The radial acceleration relation in galaxy clusters
  Recently, the discovery of the radial acceleration relation (RAR) in galaxies
has been regarded as an indirect support of alternative theories of gravity
such as Modified Newtonian Dynamics (MOND) and modified gravity. This relation
indicates a tight correlation between dynamical mass and baryonic mass in
galaxies with different sizes and morphology. However, if the RAR relation is
scale-independent and could be explained by alternative theories of gravity,
this relation should be universal and true for galaxy clusters as well. In this
article, by using the x-ray data of a sample of galaxy clusters, we investigate
if there exists any tight correlation between dynamical mass and baryonic mass
in galaxy clusters, assuming hot gas mass distribution almost representing
baryonic distribution and that the galaxy clusters are virialized. We show that
the resulting RAR of 52 non-cool-core galaxy clusters scatters in a large
parameter space, possibly due to our simplifying assumptions and unclear matter
content in galaxy clusters. This might indicate that the RAR is unlikely to be
universal and scale-independent.
