Review Questions

1. Briefly describe the pioneering observations and findings of Fath (1909) and of Seyfert (1943). Describe the spectra they observed. 

2. What is a AGN? In terms of emission line strengths and profile shapes in their spectra, what are the defining differences between Seyfert I and Seyfert II galaxies?

3. As a class of active galaxies, why are Markarian (MRK) objects a grab bag of other active galaxy classes?

4. What does BPT stand for? What is a BPT diagram and what different quantities are plotted on it? What can the locus of points on a BPT diagram diagnose about a galaxy? What is the Klewey extension to the BPT diagnostic.

5. Consider Figure 17.1. If a galaxy classifies as an AGN/Seyfert galaxy, it will have an [OIII]/Hβ line ratio of 0.25 ≤ log([OIII]/Hβ) ≤ 1. What would the range of [SiII]/H⍺, [NII]/H⍺, and [OI]/H⍺ line ratios be, respectively?

6. Compare the star formation rate, specific star formation rate, and star formation density of the Milky Way to an "average" starburst" galaxy. Explain why the spectra of starburst galaxies commonly exhibit P-Cygni profiles.

7. Given that AGN and quasars are powered by the same physics, an accreting supermassive black hole in the galactic center, what main property distinguishes an AGN from a quasar? What is/are the historical reason(s) as to why AGN and quasar are treated as separate populations of galaxies.

8. Compare and contrast the spectra of S1.0, NLS1.5, and S2.0/HI AGN.  First concentrate on the Balmer lines and then concentrate on the narrow forbidden lines. What are some possible physical reasons that these spectra differ in the way they do?

9. Consider Figure 17.4, which shows composite quasar spectra. Why is there so much uncertainty in the spectral shape blueward of the Ly⍺ emission line? How do different researchers estimate the flux in this spectral region?

10. What are the six major classes of quasars? Describe the most distinctive/defining property of each?

11. In what different ways are the spectra of quasars observed to vary? Why is it significant that quasars are variable? Why are some programs working so hard to observationally characterize quasar variability?

12. What is the quasar main sequence (what quantities are plotted)? What is the astrophysical utility of the quasar main sequence (what is learned about quasars)?

13. What is a BAL?  What is a NAL?  How is the maximum velocity, vmax , of a quasar wind related to or scale with the quasar luminosity?

14. Compare and contrast the two main classes of models of quasars designed to explain BALs and NALs: (1) equatorial wind models (see Figures 17. 10-17.12), and (2) bi-polar wind models (see Figures 17.13-17.14). What is the essence of evolutionary scenarios?

Problems

1. Under construction