What is the essential function of the dark matter halo for rotating galaxies?

Answer

Providing the deep gravitational potential well required to keep orbiting material bound.

The mass of the dark matter halo creates a sufficiently deep gravitational potential well, which is crucial for overcoming the high orbital speeds of stars and preventing them from flying off into intergalactic space.

What is the essential function of the dark matter halo for rotating galaxies?
galaxystructuretimegravitydark matter