Objectives: Active Galaxies and Quasars
Chapter Objectives:
Some galaxies have very active, energetic, small nuclei that emit hundreds to
thousands of times more energy than an entire normal galaxy emits. The
historical development of our knowledge of quasars and related galaxies will
be delineated in this chapter. The initial controversy over the distance to
and thus the nature of these quasi-stellar objects and the evidence pointing
to the cosmological interpretation will be presented. The current consensus
concerning the source of the tremendous energy emitted by quasars and active
galactic nuclei - supermassive black holes - will be discussed and the
supporting evidence explained.
Chapter Skills:
After studying this chapter you should be able to
- Give the history of the discovery of quasars and the reason for the name "quasar".
- List the characteristics of quasars and quasistellar objects.
- Discuss the "energy problem" associated with quasars.
- Describe Seyfert galaxies and BL Lac objects and their similarities to quasars.
- Outline the method used to estimate distances to quasars and discuss the inherent uncertainties in these distances and resulting look back times.
- Show how synchrotron radiation may be produced in an active galaxy.
- Present the evidence that makes a rotating supermassive black hole the best explanation for the energy source of quasars and active galaxies.