In a few billion years, the Milky Way and Andromeda will collide. Chances are, there won't be many spectacular stellar collisions, and there's a pretty good chance that the Solar system (and most other stellar systems) won't be flung out into deep space, or be torn apart by incoming stars. But what about on a larger scale?
The product of the collision - dubbed "Milkomeda" - will be an elliptical galaxy, unlike the Milky Way and Andromeda, which are both spiral galaxies. My question is this:
How will the structure of the spiral arms be effectively destroyed by the collision? What mechanisms will cause them to coalesce, and what structures will take their place?