The high temperature and pressure of gas in the intracluster medium of galaxy clusters implies that:
A) clusters are in the midst of expanding.
B) clusters host powerful active galactic nuclei.
C) many of the cluster galaxies are obscured by absorption from the intracluster medium.
D) clusters are dominated by dark matter.

Question

Quizplus · Accepted Answer

The high temperature and pressure of the gas in the intracluster medium suggest that galaxy clusters are dominated by dark matter. This is because the gravitational pull of a large amount of mass is required to heat and confine the intracluster gas, and dark matter is the most plausible source of this mass, given that it constitutes about 85% of the total matter in the universe.

The High Temperature and Pressure of Gas in the Intracluster