The most active galactic nuclei are usually found at large distances from us;relatively few nearby galaxies have active galactic nuclei.What does this imply?
A)Supermassive black holes existed only when the universe was young and no longer exist today.
B)Active galactic nuclei tend to become less active as they age.
C)Active galactic nuclei can form only at large distances from the Milky Way.
D)The jets seen in many active galactic nuclei must cause them to move far away from us.

Question

Quizplus · Accepted Answer

The fact that relatively few nearby galaxies have active galactic nuclei implies that these nuclei tend to become less active as they age. This is supported by observations that suggest most active galactic nuclei were more active in the past. Option A is incorrect because there is evidence that supermassive black holes exist in the centers of most galaxies, including our own Milky Way. Option C is incorrect because there is no evidence that active galactic nuclei can form only at large distances from the Milky Way. Option D is incorrect because there is no evidence that the jets seen in many active galactic nuclei cause them to move far away from us.

The Most Active Galactic Nuclei Are Usually Found at Large