AGN: The Central Kiloparsec A Highly-Biased, Idiosyncratic Introduction 1) Staying just long enough to provoke 2) Meeting organized from the inside out, just like my book; will follow 3) Mention interesting recent results, mostly big questions

From the Central Engine to the Central Kpc rg = 1.5 x 1013 M8 cm = 5 x 10-6 M8 pc inner accretion disk ~ 10 rg BLR ~ 103 – 104 rg ? dusty obscuration ~ 105 rg warm absorbers ~ 105 rg ? galactic feedback arena ~ 106 – 109 rg ??

Computing the Central Engine: r ~ 10 rg Recognition of the MHD turbulence paradigm (+ lots of cycles on big, parallel computers) makes simulation feasible, some with full GR, others with radiation Products include: radial stress and dissipation profiles connecting accretion and jets through their shared magnetic field test of predicted of thermal instability of radiation-dominated regions

Stress continuous across plunging region Shell-integrated fluid-frame EM stress in the inflow Integrated stress in pressure units

How to Measure Radiative Efficiency? Noble & K., in prep. Use total energy equation in 3-d GR MHD code Optically thin toy-model cooling function Parameters: cooling ~ W, H/R = 0.1

Extra Emission Near ISCO, inside Plunging Region Surface brightness in the fluid frame

Radiation-Dominance Is the Natural State of the Interesting Portions of Bright Disks: r < (100 – 1000) rg Radiation pressure exceeds gas pressure for r = g < 1 7 ( L E ) 6 2 M ¯ That is, for the most interesting parts of all bright accretion disks around black holes

Yet a – Model Predicts Thermal Instability When pr > pg k u r & n y e v 1 9 7 6 In the a model, $\int dz Q \propto p_r h$$ Z d z Q » ­ T r Á ® p h h / F = Z d z Q When radiation pressure dominates, p r » Q t c o l ( h = ) ¿ Z d z And T h e r m a l I n s t b i y

Even When pr ~ 10pg , No Runaway! Hirose, K. & Blaes in prep. tcool = 15 orbits

Some Central Engine Questions What determines the fraction of dissipation in the corona? What determines jet strength, radio-loudness? Galactic black holes demonstrate it cannot solely be spin; is magnetic geometry the other parameter? How does either relate to host galaxy morphology?

The Outer Disk and Environs: the BLR & BALR: r ~ (103 – 104) rg Little recent work (as reflected by this conference), but What is the BLR? What is its source of mass? Is it part of, or attached to the disk? Are its dynamics solely gravitational? What about radiation forces, gas pressure, magnetic fields,….? If gravity not dominant, what is the meaning of v2 L1/2 ? What is the BALR? Ditto all the questions above, + where is it? Is the outer disk unstable to fragmentation? That is, is all its heating due to local accretion dissipation?

Obscuration: r ~ 105 rg Parsec-scale, geometrically-thick dusty gas can now be seen directly! VLTI: NGC 1068 Raban et al., submitted to MNRAS

Obscuration Questions Shi & K., 2008 What holds it up against gravity? Can radiation pressure maintain hydrostatic balance? How much gas goes out and how much goes in? What is the physical state and location of both senses of flow? To what degree is it clumped? What makes it clumpy? f=15% f=30% Schartmann et al. 2008 f=60% 0o 60o 90o

Warm Absorbers: r ~ 104 – 106 rg ? Distance indicators: speed, ionization bound, variability V ~ 300 – 1000 km/s ~ 0.001 – 0.003 c: gravitational or other? r ~ [L/(Nx)] (Dr/r) r ~ [ (L/x)(arec Dt)(nX+1/nX)]1/2, e.g. as in Detmers et al. 2008: r(NGC 5548) < 7pc red=1999 black=2002 blue=2005

Warm Absorber Questions What is its source---the BLR? the obscuring torus? Over how wide a range of radii does it extend? It is clearly inhomogeneous---is this due to optical depth effects? Marginal thermal stability? Transient effects of differing sources? What drives its motion? observed range of ionization states

Black Hole Growth: r ~ 1 – 109 rg Mergers and Accretion Are all black holes born in collapse of massive stars? How many seed black holes contribute to a single fully-grown AGN? What fraction of seeds end up in an AGN? What fraction of its mass arrived through mergers and what fraction by accretion? Is there any way to answer these questions with fewer than ~20 free parameters? To what degree are these results altered by merger-recoil escape? (but see Schnittman 2008)

When Will Black Hole Mergers Be Observable? LISA won’t fly any time soon---can we identify mergers some other way while we wait? Is there an EM signal? (Milosavljevic & Phinney, Kocsis et al., Shields & Bonning, Schnittman & K., ……..)

The Black Hole Mass—Bulge Dispersion Correlation The correlation from stellar kinematics Can AGN contribute to the discussion? z=0.5 Tremaine et al. 2002 Woo et al. 2008

Feedback: Do AGN Regulate Cluster Gas Thermodynamics and Galaxy Formation? Cluster scale-- Do jets really heat cluster bubbles, and do they actually restore heat? Is Ljet ~(100—1000)LR?

Outflows revealed by Fe K-edge absorption Galaxy scale-- Typical exploited energy fractions (for galaxy formation) are ~5%; if drawn from the photon output, shouldn’t we be able to see the absorption? If from outflows, does BAL matter carry enough energy? Are there other relevant outflows? Outflows revealed by Fe K-edge absorption PDS 456: Reeves et al. 2008 Why do the hosts of local AGN look so normal?

Does the Host Galaxy Regulate the AGN? What are the relative importance of galaxy mergers and intrinsic galaxy dynamics in controlling the accretion rate onto the nucleus? Is a starburst phase a prerequisite for a bright AGN? Can a host feed a disk faster than Eddington? (If ULXs are strongly super-Eddington, why not larger black holes?)

Summary and Conclusions That’s your job!