Galaxies form within vast halos of dark matter, whose gravitational pull provides the scaffolding for ordinary matter to collapse.

The prevailing cosmological model, Lambda-CDM, posits that the universe is dominated by dark energy and dark matter. Dark matter, though invisible and interacting only gravitationally, is crucial for galaxy formation. Simulations show that early universe density fluctuations, amplified by gravity, led to the formation of 'halos' of dark matter. These halos act as gravitational wells, attracting baryonic (ordinary) matter, which then cools and condenses at their centers to form stars and, eventually, galaxies. Without dark matter's gravitational influence, the observed large-scale structures and the rapid formation of early galaxies would be impossible.