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1 Dusty Torus Formation by Anisotropic Radiative Feedback of Active Galactic Nuclei Shuang-Nan Zhang, Yuan Liu, Jin Zhang Institute of High Energy Physics.

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Presentation on theme: "1 Dusty Torus Formation by Anisotropic Radiative Feedback of Active Galactic Nuclei Shuang-Nan Zhang, Yuan Liu, Jin Zhang Institute of High Energy Physics."— Presentation transcript:

1 1 Dusty Torus Formation by Anisotropic Radiative Feedback of Active Galactic Nuclei Shuang-Nan Zhang, Yuan Liu, Jin Zhang Institute of High Energy Physics and National Astronomical Observatories of China Chinese Academy of Sciences Liu,Y. & Zhang, S.N., 2011, ApJL, 728, L44

2 2/21 The unified model of AGN Dusty torus Formation ? Evolution ?

3 3/21 AGN feedback The distribution of the dust is anisotropic The UV/optical radiation from the accretion disk is also anisotropic The effect of radiation pressure is significant due to the presence of dust The normal of the accretion disk observer A~500

4 4/21 The evolution of AGNs ABC Momentum effect of radiation

5 5/21 Evaporation radius The inner radius of dust Energy effect of radiation

6 6/21 The profile of a dusty torus

7 7/21 N H -L/L Edd plane Raimundo, Fabian, Bauer et al. 2010

8 8/21 The fraction of type 2 AGNs Hasinger 2008

9 9/21 The inner radius of dusty torus Suganuma et al. 2006

10 10/21 The evolution of dusty torus Luminous, with torus, but without bright BLR

11 11/21 Weak line quasars Shemmer et al. 2009; EW<5 A; continuum similar to normal quasars

12 12/21 Radio quiet BL Lac Plotkin et al No obvious emission lines

13 13/21 Are WLQs and Radio Quiet BL Lac the Objects Predicted by Our Model? Predictions  Luminous accretion disk emission  Existence of Dusty Torus Tests  Low polarization  disk not jet  Low variability  disk not jet  Hot dust emission  torus illuminated by luminous disk

14 14/21 Very low polarization in continuum spectra: only two of 25 candidates are observed with weak polarization (Heidt & Nilsson 2011); non detection for all others The continuum spectrum is consistent with disk origin Polarization Test: radio quiet BL Lac

15 15/21 Long Term Variability Test So far observations are quite limited Weaker than radio loud BL Lac ? Need more observations Plotkin et al. 2010

16 16/21 Long Term Variability Test SDSS Stripe 82 ( 12 radio quiet BL Lac , 4 WLQ , 27 radio loud BL Lac ) Radio quietRadio loud

17 17/21 Lightcurve amplitudes Radio loud Radio quiet

18 18/21 Four SDSS Radio Quiet BL Lac Observed with Lijiang 2.4 m at V, I and R bands SDSS SDSS

19 19/21 Very weak short timescale variability! Time (Hour) m(BL Lac)-m(Star) Short Term Variability Test

20 20/21 Hot Dust Test in weak line quasars Black body from hot dust Diamond-Stanic et al Evidence of hot dust in WLQ

21 21/21 Conclusions The distribution of dusty gas should also be anisotropic due to the influence of the anisotropic disk radiation. Our model can explain the presence of some obscured AGNs with high Eddington ratios and can also reproduce the observed decreasing fraction of type 2 AGNs with increasing luminosity. Our model predicts the existence of luminous AGNs with dusty tori, but without luminous broad line regions.  Weak line quasars and radio quiet BL Lac? Weak polarization, low variability and hot dust feature confirm our model predictions. Liu,Y. & Zhang, S.N., 2011, ApJL, 728, L44


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