What happens when two or more galaxies collide?
“Colliding galaxies are common in galaxy evolution. Due to the extremely tenuous distribution of matter in galaxies, these are not collisions in the normal sense of the word, but rather gravitational interaction. Colliding may lead to merging. This occurs when two galaxies collide and do not have enough momentum to continue traveling after the collision. Instead, they fall back into each other and eventually merge after many passes through each other, forming one galaxy. If one of the colliding galaxies is much larger than the other, it will remain largely intact after the merger; that is, the larger galaxy will look much the same while the smaller galaxy will be stripped apart and become part of the larger galaxy. Through-passes are less disruptive of galaxy shapes than mergers in that both galaxies largely retain their material and shape after the pass.” Source and further information:
