Dark matter and energy are not sufficient to explain the formation and evolution of modern galaxies.

Violent phenomena, associated with the end of stars (supernovae), mergers of black holes and neutron stars, supermassive black holes accreting mass from the galactic environment and tidal disruption events, all play a key role in the formation and evolution of the galactic structure through feedback processes.

These violent events emit different kinds of cosmic messengers: gravitational waves and neutrinos probe mostly the deeper layers, while radio waves, high energy photons and cosmic rays probe the latter stages of their evolution.

Source: https://www.ego-gw.it/posters-multimessenger-astrophysics/