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

Question

Quizplus · Accepted Answer

Active galactic nuclei becoming less active as they age implies that we see more of them at large distances (and thus looking back in time) because they were more active in the past. Nearby galaxies, being observed in their current state, are less likely to have active nuclei if this activity diminishes over time.

Most Active Galactic Nuclei Are at Large Distances from Us;