Below is a figure taken from Pathways to Astronomy, Schneider & Arny 4th edition

The motion of the stars around the galactic center lead "astronomers to conclude that the Milky Way's halo contains much more matter than the disk, and that most of this material emits no as-yet detectable light. They therefore describe this unseen mass as dark matter"

Dark Matter Rotational Velocity.JPG

Milky Way Dark Matter:

1) Stars move at higher velocities as expected at larger distances from galactic center. They seem to be traveling at a roughly constant velocity.

2) Then there should be more mass in the HALO (where the globular clusters and population II stars are)

3) The light from those regions suggest that is matter does not emit light.

4) Dark matter is present everywhere in the galaxy with the density the highest at the center. However, “it appears that the overall fraction of the mass that consists of dark matter is greater in the outer parts of the galaxy, eventually constituting the majority of mass. The dark matter apparently continues well beyond the area where we detect the outermost stars.”

5) Dark matter halo about 10 times more massive than the visible galaxy