Some quasars show absorption spectra with a smaller redshift than their emission spectra;this indicates that:
A)we still don't understand redshifts.
B)they are much closer than previously thought.
C)there is cooler gas between us and the quasar.
D)their black holes are still contracting.
E)their black holes are still expanding.

Question

Quizplus · Accepted Answer

This is known as "quasar absorption lines" and is caused by cooler gas between us and the quasar absorbing certain wavelengths of light. It does not necessarily indicate a closer distance or anything about the state of the quasar's black hole. The fact that some quasars show absorption spectra with a smaller redshift than their emission spectra is an indication that there is cooler gas present between us and the quasar. This cooler gas absorbs some of the light emitted by the quasar, causing a shift in its observed spectrum. This phenomenon is known as the "proximity effect".

Some Quasars Show Absorption Spectra with a Smaller Redshift Than