Testing emergent gravity with mass densities of galaxy clusters
  We use a sample of 23 galaxy clusters to test the predictions of emergent
gravity (EG) as alternative to dark matter. Our sample has both weak-lensing
inferred total mass profiles as well as x-ray inferred baryonic gas mass
profiles. Using nominal assumptions about the weak-lensing and x-ray mass
profiles, we find that the EG predictions (based on no dark matter) are
acceptable fits only near the virial radius. In the cores and in the outskirts,
the mass profile shape differences allow us to confirm previous results that
the EG model can be ruled out at $>5\sigma$. However, when we account for
systematic uncertainties in the observed weak-lensing and x-ray profiles, we
find good agreement for the EG predictions. For instance, if the weak-lensing
total mass profiles are shallow in the core and the x-ray gas density profiles
are steep in the outskirts, EG can predict the observed dark matter profile in
$0.3 \le r \le 1$R$_{200}$, where R$_{200}$ is the radius which encloses
200$\times$ the critical density of the Universe. The required x-ray and
lensing shapes are within the current observational systematics-limited errors
on cluster profiles. We also show that EG itself allows flexibility in its
predictions, which can allow for good agreement between the observations and
the predictions. We conclude that we cannot formally rule our EG as an
alternative to dark matter on the cluster scale and that we require better
constraints on the weak-lensing and gas mass profile shapes in the region $0.3
\le r \le 1$R$_{200}$.
