Compact Groups of Galaxies

By Eddie Muguza and Young Hun Ji

What are CGG’s?

• Densely packed galaxies spread throughout a small volume of space

• Typically contains three to six galaxies

• 1/10th to 1/100th of the size of loose galaxies as galaxy clusters

• Sites for many galaxy interactions

• Contains less than 1% of galaxies in the universe

Galaxy Mergers in CGG’s

• Faster galaxies in a larger volume of space do not merge or interact as much, and instead go through ‘galaxy harrassment’

• Galaxies in CCG’s tend to collide and merge more due to them being densely packed and slow in velocity

Mergers (continued)

• Galaxy mergers tend to result in a giant single elliptical galaxy

• Merged galaxies tend to be bluer in color, like many of those in CCG’s

Galaxy Collisions• Like mergers, they are more

likely to happen when the galaxies travel slower in a densely packed environment

• The stars and planetary systems themselves do not collide, but the giant clouds of gas collide.

• When this happens, the galaxies begin to collapse under the force of gravity and give birth to starbursts.

Study of CGG’s allow us to simulate various kinds of galaxy interactions, including the collision of the Andromeda galaxy and the Milky Way galaxy, which is to happen in approximately three billion years!