How does angular momentum affect whether a galaxy becomes spiral or elliptical?

In the study of galaxy formation, the angular momentum of the original gas clouds—or protogalaxies—is a primary factor in determining the final shape of the system.1

• Spiral Galaxies: A protogalaxy possessing a large amount of angular momentum tends to collapse into a flat, rapidly rotating system, resulting in the formation of a spiral galaxy.1
• Elliptical Galaxies: Conversely, a protogalaxy with very little angular momentum typically develops into a more nearly spherical system, known as an elliptical galaxy.1

While early models focused on the collapse of these clouds, modern cosmology recognizes that galaxy evolution is also significantly influenced by collisions and the accretion of smaller entities, which continue to alter the structure and appearance of galaxies over time.1