The Development of Gas/Star Offsets in Tidal Tails

Abstract

We present models of interacting galaxies in order to study thedevelopment of spatial offsets between the gaseous and stellarcomponents in tidal tails. Observationally, such large-scale offsets areobserved in several systems-most notably NGC 3690-suggesting aninteraction between the tidal gas and some (unseen) hot interstellarmedium (ISM). Instead, our models show that these offsets are a naturalconsequence of the radially extended H I spatial distribution in diskgalaxies, coupled with internal dissipation in the gaseous componentdriven by the interaction. This mechanism is most effective in systemsinvolved in very prograde interactions and explains the observedgas/star offsets in interacting galaxies without invoking interactionswith a hot ISM, starburst ionization, or dust obscuration within thetails.