Are Galactic Clusters Hypermassive Spherically Symmetric Black Holes?

The possibility of estimating the parameters of alternative gravity theories from observations of galactic cluster “turnaround points” has been discussed in a recent publication. It was assumed that the gravitational field of a galactic cluster in the standard version of general relativity is described by the Schwarzschild-de Sitter metric. The authors of this paper asserted that they had obtained estimates of the parameters of alternative gravity theories from observations of galactic clusters, but no comparison of the theory with observations was made in the paper, and the authors assumed that the theoretical description of turning points in GR and the alternative theories under consideration should be similar. In this study, we conclude that theoretical models such as static spherical black holes can hardly be used to obtain constraints on the parameters of alternative gravity theories by analyzing the differences in the turning radii in these theories and GR, based on observations of galactic clusters.