Tidal effects on a satellite galaxy influenced by a massive perturber

Abstract

The tidal influence on a satellite galaxy by a massive perturber is studied by numerical simulations. The satellite is modelled as a non-rotating spherical cluster of uniform density. The perturber is a galaxy described as a Plummer model. The satellite undergoes penetrating collisions on hyperbolic, parabolic, elliptic and circular orbits. The disruption of the satellite, in parabolic and elliptic encounters, is estimated in terms of the density ratio ρ/ρ_R where ρ is the mean density of the satellite and ρ_R a critical density, the Roche density. In these models the satellite suffers disruption when ρ <ρ_R and survives the tidal encounter otherwise. The survival of the satellite strongly depends on the distance of closest approach. The direction of the orbital angular momentum after the encounter is aligned with that of the initial orbital angular momentum of the pair. Our results also suggests that disruption of the satellite occurs for values of ρ/ρ_R< 3 in circular orbit encounters. In hyperbolic encounters the satellite galaxy is seen to suffer considerable damage only in the case of near head-on collision.