1. ACTIVE GALAXIES and GALAXY EVOLUTION
Quasars,
Radio Galaxies,
Seyfert Galaxies and
BL Lacertae Objects
Immense powers emerging from ACTIVE GALACTIC NUCLEI:
it’s just a phase they’re going through!

2. Typical Quasar Appearance
Most are actually very faint
BUT their huge redshifts imply they are billions of light-years away and intrinsically POWERFUL
Start here on 11/12

3. Radio Loud Quasar, 3C 175

4. Thought Question
What can you conclude from the fact that quasars usually have very large redshifts?
A. They are generally very distant
B. They were more common early in time
C. Galaxy collisions might turn them on
D. Nearby galaxies might hold dead quasars

5. Thought Question
What can you conclude from the fact that quasars usually have very large redshifts?
A. They are generally very distant
B. They were more common early in time
C. Galaxy collisions might turn them on
D. Nearby galaxies might hold dead quasars
All of the above!

6. Birth of a Quasar Movie Fast variability implies small size
Immense powers emerging from a volume similar to the solar system!

7. SEYFERT GALAXIES Sa, Sb galaxies with BRIGHT, SEMI-STELLAR NUCLEI
NON-THERMAL & STRONG EMISSION LINES
VARIABLE in < 1 yr  COMPACT CORE
Type 1: Broad Emission lines (like QSOs), strong in X-rays
Type 2: Only narrow Emission lines, weak in X-rays
About 1% of all Spirals are SEYFERTS, so
Either 1% of all S's are always Seyferts OR
100% of S's are Seyferts for about 1% of the time (MORE LIKELY)
OR 10% of S's are Seyferts for about 10% of the time (or any other combination of fraction and lifetime)
Start here on 11/29 and 11/30

8. A Seyfert and X-ray Variability
Circinus, only 4 Mpc away; 3C 84

9. More About Seyferts Seyferts are weak radio emitters.
CONCLUSIONS ABOUT SEYFERTS Fundamentally, they are WEAKER QSOs
Type 1: we see the center more directly Type 2: dusty gas torus blocks view of the center

10. BL Lacertae Objects
NON-THERMAL SPECTRUM: Radio through X-ray (and gamma-ray)
Radiation strongly POLARIZED
HIGHLY VARIABLE in ALL BANDS
But (when discovered) NO REDSHIFT, so distances unknown
Later, surrounding ELLIPTICAL galaxies found
CONCLUSION: greatly enhanced emission from the AGN due to RELATIVISTIC BOOSTING of a JET pointing very close to us.
BL Lacs + OPTICALLY VIOLENTLY VARIABLE QUASARS ARE OFTEN CALLED BLAZARS

11. AGN CONTAIN SUPERMASSIVE BLACK HOLES (SMBHs)
KEY LONGSTANDING ARGUMENTS:
ENERGETICS: Powers up to 1048 erg/s (1041W) Even at 100% efficiency would demand conversion of about 18 M /yr (=Mdot) into energy.
Nuclear processes produce < 1% efficiency.
GRAVIATIONAL ENERGY via ACCRETION can produce between 6% (non-rotating BH) and 32% (fastest-rotating BH),and the Luminosity is
L = G MBH Mdot / R,
with R the main distance from the Super Massive Black Hole (SMBH) where mass is converted to energy.

12. Time Variability tVAR = R / c tVAR = 104 s  R = 3 x 1014 cm = 10-4 pc
For L = 1047 erg/s,
M_dot = 10 M /yr we get MBH = 3 x 108 M and RS = 9 x 1013 cm
So, R = 3 RS
MUTUALLY CONSISTENT POWERS AND TIMESCALES.

13. RECENT OBSERVATIONAL SUPPORT
The Hubble Space Telescope has revealed that star velocities rise to very high values close to center of many galaxies and gas is orbiting rapidly, e.g. M87
Disks have been seen via MASERS in some nearby Seyfert AGN.
VLBI: radio jets formed within 1 pc of center.
There are several other more technical lines of evidence also supporting the SMBH hypothesis for AGN.

14. Rapidly Rotating Gas in M87 Nucleus
M87 zoom toward black hole

15. Direct Evidence for Rotating Disk
Masers formed in warped disk in NGC 4258 (and a few other Seyfert galaxies)

16. Evidence for Supermassive Black Holes
NGC 4261: at core of radio emitting jets is a clear disk
~300 light-yrs across and knot of emission near BH

17. SMBH Model for AGN

18. UNIFIED MODELS FOR AGN
Three main parameters: MBH; the accretion rate, M_dot, and viewing angle to the accretion disk axis, 
Main ingredients:
SMBH > 106 M
10-5 pc < accretion disk < 10-1 pc (AD)
broad line clouds < 1 pc (BLR)
thick, dusty, torus < 100 pc
narrow line clouds < 1000 pc (NLR)
sometimes, a JET (usually seen from < 102 pc to maybe 106 pc!)
Start here on 4/16

19. Unification for Radio Quiet and Radio Loud
RADIO LOUD (Jets)
High MBH, M_dot:
 very small: Optically Violently Variable Quasar
 small: radio loud quasar (QSR)
 large: classical double radio galaxy (FR II type)
Low MBH. M_dot:
 very small: BL Lac object
 small: broad line radio galaxy (FR I type)
 large: narrow line radio galaxy
RADIO QUIET
High MBH, M_dot:
 small: QSO is seen including AD and BLR
 large: only NLR plus radiating torus: seen as UltraLuminous InfraRed Galaxies (ULIRGs)
Low MBH, M_dot:
 small: Seyfert Type 1  big: Seyfert Type 2

20. Different AGN from Different Angles
Luminous: Quasars seen close to perpendicular to disk and Ultraluminous Infrared Galaxies near disk plane
Weaker: Type 1 or Type 2 Seyferts
If jets are important:
BL Lacs along jet axis,
Quasars at modest angles & Radio Galaxies at larger angles

21. Black Holes in Galaxies
Many nearby galaxies – perhaps all of them – have supermassive black holes at their centers
These black holes seem to be dormant active galactic nuclei
All galaxies may have passed through a quasar-like stage earlier in time

22. Galaxies and Black Holes
Mass of a galaxy’s central black hole is closely related to mass of its bulge

23. Pop Quiz Print your name (1)
Draw a labeled diagram of the Milky Way as it would be viewed “edge-on”. Be sure to give the overall size of the stellar disk as well as the distance of the solar system from the galactic center (6).
Draw a labeled Hubble “tuning-fork” diagram (I.e., the simplest galaxy classifcation scheme). (4).