The Accuracy of Mass Determination in Galaxy Clusters by X-ray Observations

We test the reliability of mass determination in clusters of galaxies by X-ray observations. The true mass in cluster models is compared to the mass derived by the X-ray emission and X-ray temperature of a model assuming hydrostatic equilibrium and spherical symmetry. In general we find good agreement between the X-ray mass and the true mass without any systematic over- or under- estimation. The average deviation within the central 2Mpc has a r.m.s. of 15%.