND critical acceleration $a_0$ and the central
surface brightness of the stellar disk, $\mu_{3.6}$. This supports $a_0$ being
a universal constant for all galaxies.
