The dusty heart of nearby active galaxies. II. From clumpy torus models to physical properties of dust around active galactic nuclei

By S. Hönig, M. Kishimoto. 2009

177 citations recorded by the source corpus.

With the possibilities of high spatial resolution imaging and spectroscopy as well as infrared (IR) interferometry, the dusty environments (= “dusty torus”) of active galactic nuclei (AGN) are now in reach of observations. Following our Paper I on ground-based mid-IR spectro-photometry, we present an upgrade to our radiative transfer model of three-dimensional clumpy dust tori. The upgrade with respect to earlier work concerns an improved handling of the diffuse radiation field in the torus, which is approximated by a statistical approach. The models are presented as tools to translate classical and interferometric observations into characteristic properties of the dust distribution. We compare model spectral energy distributions (SEDs) for different chemical and grain-size compositions of the dust and find that clouds with standard interstellar matter (ISM) dust and optical depth τV ∼ 50 appear in overall agreement with observed IR SEDs. By studying parameter dependencies, it is shown that type 1 AGN SEDs, in particular the mid-IR spectral index, can be used to constrain the radial dust cloud distribution power law index a, while other parameters are more difficult to assess using SEDs only. Interferometry adds important additional information for modeling when it is interpreted concurrently with the SED. Although type 2 AGN can in principle be used to constrain model parameters as well, obscuration effects make the analysis more ambiguous. We propose a simple, interferometry-based method to distinguish between “compact” and “extended” radial dust distributions without detailed modeling of the data and introduce a way to easily determine individual or sample average model parameters using the observed optical depth in the silicate feature and the mid-IR spectral index.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/10a94a6646a6a5ba9bd000c727c37be16b9bc659

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Citations in the corpus

The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “Such a behaviour is in fact predicted by Hönig & Kishimoto (2010) where the contribution of the MIR emission to the bolometric luminosity depends on the distribution of the dust and blue MIR spectral slopes would come from a compact distribution with most of the emitting dust mass confined close…”
The subarcsecond mid-infrared view of local active galactic nuclei – I. The N- and Q-band imaging atlas (2013, methodology): “The CAT3D models (Hönig & Kishimoto 2010) and the CLUMPY models (Nenkova et al. 2008b) resemble classical clumpy tori made up of spherical clouds, while CAT3DWIND (Hönig & Kishimoto 2017) includes an additional hollow cone in the polar region, representing a dusty wind driven by radiation pressure.”
Stellar and Quasar Feedback in Concert: Effects on AGN Accretion, Obscuration, and Outflows (2015, background): “…large (∼ 1dex) variation in obscuring columns even at roughly fixed polar angle – similar to observational suggestions of “clumpy” torii (Risaliti et al. 2002; Mason et al. 2006; Sánchez et al. 2006; Nenkova et al. 2008; Ramos Almeida et al. 2009; Hönig & Kishimoto 2010; Deo et al. 2011).”
The dust covering factor in active galactic nuclei (2016, methodology): “Thus, model SEDs obtained with MCRT method are applicable to any given source luminosity and distance (see Hönig & Kishimoto 2010 for more details).”
What drives the growth of black holes (2011, background): “…with clumpy torus models (e.g., Nenkova et al., 2002; Elitzur & Shlosman, 2006; Nenkova et al., 2008; Schartmann et al., 2008; Hönig et al., 2006; Hönig & Kishimoto, 2010), which predict no inclination-angle dependence on the strength of the mid-IR emission (see Mullaney et al. 2011a for full…”
DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, methodology): “The brightness distribution of these models usually predicts circular mid-IR emission or elongations along the torus mid-plane (e.g. Granato et al. 1997; Schartmann et al. 2005; Hönig et al. 2006; Schartmann et al. 2008; Hönig & Kishimoto 2010; Stalevski et al. 2012; Heymann & Siebenmorgen 2012).”
TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY (2011, methodology): “…distributions (e.g., Pier & Krolik 1993; Granato & Danese 1994; Efstathiou & RowanRobinson 1995) have been superseded by more complex clumpy dust distributions (e.g., Nenkova, Ivezic, & Elitzur 2002; Hönig et al. 2006; Nenkova et al. 2008a, 2008b; Schartmann et al. 2008; Hönig & Kishimoto 2010).”
The dusty torus in the Circinus galaxy: a dense disk and the torus funnel (2013, unknown): “For this reason, radiative transfer calculations of clumpy dust distributions have been carried out more recently (e.g. Nenkova et al. 2002; Schartmann et al. 2008; Hönig & Kishimoto 2010).”
Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium (2011, methodology): “The model developed byHönig et al.(2006) and its further development (Hönig & Kishimoto 2010), also adopts a Monte-Carlo technique to solve the radiative transfer problem, calculating the SEDs for various phase angles, for each cloud, setting up in this way a database of clumps emission.”