AGN Unification Viewed in the mid-IR Lei Hao Cornell University Spectra

2 Why Mid-IR Seyfert2s, Type II Seyfert1s, Quasars, Type I Narrow emission linesBroad emission lines Silicate dust absorption Silicate dust emission Dust in ISM: oxygen-rich silicates carbon-rich grains

3 Why Mid-IR Seyfert2s, Type II Seyfert1s, Quasars, Type I Narrow emission linesBroad emission lines Silicate dust absorption Silicate dust emission Dust in ISM: oxygen-rich silicates carbon-rich grains Low resolution modules (SL,LL) Low resolution modules (SL,LL) 5-40  m wavelength coverage 5-40  m wavelength coverage Resolution: Resolution: High resolution modules (SH, LH) High resolution modules (SH, LH) 9-38  m wavelength coverage 9-38  m wavelength coverage Resolution: 600 Resolution: 600

4 Mid-IR spectra examples QSO ULIRG Seyfert Starburst Silicate features Si-O stretching O-Si-O bending

5 AGN mid-IR spectra ULIRGs quasars

6 Seyfert1Seyfert2 AGN mid-IR spectra

7 Spitzer archival available, complete Spitzer archival available, complete low-res spectra, z<0.5 low-res spectra, z<0.5 Optical classification adopted from Veron- Cetty & Veron (2006) Optical classification adopted from Veron- Cetty & Veron (2006) 24 quasars (3 ULIRGs), 45 Seyfert 1s (7 ULIRGs), 47 Seyfert 2s (7 ULIRGs) and 98 ULIRGs. 24 quasars (3 ULIRGs), 45 Seyfert 1s (7 ULIRGs), 47 Seyfert 2s (7 ULIRGs) and 98 ULIRGs. A sample of local AGNs and ULIRGs

8 Mid-IR average spectra Mid-IR average spectra Hao et al. 2007, ApJ, 655, L77

9 Mid-IR average spectra Mid-IR average spectra (Brandl et al., 2006)

10 Deep silicate absorption in ULIRGs SE SA Hao et al. 2007, ApJ, 655, L77

11 Silicate features in Seyferts are week Silicate features in Seyferts are week Deo et al. 2007, / /

12 Many Seyfert 1s show absorptions: Clumpy unification Host galaxy contamination The probability of Seyfert 1s showing SA is larger than the probabilities of Seyfert 2s showing SE. SE SA Hao et al. 2007, ApJ, 655, L77

13 SE SA Hao et al. 2007, ApJ, 655, L77 Silicate features in Quasars are mainly in emission Silicate features in Quasars are mainly in emission

14 Maiolino et al. 2007, A&A,

15 Silicate features in AGN Silicate features in AGN We finally detected the emission feature in QSOs. We finally detected the emission feature in QSOs. Caution: does the emission come from the torus or host galaxies? Caution: does the emission come from the torus or host galaxies? Emission vs. absorption for Type I and Type II are clearer for high-luminosity AGN. Emission vs. absorption for Type I and Type II are clearer for high-luminosity AGN. Seyferts have weak silicate features, many Seyfert 1s have silicate absorptions. Seyferts have weak silicate features, many Seyfert 1s have silicate absorptions. Hao et al. 2005c, ApJ, 625, L75 See also Siebenmorgen et al. 2005, Sturm et al., 2005

16 PAH (Polycyclic Aromatic Hydrocarbon) emissions (C-H and C-C stretching and bending modes) Mid-IR spectra examples QSO ULIRG Seyfert Starburst

17 Weedman, et al PAH strength trace the Starformation in the hosts PAH strength trace the Starformation in the hosts

18 Unification: Type I and Type II AGN should have comparable PAH strength.

19 Mid-IR average spectra Mid-IR average spectra (Brandl et al., 2006)

20 Mid-IR average spectra Mid-IR average spectra PAH emissions are stronger in Seyfert 2s than in Seyfert 1s Similar in Buchanan et al. (2006) and Deo et al. (2007) Need a control sample

21 PAH stronger in Seyfert 2s? Over 60 optically selected Seyfert 1s and Seyfert 2s sampled over their [OIII] luminosities. Seyfert 2s Seyfert 1s Hao et al., in preparation

22 Mid-IR spectra examples QSO ULIRG Seyfert Starburst

23 Since IR is less sensitive to extinction, Then, Unification: Type I and Type II AGN have comparable IR emission line properties?

24 Deo et al Mid-IR atomic emission lines Deo et al. (2007): Seyfert 1s have stronger [OIV]25.89/[NeII]12.81, [NeIII]15.56/[NeII]12.81, and [NeV]14.32/[NeII]12.81 than Seyfert 2s. Enhanced [NeII] emission in Seyfert 2s? Dudik et al. (2007): Seyfert 2s have lower [NeV]14.3/[NeV]24.3 ratios than Seyfert 1s: extinction to [NeV] emitting region? Dudik et al. 2007

25 Conclusion Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … In general, the observations support type II AGN have more obscuration. In general, the observations support type II AGN have more obscuration. But the dust structure in AGN is more complicated. But the dust structure in AGN is more complicated.

26 Conclusion Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … In general, the observations support type II AGN have more obscuration. In general, the observations support type II AGN have more obscuration. But the dust structure in AGN is more complicated. But the dust structure in AGN is more complicated.

27 Conclusion Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … Mid-IR spectrum is a power tool in testing and constraining the unified view of AGN: silicate features, PAH emissions, atomic lines, continuum … In general, the observations support type II AGN have more obscuration. In general, the observations support type II AGN have more obscuration. But the dust structure in AGN is more complicated. But the dust structure in AGN is more complicated.