Chapter 34, Problem 7RQ

To determine

The entity that is thought to be at the center of most large galaxies.

Answer to Problem 7RQ

The entity that is thought to be at the center of most large galaxies is massive black hole.

Explanation of Solution

Many galaxies are active because of their giant galactic cores, which acts as the source of energy. These galactic cores that hosts a black hole, which is massive in size. The black hole is approximately millions times larger than the size of the Sun.

A "supermassive black hole" is the largest type, which holds mass billions of times more than the Sun. It is large as our solar system and is located at the center of the galaxy. The active galaxies are set apart by the black hole, in which a large amount of matter falls continuously. The gravitational force is so powerful that no particle or radiation can escape from it.

Conclusion:

Therefore, the entity that is thought to be at the center of most large galaxies is massive black hole.