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 the central regions are predominantly spirals, while ellipticals are on the outskirts. In reality, giant elliptical galaxies dominate the central areas, and spirals are more common on the outskirts.

Step-by-step explanation:

The statement about rich clusters of galaxies that is not true is: C) Galaxies in the central regions are predominantly spirals, while elliptical galaxies roam the outskirts. This statement is incorrect because in rich clusters like the Coma Cluster, we generally find that the central regions are dominated by giant elliptical galaxies, not spiral galaxies. Spiral galaxies are more commonly found in the outskirts of these clusters. On the contrary, statements A, B, D, and E accurately depict characteristics of rich galaxy clusters such as the presence of X-ray emission from hot intergalactic gas, past collisions among member galaxies, a very large central dominant galaxy potentially formed by mergers, and the presence of dark matter indicated by the speeds of galaxies within the cluster.