Dusty Winds in Active Galactic Nuclei: Reconciling Observations with Models
Abstract
This Letter presents a revised radiative transfer model for the infrared (IR) emission of active galactic nuclei (AGNs). While current models assume that the IR is emitted from a dusty torus in the equatorial plane of the AGNs, spatially resolved observations indicate that the majority of the IR emission from ≲100 pc in many AGNs originates from the polar region, contradicting classical torus models. The new model CAT3D-WIND builds upon the suggestion that the dusty gas around the AGNs consists of an inflowing disk and an outflowing wind. Here, it is demonstrated that (1) such disk+wind models cover overall a similar parameter range of observed spectral features in the IR as classical clumpy torus models, e.g., the silicate feature strengths and mid-IR spectral slopes, (2) they reproduce the 3-5 μm bump observed in many type 1 AGNs unlike torus models, and (3) they are able to explain polar emission features seen in IR interferometry, even for type 1 AGNs at relatively low inclination, as demonstrated for NGC3783. These characteristics make it possible to reconcile radiative transfer models with observations and provide further evidence of a two-component parsec-scale dusty medium around AGNs: the disk gives rise to the 3-5 μm near-IR component, while the wind produces the mid-IR emission. The model SEDs will be made available for download.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2017
- DOI:
- 10.3847/2041-8213/aa6838
- arXiv:
- arXiv:1703.07781
- Bibcode:
- 2017ApJ...838L..20H
- Keywords:
-
- galaxies: active;
- galaxies: individual: NGC3783;
- infrared: galaxies;
- radiative transfer;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 8 pages, 4 figures, 1 table. Accepted for publication in ApJ Letters. The model SEDs can be downloaded from http://cat3d.sungrazer.org