1	ASTR 4610, Mon. Dec. 8, 2003 Reminders/Assignments Quasars and Active Galactic Nuclei (Ch. 26)
2	Quasars and AGNs
3	Observational Definition
4	Observational Definition
5	Observational Definition
6	Observational Definition
7	Quasar Images 1
8	Quasar Spectrum
9	3C31
10	Many Views of Radio Galaxy Centaurus A
11	A Quasar Tour with animations
12	The AGN “Zoo”
13	Orientation and Unified Models “Unified Models” explain some of the different classes of AGN, particularly type 1 and type 2 Seyferts, via orientation. For specifics, see the Annual Reviews article by Antonucci, 1993, a “bishop” in the “Church of Unification.” Another nice website: http://www.mssl.ucl.ac.uk/www_astro/agn/agn_unified.html
14	Surveys/Catalogs
15	Accretion Disks Black hole is “active” only if gas is present to spiral into it Isolated stars just orbit black hole same as they would any other mass Gas collides, tries to slow due to friction, and so spirals in (and heats up) Conservation of angular momentum causes gas to form a disk as it spirals in
16	AGN Accretion Disks
17	Quasar Spectral Energy Distributions (SEDs) Very nice and relatively brief review article from “Quasars and Cosmology” conference by Belinda Wilkes (CfA), a world expert on the subject: http://nedwww.ipac.caltech.edu/level5/Sept01/Wilkes/Wilkes_contents.html Must account for physical processes producing prodigious luminosity from radio wavelengths through the X-ray and even gamma ray regimes. Particular features of interest include radio-jets and the radio-quiet vs. radio-loud dichotomy, the “big blue bump” that produces the optical/UV energy peak and is thought to arise from an accretion disk, and the far infrared that represents re-radiation by hot dust.
18	Quasar Spectral Energy Distributions (SEDs) Wilkes (1997):
19	AGN Emission Lines
20	AGN Accretion
21	Measuring Black Hole Masses in “Nearby” Galaxies SgrA* in the Milky Way Water Masers in NGC 4258, a few others Spatially Resolved Gas or Stellar Dynamics Using the Hubble Space Telescope (HST)
22	The (slightly) active nucleus of our galaxy Probable Black hole High velocities Large energy generation At a=275 AU P=2.8 yr Þ 2.7 million solar masses Radio image of Sgr A* about 3 pc across, with model of surrounding disk
23	Max Planck Institute’s Galactic Core Group
24	Water Masers in NGC 4258 Based on Greenhill et al. (1995) Warped Disk Model Radial Velocities and Proper Motions Measure a Mass of 4x10⁷ solar masses (20 times more massive than SgrA*)
25	Spatially Resolved Spectroscopy from Space Shows BH Signatures HST STIS shows evidence for a super massive black hole in M84 based on spatially resolved gas dynamics (Bower et al 1997). Can also be done by examining spatially resolved stellar absorption line profiles, plus complex 3D orbital modeling.
26	Virial Mass Estimates M = f (r ΔV²/ G) r = scale length of region ΔV is the velocity dispersion f is a factor of order unity dependent upon geometry and kinematics Estimates therefore require size scales and velocities, and verification to avoid pitfalls (eg. radiative acceleration).
27	Potential Virial AGN Mass Estimators Source Radius X-ray Fe Kα 3-10 R_s Broad-Line Region 600 R_s Megamasers 4x10⁴ R_s Gas Dynamics 8x10⁵ R_s Stellar Dynamics 10⁶ R_s Where Schwarzschild radius R_s = 2GM/c² = 3x10¹³ M₈ cm
28	Reverberation Mapping (RM) Broad lines are photoionized by the central continuum, which varies. The line flux follows the continuum with a time lag t which is set by the size of the broad-line emitting region and the speed of light. Recombination timescales are very short, BLR stable, and continuum source small and central. Review: http://nedwww.ipac.caltech.edu/level5/Sept01/Peterson2/Peter_contents.html
29	Reverberation Mapping (RM) Broad lines are photoionized by the central continuum, which varies. The line flux follows the continuum with a time lag t which is set by the size of the broad-line emitting region and the speed of light. Recombination timescales are very short, BLR stable, and continuum source small and central. Review: http://nedwww.ipac.caltech.edu/level5/Sept01/Peterson2/Peter_contents.html
30	Does the BLR obey the Virial Theorem? Four well studied AGNs, RM of multiple emission lines shows the expected relationship (slope = -2) between time lags and velocities (note each of the three will have different central black hole masses). NGC7469: 8.4x10⁶ M_☼ NGC3783: 8.7x10⁶ M_☼ NGC5548: 5.9x10⁷ M_☼ 3C 390.3: 3.2x10⁸ M_☼
31	Does the BLR obey the Virial Theorem? RM-derived masses follow the same M-sigma relationship as seen for normal galaxies that have black hole masses measured from HST spatially resolved gas or stellar dynamics. Not more points since obtaining sigma for AGN is difficult (the AGN dilutes the stellar absorption line EWs). Good to 0.5 dex
32	Empirically BLR Scales With Luminosity Mentioned previously the Kaspi et al. (2000) result how R ~ L^0.7 (above). This permits the possibility of using single-epoch measurements to estimate black hole masses – much easier!
33	Vestergaard (2002) Single epoch FWHM vs. rms FWHM for Hβ Single epoch L vs. mean L
34	Vestergaard (2002) Single epoch BH Mass vs. RM BH mass
35	Estimating Basic AGN Properties Black Hole Mass (Vestergaard 2002): Luminosity in terms of Eddington Fraction:
36	From Peterson (2002)
37	Quasar Host Galaxies
38	Quasar Images II
39	Quasar Images III: “Starburst-Quasar”
40	Ties to Host Galaxy Evolution
41	Ties to Host Galaxy Evolution
42	The “M-sigma” Relation Black Hole Masses are about 0.1% of the central galactic bulge mass (a big surprise to theorists) and tightest correlation is with the stellar velocity dispersion (after Gebhardt et al. 2000).
43	Conclusions and Future We basically seem to know what AGN are now and how to measure some fundamental properties (BH mass, etc.). Should now help to unravel basic AGN physics (e.g., SEDs, lines, etc. vs black hole mass and accretion rate). Should permit us to study AGN evolution and relationship to galaxy evolution in general. AGN not simply rare, extreme physics, but fundamental part of galaxy evolution.