Virial Coefficient and Hidden Mass in the Galaxy Groups

Abstract The purpose of this work is a verification of the virial mass estimations for small galaxy groups. The dynamical evolution of triple and quintuple galaxies has been studied by the numerical simulations. The dependence of the virial coefficient k(t) versus time was derived. Initially k(0) = 0. The function k(t) has some strong oscillations from 0.02 to 0.99. Generally, these oscillations are quasiperiodical ones. Such a behavior of k(t) is caused by formation in a system of close isolated temporary double subsystems. A strong correlation between the virial coefficient and the least mutual distance in the system is observed.