Interacting binary galaxies. I - A numerical model and preliminary results

A multiple three-body algorithm (MTBA) numerical code has been developed for the study of interacting binary galaxy evolution which involves N concurrent three-body integrations. The sum of the interactions of the perturber with each of the N particles comprising the primary galaxy determines the binary orbital evolution. MTBA incorporates a violent relaxation phase which allows the particles to redistribute themselves in the gravitational field of the perturber before full binary orbital evolution calculation. Tabulated merger times for both circular and elliptical orbits demonstrate that typical close binary galaxies will merge in approximately twice their initial binary orbital periods, or about one billion years, with this time scale being strongly dependent on binary separation, weakly dependent on mass ratio, and less dependent on initial galaxy rotation than has previously been thought.