What happens to the organized rotational energy of spiral galaxies during a major merger that forms an elliptical?

Answer

It is quickly randomized into the three-dimensional motions of the stars.

When two large spiral galaxies collide violently, their rotational support is destroyed, and the energy is randomized into three-dimensional stellar motions, causing the structure to 'fluff up' into an elliptical shape.

What happens to the organized rotational energy of spiral galaxies during a major merger that forms an elliptical?
galaxieselliptical galaxiesshape