SIMBAD references

We examine the relationship between the mass and X-ray gas temperature of galaxy clusters using data drawn from the literature. Simple theoretical arguments suggest that the mass of a cluster is related to the X-ray temperature as M∝T^3/2_X. Virial theorem mass estimates based on cluster galaxy velocity dispersions seem to be accurately described by this scaling with a normalization consistent with that predicted by the simulations of Evrard, Metzler, and Navarro. X-ray mass estimates that employ spatially resolved temperature profiles also follow a T^3/2_X scaling although with a normalization about 40% lower than that of the fit to the virial masses. However, the isothermal β-model and X-ray surface brightness deprojection masses follow a steeper ∝T^1.8–2.0_X scaling. The steepness of the isothermal estimates is due to their implicitly assumed dark matter density profile of ρ(r)∝r^–2 at large radii, whereas observations and simulations suggest that clusters follow steeper profiles [e.g., ρ(r)∝r^–2.4].