Dark matter is matter that gives out no observable radiation and is detected by its gravitational interaction alone. Which of these does NOT provide direct evidence for dark matter?
A) separation of visible and dark matter in collisions of galaxy clusters
B) emission from hot intergalactic gas in galaxy clusters
C) gravitational lensing by unseen objects
D) insufficient visible mass to bind galaxy clusters gravitationally

Question

Quizplus · Accepted Answer

The emission from hot intergalactic gas in galaxy clusters is not direct evidence for dark matter. Instead, it is the gravitational effects, such as the separation of visible and dark matter in collisions, gravitational lensing, and the discrepancy between visible mass and the gravitational binding of galaxy clusters, that provide direct evidence for dark matter. The emission from hot gas is related to the baryonic (normal) matter component and does not directly indicate the presence of dark matter.

Dark Matter Is Matter That Gives Out No Observable Radiation