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

Question

Quizplus · Accepted Answer

The observation that most active galactic nuclei (AGN) are found at large distances, and thus we see them as they were in the past due to the time it takes light to travel, suggests that AGNs tend to become less active over time. This is because we see fewer AGNs nearby, implying they were more common in the earlier universe and have since become less active or quiescent.

Most Active Galactic Nuclei Are Found at Large Distances from Us