Edge-on views of the tidal debris discs in the merger model 7.5deg100vel (left panel) and the fly-by model 5deg200vel (right panel) at the end of the calculations. Retrograde particles are plotted in red onto prograde particles (green), both are plotted on top of 20 000 particles arbitrarily selected from the target galaxy (blue). In the merger case, only the first 20 000 particles of the pro- and retrograde population are plotted. The tidal debris form a disc around the central galaxy which is oriented in the plane of the interaction. Note that the thickness of the tidal debris distribution is less than the thickness of the MW DoS (Metz et al. 2007; Kroupa et al. 2010). In a less-ideal interaction geometry (e.g. when the infalling disc or the galaxy-orbit is not perfectly perpendicular to the target disc) and through subsequent dynamical evolution, the debris-disc can be expected to be thicker. See the on-line edition of the article for a colour version of this figure.