Do dwarf galaxies form in tidal tails ?

The formation of tidal dwarf galaxies (TDGs) inside tidal arms of interacting disc galaxies has been studied with N-body and N-body/Smoothed Particle Hydrodynamics (SPH) simulations at different resolutions. In pure N-body simulations, no bound objects are formed at high resolution. At low resolution, bound objects can form in tidal tails in agreement with previous work. We conclude that TDGs are not likely to form by pure collisionless collapse in tidal tails. However, the presence of a sufficiently massive and extended gas component in the progenitor disc supports the formation of bound stellar objects in the tidal arms. Our results clearly favour a dissipation supported scenario in which the formation of TDGs is induced by the local collapse of gas which then triggers the collapse of the stellar component.