Estimating the Masses of Galaxy Groups: Alternatives to the Virial Theorem

Abstract

Group masses are almost always computed using the virial theorem. Bahcall and Tremaine (1981) studied the reliability of mass estimates based on the virial theorem for the case of test particles orbiting a central mass. They found that virial theorem estimates were both inefficient and biased. We have extended the work of Bahcall and Tremaine by exploring alternative mass estimators to the virial theorem for self-gravitating systems.