Powered by central black holes, they emit vast quantities of energy into the universe. By their brilliance, quasars show the whole universe all they can. Car-crash Victim NGC 1143. Ring galaxies are the prettiest crash victims in the universe. Fertile Mother M82.
Some galaxies produce lots of infant stars.
The cause may be chains of supernovae or simply ordinary physics that compresses gas, setting off waves of star births in newly bright spiral arms. Bully NGC 4889. They are the bullies of the cosmos, growing by cannibalizing smaller galaxies. Omnipresent Coma Berenices Galaxy Cluster. Galaxy clusters approximate this tense environment with a crowd of ellipticals and lenticulars.