Three-dimensional radiative transfer models of clumpy tori in Seyfert galaxies

By M. Schartmann, K. Meisenheimer, M. Camenzind, S. Wolf, K. Tristram, Th. Henning Mpia, Heidelberg, Germany ZAH-LSW Heidelberg, Heidelberg · Germany. 2008

166 citations recorded by the source corpus.

Context. Tori of Active Galactic Nuclei (AGN) are made up of a mixture of hot and cold gas, as well as dust. In order to protect the dust grains from destruction by the surrounding hot gas as well as by the energetic (UV/optical) radiation from the accretion disk, the dust is often assumed to be distributed in clouds. Aims. A new three-dimensional model of AGN dust tori is extensively investigated. The torus is modelled as a wedge-shaped disk within which dusty clouds are randomly distributed throughout the volume, by taking the dust density distribution of the corresponding continuous model into account. We especially concentrate on the differences between clumpy and continuous models in terms of the temperature distributions, the surface brightness distributions and interferometric visibilities, as well as spectral energy distributions. Methods. Radiative transfer calculations with the help of the three-dimensional Monte Carlo radiative transfer code MC3D are used in order to simulate spectral energy distributions as well as surface brightness distributions at various wavelengths. In a second step, interferometric visibilities for various inclination as well as position angles and baselines are calculated, which can be used to directly compare our models to interferometric observations with the MIDI instrument. Results. We find that the radial temperature distributions of clumpy models possess significantly enhanced scatter compared to the continuous cases. Even at large distances, clouds can be heated directly by the central accretion disk. The existence of the silicate 10 µm-feature in absorption or in emission depends sensitively on the distribution, the size and optical depth of clouds in the innermost part of the dust distribution. With this explanation, failure and success of previous modelling efforts of clumpy tori can be understood. The main reason for this outcome are shadowing effects of clouds within the central region. We underline this result with the help of several parameter variations. After adapting the parameters of our clumpy standard model to the circumstances of the Seyfert 2 Circinus galaxy, it can qualitatively explain recent mid-infrared interferometric observations performed with MIDI, as well as high resolution spectral data.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: revealing the inner funnel of dust (2009, background): “Following the pioneering work of Nenkova et al. (2002) on clumpy models, Hönig et al. (2006) and Schartmann et al. (2008) showed that three-dimensional radiative transfer models of clumpy tori were consistent with the low spatial resolution SED data and the J04 interferometricdata of NGC 1068.”
The dusty heart of nearby active galaxies. II. From clumpy torus models to physical properties of dust around active galactic nuclei (2009, methodology): “Several radiative transfer models have been developed to account for 2D or 3D clumpy dust distributions (Nenkova et al. 2002; Dullemond & van Bemmel 2005; Hönig et al. 2006; Schartmann et al. 2008).”
REVERBERATION MEASUREMENTS OF THE INNER RADIUS OF THE DUST TORUS IN 17 SEYFERT GALAXIES (2014, background): “…has been conducted to explain the infrared spectral energy distribution (SED) of AGNs and to understand the dust torus structure (e.g., Pier & Krolik 1992; Nenkova et al. 2002, 2008; Dullemond & van Bemmel 2005; Schartmann et al. 2005, 2008; Hönig et al. 2006; Mor et al. 2009; Deo et al. 2011).”
A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies (2013, background): “Interestingly, the elongation is along the polar direction in both cases, placing the emission in the narrowline region, since neither smooth nor clumpy torus models cannot explain elongations along the polar axis (e.g. Schartmann et al., 2008, , Figs.”
Revisiting the Unified Model of Active Galactic Nuclei (2015, background): “Present day phenomenological models do not yet include different types of grains in different parts of the torus although this has been considered in simpler (from the point of view of radiative transfer) models like Schartmann et al. (2008).”
Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium (2011, methodology): “…to model AGN IR emission, taking into account the clumpy nature of dust surrounding the central source, includes at present only few works:Nenkova et al. (2002, 2008a,b), Dullemond & van Bemmel(2005), Hönig et al.(2006); Hönig & Kishimoto(2010), Schartmann et al.(2008) andKawaguchi & Mori (2011).”
Resolving the mid-infrared cores of local Seyferts (2009, background): “…instead, that dust clouds have significant clumpiness in the AGN tori (e.g., Dullemond & van Bemmel 2005; Hönig et al. 2006; Nenkova et al. 2008a,b; Schartmann et al. 2008) which leads to the observed mid-IR emission from hot illuminated cloud faces in the inner torus regions being largey…”
What drives the growth of black holes (2011, result): “However, these results are consistent 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…”
Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, methodology): “The input parameters of the clumpy torusmodel is presented in table 1 of Schartmann et al. (2008); we used th SEDs produced by varying both orientation angle (see their fig.”
Dusty Star Forming Galaxies at High Redshift (2014, methodology): “…al., 2002; Dullemond and van Bemmel, 2005; Piovan et al., 2006; Nenkova et al., 2008; Takagi et al., 2003; Fritz et al., 2006; Hönig et al., 2006; Schartmann et al., 2008), but here we try to focus on the techniques which have been most commonly employed for SED fitting of high-z dusty…”
TESTING THE UNIFICATION MODEL FOR ACTIVE GALACTIC NUCLEI IN THE INFRARED: ARE THE OBSCURING TORI OF TYPE 1 AND 2 SEYFERTS DIFFERENT? (2011, methodology): “The clumpy dusty torus models (Nenkova et al. 2002, 2008a,b; Hönig et al. 2006; Schartmann et al. 2008) propose that the dust is distributed in clumps, instead of homogeneously filling the torus volume.”
A TWO-PARAMETER MODEL FOR THE INFRARED/SUBMILLIMETER/RADIO SPECTRAL ENERGY DISTRIBUTIONS OF GALAXIES AND ACTIVE GALACTIC NUCLEI (2014, methodology): “Figure 3 provides a comparison of several AGN/quasar infrared templates available from the literature as well as the maximum and minimum curves based on the clumpy torus models of Schartmann et al. (2008).”
DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, background): “The Schartmann et al. (2009) models, however, do account for this effect by separating the grains (similar to the clumpy models in Schartmann et al. 2008), yet no 3–5 µm bump is seen. our best-fit model from Sect.”
TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY (2011, methodology): “The clumpy models reproduce well the near-IR and mid-IR emission of different types of AGN (e.g., Mason et al. 2006, 2009; Nenkova et al. 2008b; Schartmann et al. 2008; Polletta et al. 2008; Mor, Netzer, & Elitzur 2009; Thompson et al. 2009; Nikutta, Elitzur, & Lacy 2009; Ramos Almeida et al. 2009…”
Molecular line emission in NGC 1068 imaged with ALMA: I. An AGN-driven outflow in the dense molecular gas (2014, background): “Over the past few years, a number of studies have demonstrated clumpy torus models (Nenkova et al. 2008a, 2008b; Schartmann et al. 2008; Hoenig & Kishimoto 2010) represent well the nuclear infrared emission of local Seyfert galaxies, provided there is no contamination from extended dust components…”
Three-Dimensional Dust Radiative Transfer ∗ (2013, background): “In particular, high optical depth τ 1 occurs in all star formation regions as well as in AGN tori.”
The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, background): “The empirical SEDs shapes show a much smaller scatter than those of the smooth torus models of Fritz et al. (2006), but are more comparably matched to the expected range of the clumpy torus models of Schartmann et al. (2008).”
Modelling the spectral energy distribution of galaxies - V. The dust and PAH emission SEDs of disk galaxies (2010, methodology): “…Granato & Danese 1994, Efstathiou & RowanRobinson 1995, Nenkova et al. 2002, Dullemond & van Bemmel 2005, Fritz et al. 2006, Hönig et al. 2006, Schartmann et al. 2008,Nenkova et al. 2008. keeping with the decoding approach that we have adopted, we envisage that the model will be well suited…”