Simulations of Compact Groups of Galaxies with Halos

Extract

Self-consistent simulations of seven groups are performed from the maximum expansion to the present using Aarseth's N-body code. An initial galaxy consists of 100 stars. Its mass, half-mass radius, and central velocity dispersion are 1, 0.41, and 0.96. Units of mass, length, velocity, and time are 1.4×10^{1 2}M_⊙, 100 kpc, 245 kms⁻¹ and 4.0×10⁸y. Table 1 gives the elapsed time from the Big Bang to the formation of a multiple merger tm+Tc^*/2. For H₀=80 kms⁻¹Mpc⁻¹, the Hubble time H₀⁻¹=30.6 in our units. Dense groups except B form multiple mergers in a Hubble time.