Tidal change in the energy of a spherical galaxy

Abstract

Tidal effects of a massive perturber on a satellite galaxy have been studied by numerical simulations. The model consists of a spherical satellite galaxy and a point-mass perturber and the encounter is non-penetrating. A wide range of density ratios and eccentricities of the orbit have been used. The disruption of the satellite galaxy has been observed when the numerical value of the fractional change in the energy is greater than two. The energy change shows smooth variation with time in the case of unbound orbits and irregular variation in the bound orbit cases. It is shown that, for a constant pericentric distance, increasing the density ratio decreases the tidal effects, and for a given density ratio an increase in the eccentricity decreases the tidal effects. N-body results are compared with predictions of analytical estimates.