On the radial acceleration relation of $\Lambda$CDM satellite galaxies
  The radial acceleration measured in bright galaxies tightly correlates with
that generated by the observed distribution of baryons, a phenomenon known as
the radial acceleration relation (RAR). Dwarf spheroidal satellite galaxies
have been recently found to depart from the extrapolation of the RAR measured
for more massive objects but with a substantially larger scatter. If confirmed
by new data, this result provides a powerful test of the theory of gravity at
low accelerations that requires robust theoretical predictions. By using
high-resolution hydrodynamical simulations, we show that, within the standard
model of cosmology ($\Lambda$CDM), satellite galaxies are expected to follow
the same RAR as brighter systems but with a much larger scatter which does not
correlate with the physical properties of the galaxies. In the simulations, the
RAR evolves mildly with redshift. Moreover, the acceleration due to the
gravitational field of the host has no effect on the RAR. This is in contrast
with the External Field Effect in Modified Newtonian Dynamics (MOND) which
causes galaxies in strong external fields to deviate from the RAR. This
difference between $\Lambda$CDM and MOND offers a possible way to discriminate
between them.
