The Influence of a Mass Spectrum on the Long Term Evolution of a Self-Gravitating System of Softened Particles

Abstract

Using N-body simulations, we study the effects of the mass spectrum in the evolution of self-gravitating systems of softened point-mass particles. The mass function is described by a power law and the ratio between the maximum and minimum mass is ${\text{10}}^{\text{4}}$. We showed that the dynamical evolution of the system depends on the mass spectrum: the secular evolution time is longer for flatter mass spectrum. For the steepest mass spectrum, the secular evolution time is of the order of the relaxation time. The mass segregation effects are achieved rapidly and the core-halo structures are formed. The projected number distributions for the systems with mass spectrum change drastically with the evolution while the projected mass distributions are not affected. Velocity dispersion profiles are modified in the sense of heating of the central regions of the systems, while the velocity anisotropy profiles are slightly affected. The consequence of our results on the dynamical evolution of clusters of galaxies is presented.