SIMBAD references

In a sample of 20 rich clusters of galaxies, the mass of the hot X-ray emitting gas is correlated with the square of the gas temperature. Because the hot intra-cluster gas comprises most of the baryonic mass in rich clusters, this correlation implies a mass-velocity dispersion relation of the form seen in elliptical galaxies- the Faber-Jackson relation. Indeed, within the errors and uncertainty in the Hubble parameter, clusters appear to lie on the high mass extention of the Faber-Jackson relation for ellipticals. Although this result is difficult to understand in terms of conventional scenarios for structure formation, it is a direct consequence of Milgrom's modified dynamics (MOND). Applying Milgrom's mass-temperature relation for isothermal spheres to this sample of clusters, one finds agreement between the predicted and observed gas masses to within a factor of two.