1. Taxonomy of AGN - circa 1980 Seyfert 1 galaxy Seyfert 2 galaxy QSO
Broad Absorption Line (BAL) QSO
Liner
Quasar
Fanaroff/Riley FR1 and FR2 galaxy
Broad line radio galaxy
Narrow line radio galaxy
Flat Spectrum Core Dominant Radio Source
Steep Spectrum Lobe Dominant Radio Source
BL Lac object
Optically Violent Variable Quasar
“Radio-quiet”
“Radio-loud”

2. Two Basic Resources on Unification
Antonucci, R.R.J. 1993, ARAA, 31, 473 – Unification models for AGN & Quasars
Urry & Padovani 1995, PASP, 107, 803 – Radio loud objects only

3. Spectral “Types” of Emission-Line AGNHa Hg Hb
[O III] 4959,5007
Type 1

4. Ancient History (Rowan-Robinson 1977)

5. Early Evidence for Aspect-dependent Classification
Alignment of optical polarization PA with radio structure in Type 1 objects (polarization typically <1%).
Anti-alignment of optical polarization PA with radio structure in Type 2 objects (polarization 1-5+%).
General alignment of “ionization cones” with radio structure.

6. Radio Structure vs. Optical Polarization (Antonucci 1983)

7. The Hidden Seyfert 1 Nucleus in NGC 1068 (Antonucci & Miller 1985)
Polarized flux
7500 km/sec
Total flux
8 minutes of data in 1998
vs. 20 hrs in 1984!

8. The Hidden Seyfert 1 Nucleus in NGC 1068 (Antonucci & Miller 1985)
Dusty, molecular torus

9. A Slightly More Modern Picture
tv ~ 0.01?
R ~few kpc
tv ~ 100
R ~ pc

10. How the Torus Unifies AGN Classifications
Type 1
Type 1.5
Torus axis does not align with the axis of the galaxy!
Type 1 in polarized light
NLR
BLR
Type 2
Dust grains

11. Polarization at High Inclination (Type 2)
Strong polarization
Perpendicular to torus axis

12. Polarization at Low Inclination (Type 1)
Weak polarization
Parallel to torus axis

13. Clinching Evidence: Direct imaging of Torus (Ford et al. 1997)

14. Clinching Evidence: Images of Ionization Cones (e. g. , Zakamska et al

15. The LINER Galaxy NGC 4258 N E
D = 7 Mpc

16. H20 Maser Emission from NGC 4258 (Miyoshi, Cecil et al. 1992-95)
From Keplerian velocities of masers, central (black hole) mass is 3.6x107 M¤
v µ r -1/2 Keplerian velocity curves

17. Polarized Emission Lines from NGC 4258 (Wilkes et al. 1995)
Dv = 1000 km/s
P.A. = 86o

18. Red and Polarized QSOs from 2MASS (Smith et al. 2000)

19. A Type 2, Red QSO Comes out of the Closet
(Schmidt et al. 2002)
Dv = 30,000 km/s!

20. What is Wrong with these QSOs?
(Smith et al. 2003)

21. Red Type1 QSOs are Polarized!
Type 1 objects
(All show broad lines)

22. Hypothesis for Reddened, Polarized Type 1 QSOs
Reddening/scattering by considerable dust, even in polar directions
Hypothesis for Reddened, Polarized Type 1 QSOs
NLR
BLR
Dust grains

23. Increased Scattering will Cause Reddest QSOs to Appear as Type 1 Regardless of Orientation
Deficit of [O III]
Surplus of [O III]

24. Unification of Radio-Quiet AGN
Liner?
Seyfert 1 galaxy
Seyfert 2 galaxy
Type 1 QSO
BAL QSO?
Type 2 QSO
“Face-on”
“Edge-on”
Luminosity

25. Unification of Radio-Loud AGN
BL Lac object =
Optically Violent Variable Quasar
“Face-on”
Broad line radio galaxy
FR1, FR2,
Narrow line radio galaxy
Flat Spectrum Core Dominant Radio Source
Steep Spectrum Lobe Dominant Radio Source
Quasar
“Edge-on”
Luminosity