What behavior do galactic rotation curves exhibit to suggest the existence of dark matter in an extended halo
A)Small velocities are seen at large distances from the galactic center.
B)Small velocities are seen at distances close to the galactic center.
C)Large velocities are seen at large distances from the galactic center.
D)Large velocities are seen at distances close to the galactic center.

Question

Quizplus · Accepted Answer

Galactic rotation curves show that the velocities of stars and gas in galaxies are constant or slightly increasing with distance from the center instead of decreasing as expected based on the observed mass of visible matter. This behavior suggests the existence of a large amount of invisible matter, dark matter, which is distributed in an extended halo around the galactic center. In this extended halo, the gravitational influence of dark matter dominates and causes stars and gas to orbit at high velocities even at large distances from the center, consistent with observations. Therefore, large velocities are seen at large distances from the galactic center, which is best represented by choice C.

What Behavior Do Galactic Rotation Curves Exhibit to Suggest the Existence