A group of scientists are studying observable matter in a cluster of galaxies. They conclude that the cluster has only a small percentage of the mass required to keep it from flying apart. Why does the cluster remain intact?(1 point)

Question

Responses

The orbital speed of the galaxies in the cluster is slow enough to keep the cluster intact.
The orbital speed of the galaxies in the cluster is slow enough to keep the cluster intact.

Baryonic matter provides the mass and gravity needed to keep the cluster together.
Baryonic matter provides the mass and gravity needed to keep the cluster together.

The orbital speed of the galaxies in the cluster is fast enough to keep the cluster intact.
The orbital speed of the galaxies in the cluster is fast enough to keep the cluster intact.

Dark matter provides the mass and gravity needed to keep the cluster together.
Dark matter provides the mass and gravity needed to keep the cluster together.

Answer 1

The correct response is:

Dark matter provides the mass and gravity needed to keep the cluster together.

In galaxy clusters, the visible matter (baryonic matter) does not account for enough gravitational pull to hold the cluster together. Scientists believe that a significant amount of dark matter, which is not directly observable but interacts through gravity, contributes to the overall mass of the cluster, providing the necessary gravitational glue to keep the galaxies from flying apart.