Question

Which of the following statements about rich clusters of galaxies (those with thousands of galaxies) is not true?

A) They are sources of X-ray emission due to the presence of hot, intergalactic gas.
B) There likely have been numerous collisions among the member galaxies at some time in the past.
C) Galaxies in the central regions are predominantly spirals, while elliptical galaxies roam the outskirts.
D) They often have a very large, central dominant galaxy near their center, perhaps formed by the merger of several individual galaxies.
E) The speeds of the galaxies in the cluster indicate that most of the cluster mass is dark matter

Answer 1

The false statement about rich clusters of galaxies is that galaxies in the central regions are predominantly spirals while elliptical galaxies are on the outskirts; the opposite is true.

Step-by-step explanation:

Among the given statements about rich clusters of galaxies, the one that is not true is: C) Galaxies in the central regions are predominantly spirals, while elliptical galaxies roam the outskirts. This statement is inaccurate because in reality, it is the elliptical galaxies that are typically found in the dense central regions of rich galaxy clusters, like the Coma Cluster, while spiral galaxies are more commonly located on the fringes of these clusters.

Rich clusters of galaxies are notable for being sources of X-ray emission due to hot, intergalactic gas that shines brightly at X-ray wavelengths when heated to extremely high temperatures by the kinetic energy of gas particles moving under the cluster's gravity. It's also true that there have likely been numerous collisions among member galaxies in the past and that these clusters often possess a large, central dominant galaxy which may have formed through the mergers of other galaxies.