Intergalactic Matter Model for the Missing Mass in the Coma Cluster of Galaxies

Abstract We propose a model of the Coma cluster of galaxies which is composed of the observed visible galaxies and hypothetical invisible intergalactic objects, the latter accounting for the “missing mass.” Numerical simulations are performed of the motion of the member galaxies in the gravitational field of the invisible objects. The dynamical friction due to the invisible objects on the galaxy causes a segregation of galaxies by mass. It is shown by the simulations that this model can well explain the observed mass segregation of the member galaxies.

A comparison of the calculated mass segregation with the observed one indicates that the mass-to-luminosity ratio of the member galaxy lies between 10M⊙/L⊙ and 30M⊙/L⊙ in the present model. This implies that the member galaxy of the Coma cluster cannot have a massive halo of a mass-to-luminosity ratio larger than 30 M⊙/L⊙.