Why is the energy source for active nuclei like Seyferts thought to be compact?
A) The sources appear to be single stars in photos.
B) The light can vary over short time intervals.
C) We know the masses of the black holes that lurk there, and can find their radii.
D) They are all strong radio sources, with assigned frequencies by their sizes.
E) Their energy appears to be non- stellar synchrotron radiation.

Question

Quizplus · Accepted Answer

The variability of light over short time intervals indicates that the energy source must be compact, as larger sources would not be able to change their brightness so quickly. This rapid variability suggests that the energy-emitting region is small enough to allow for quick changes in luminosity.

Why Is the Energy Source for Active Nuclei Like Seyferts