What I learned during my Xi’an “Vacation” Joe Shields Ohio University Essay:

To make sense of it all we just need to understand… DUST

Reasons to pay attention to dust 1.Dust central to understanding the torus - it ’ s small, but resolved (Jaffe, Davies) - it ’ s clumpy (Elitzur, Hoenig poster, … ) - it defines the boundary of the BLR (Laor, Suganuma)

Broad Emission Line NIR(K-band) Broad-emission line lags for objects that also have infrared lags Including Hi & Lo ionization lines) (nucleus) The Central Engine of Active Galactic Nuclei Xi’an, Oct , 2006 Reverberation Radius of Inner Dust Torus Suganuma et al. Lag time vs. Optical Luminosity with BLR lags F9: Clavel et al. (+89) Rodriguez-Pascual et al. (+97) Peterson et al. (04) N3783: Reichert et al. (+94) N7469: Wanders et al. (+97) Kriss et al. (00) Collier et al. (+98) N5548: Peterson et al. (02) Krolik et al. (1991) Peterson & Wandel. (+99) Dietrich et al. (+93) Korista et al. (+95) N4151: Clavel et al. (+90) Maoz et al. (+91) Kaspi et al. (+96) N3227: Winge et al. (+95) Onken et al. (03) Shemmer et al. (04)

Reasons to pay attention to dust 2.Dust explains why Seyfert 2s exist - obscuration of BLR as a function of orientation - disappearance of BLR at low luminosity? (Elitzur, related to wind; Laor related to inner radius) N.B. Remember Ed Moran ’ s cautionary words regarding incidence of hidden broad-line regions - strong selection/sensitivity effects (but getting better) - absence of evidence  evidence of absence - lack of x-ray absorption is not diagnostic

Reasons to pay attention to dust 3.It ’ s an essential part of the NLR - radiation pressure on dust determines ionization structure? (Groves) (complications: star formation, jets - Bennert, Holt, Inskip) 4.It ’ s an important constraint on early star formation associated with AGNs (Hamann) 6

Ways to probe dust in AGNs 1.IR Spectroscopic features (A. Lee, Sturm, Hao, Deo poster … ) -9.7  m feature -PAHs

Mid-IR average spectra (Brandl et al., 2006) L. Hao talk

Ways to probe dust in AGNs 1.IR Spectroscopic features (A. Lee, Sturm, Hao, Deo poster … ) -9.7  m feature -PAHs 2.XAFS in x-ray spectra (J. Lee) 3.Extinction/reddening law (Czerny) !!!! 4.Unification tests - Radio galaxies & quasars (Cleary, Lal, Schulz poster) 9

What Dust Cannot Explain 1.The X-ray absorber in Seyfert 1s - x-ray absorber  infrared absorber (Elitzur, … ) - located on scale similar to BLR (Maiolino); mid-IR emission much more extended - selection effects an issue at high N H Opportunities for study: - time-variability (Risaliti) - “ fossil ” reflection (Maiolino) - XRB constraints for Compton-thick sources

What Dust Cannot Explain 2.Differences between Seyferts and LINERs - amazing dichotomy in BPT diagrams! (Groves)

Brent Groves -NLR Models Sweet Separation Groves, Heckman & Kauffmann (2006) Kewley, Groves et al. (2006)

What Dust Cannot Explain 2.Differences between Seyferts and LINERs - amazing dichotomy in BPT diagrams! (Groves) - probable explanation: different SEDs (Ho) - SEDs really are different - lack of blue bump in LINERs not extinction - see some LINERs as UV sources (Elitzur quoting Maoz) - at low z, M BH different (Constantin, Greene) - low L/L edd  ADAF or RIAF in LINERs

What Dust Cannot Explain 2.Differences between Seyferts and LINERs - amazing dichotomy in BPT diagrams! (Groves) - probable explanation: different SEDs (Ho) - SEDs really are different - lack of blue bump in LINERs not extinction - see some LINERs as UV sources (Elitzur quoting Maoz) - at low z, M BH different (Constantin, Greene) - low L/L edd  ADAF or RIAF in LINERs Tools to probe excitation/energetics: - X-ray (Marquez) - point sources in many cases, not always - IR lines (Chary, Rupke) ** 14

Other New Things 1.A new composite QSO spectrum (Shang)

Results 1 of 3: Spectral Energy Distributions Our sub-sample of 15 objects: Composite spectrum (UV + optical + mid-IR) Normalized at 5600 Å Clear Silicates features around 10 and 18 µm Near-IR composite spectrum (Glikman et al. 2006) 27 AGNs (z<0.4) 1 micron inflexion

Other New Things 1.A new composite QSO spectrum (Shang) 2.Clustering constraint on Seyfert companions (C. Li)

C. Li talk

Other New Things 1.A new composite QSO spectrum (Shang) 2.Clustering constraint on Seyfert companions (C. Li) 3.High-velocity HI absorption wings - tracer of feedback (Morganti) 4.Do star formation indicators break down in presence of luminous AGN? E.g. [OII], PAHs (Levenson) 5.IMF on small scales may be skewed to high masses (Nayakshin) - does this remove observable signatures for t  10 8 yrs? (Cf. Sarzi) 19

Other New Things 6.New metallicity diagnostics for the NLR (Nagao) 7.M-sigma deviations at z=0.37 (Malkan) 8.New tidal disruption candidates (Gezari) 20

Homework: A to-do list 1.Clean up statistics on Sey 1/Sey 2 incidence ? (Elitzur, Martinez-Sansigre) (Moshe: “ Clumpy unification becomes an issue of probability ” ) N.B. don ’ t expect ratios to be same in Optical and X-ray

Clumpy Unification N c (  ) = N 0 exp(-  2 /  2 ) f 2 depends on both  and N 0 !  Type 1 sources from “type 2 viewing”, and vice versa  Flips between type 1 & 2 (Aretxaga et al 99)  f 2 variations may arise from either  or N 0 or both AGN type is a viewing- dependent probability!

A to-do list 1.Clean up statistics on Sey 1/Sey 2 incidence ? (Moshe: “ Clumpy unification becomes an issue of probability ” ) 2.Revisit X-ray absorption vs. Luminosity? (J.X. Wang) 3.Figure out why bars are associated with higher x-ray N H (Maiolino) 4.Be worried about studies that use jet axis as an indicator of torus/disk axis (Jaffe)

Jaffe talk - NGC 1068

A to-do list 1.Clean up statistics on Sey 1/Sey 2 incidence ? (Moshe: “ Clumpy unification becomes an issue of probability ” ) 2.Revisit X-ray absorption vs. Luminosity? (J.X. Wang) 3.Figure out why bars are associated with higher x-ray N H (Maiolino) 4.Be worried about studies that use jet axis as an indicator of torus/disk axis (Jaffe) 5.Find more objects suitable for time-variability studies of x-ray absorption (Risaliti) 25

A to-do list (continued) 6.Start thinking about consequences of reflection of optical light from torus (Gaskell) 7.Worry more about aperture effects (Jaffe, Sturm, Prieto, … ) 8.Gain some more insight into extinction/reddening law ! 9.Look for time variability in Si 9.7  m feature (Gaskell/Ogle) Measure metallicities in high-z, low-L AGNs to address evolutionary issues (Nagao)

A to-do list (continued) Last but not Least: Make plans to visit China again! -The End- 11.Start thinking time-domain science (LSST, EXIST) and other opportunities with new missions