Chapter 24

What is it about the colors of quasars that makes it easy to distinguish them from most stars and galaxies?

Suppose a quasar is observed to increase tenfold in brightness in 4 years. Approximately how large can the quasar be?

Describe how we can account for the superluminal motions of quasars without requiring components of quasars that are actually moving apart at speeds greater than the speed of light.

Describe the differences between Seyfert 1 and Seyfert 2 galaxies.

What is the relationship between jets and the lobes of radio galaxies?

How could a radio galaxy be observed to have two radio-emitting lobes but only a single jet pointing at one of the lobes?

How can viewing angle account for the differences between quasars and blazars?

How do we know that if black holes power quasars, then those black holes must be very massive?

Explain why, if objects of a particular kind are uniformly distributed through space, we should expect to find about half of them with a \(V / V_{\max }\) less than 0.5 and half with a \(V / V_{\max }\) greater than 0.5.

Under what circumstances can a gravitational lens produce an Einstein ring rather than multiple images of a distant quasar?