Infrared constraints on dust properties and torus

Dieter Lutz (MPE)

We present results from searches for broad components to the 4micron Brackett alpha line in Type 2 Seyferts, and discuss implications on the dust properties of the obscuring matter. We compare host-free mid-infrared AGN continuum and intrinsic hard X-ray emission for a large sample of nearby Seyferts. The strong orientation effects in the Mid-IR/X ratio that are expected in the most simple unified schemes are not found in our data, a result that can be explained in terms of contributions of NLR dust to the mid-IR continuum and of the properties of clumpy torus models. We compare upper limits on 4.7um CO bands in local AGN with the recent Spitzer detection of such bands in an obscured AGN ULIRG, suggesting that the difference most likely reflects incomplete vs. full covering of the obscuring matter close to the AGN.

  • PDF