DUSTY STRUCTURE AROUND TYPE-I ACTIVE GALACTIC NUCLEI: CLUMPY TORUS NARROW-LINE REGION AND NEAR-NUCLEUS HOT DUST

By Rivay Mor, H. Netzer, M. Elitzur. 2009

187 citations recorded by the source corpus.

We fitted Spitzer/IRS ∼ 2–35 μm spectra of 26 luminous quasi-stellar objects in an attempt to define the main emission components. Our model has three major components: a clumpy torus, dusty narrow-line region (NLR) clouds, and a blackbody-like dust. The models utilize the clumpy torus of Nenkova et al. and are the first to allow its consistent check in type-I active galactic nuclei (AGNs). Single torus models and combined torus–NLR models fail to fit the spectra of most sources, but three-component models adequately fit the spectra of all sources. We present torus inclination, cloud distribution, covering factor, and torus mass for all sources and compare them with bolometric luminosity, black hole mass, and accretion rate. The torus mass is found to be correlated with the bolometric luminosity of the sources. Torus-covering factor may also be (anti-)correlated, if some possibly anomalous points are omitted. We find that a substantial amount of the ∼2–7 μm radiation originates from a hot dust component, which is likely situated in the innermost part of the torus. The luminosity radiated by this component and its covering factor are comparable to those of the torus. We quantify the emission by the NLR clouds and estimate their distance from the center. The distances are ∼700 times larger than the dust sublimation radius, and the NLR-covering factor is about 0.07. The total covering factor by all components is in good agreement with the known AGN type-I:type-II ratio.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0ace5f243195fbed04c3fa966efe78927b8505d7

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In Astronomy and Astrophysics

1. D. M. Alexander
2. P. Hopkins
3. L. Hernquist
4. H. Netzer
5. E. Daddi
6. D. Lutz
7. S. Wuyts
8. R. Genzel

In Instrumentation

1. D. M. Alexander
2. E. Daddi
3. P. Hopkins
4. S. Wuyts
5. L. Hernquist
6. D. Lutz
7. R. Genzel
8. P. V. van Dokkum

Citations in the corpus

• The dusty torus in the Circinus galaxy: a dense disk and the torus funnel (2013, result): “Therefore, the total covering fraction of the dust in the ionisation cone is most likely <10%, which is consistent with the estimate by e.g. Mor et al. (2009).”
• Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium (2011, methodology): “Exploiting the model of Nenkova et al.(2008b), Mor et al. (2009) fit a sample of midinfrared spectra of 26 luminous quasar, finding the need of anex- tra hot-dust component, which they add to the clumpy torus SED, in order to properly reproduce the shorter wavelengths partof the Spitzer spectrum.”
• Cosmic X-ray surveys of distant active galaxies (2015, background): “In recent years, for example, it has become possible to obtain direct estimates of the (luminosity dependent) extent of the torus (e.g., Burtscher et al 2013; Koshida et al 2014) and to ascertain its apparently clumpy nature (e.g., Elitzur and Shlosman 2006; Mor et al 2009).”
• 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 relative strength of this component with respectto the torus emission is a function of the covering factor of NLR clouds, which tends to be quite low (∼ 0.1; Mor et al. 2009), indicating that the NLR contribution to the total AGN IR luminosity is likely to be small.”
• Hot graphite dust and the infrared spectral energy distribution of active galactic nuclei (2011, background): “Dusty gain the narrow-line region (NLR) may be the source of such radiation (Schweitzer et al. 2008; Mor et al. 2009, hereafter M09).”
• BAT AGN Spectroscopic Survey. I. Spectral Measurements, Derived Quantities, and AGN Demographics (2017, background): “Dust is thought to be destroyed in the BLR, but to extend throughout the NLR (e.g., Mor et al. 2009).”
• Molecular line emission in NGC 1068 imaged with ALMA: I. An AGN-driven outflow in the dense molecular gas (2014, methodology): “More specifically, these models reproduce the non-stellar NIR and MIR SEDs and MIR spectroscopy of local Seyfert galaxies (Ramos Almeida et al. 2009, 2011a; Hoenig et al. 2010; Alonso-Herrero et al. 2011; Lira et al. 2013) and PG quasars (Mor et al. 2009).”
• Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, unknown): “2008; Mor et al. 2009).”
• TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY (2011, methodology): “The first one is the geometrical covering factor f2, which does not depend on the viewing angle, and is derived by integrating the AGN escape probability (Equation 3) over all angles as put forward by Mor et al. (2009).”
• ON THE UNIFICATION OF ACTIVE GALACTIC NUCLEI (2012, background): “…these earlier figures are afflicted by the computer bug reported in Nenkova et al. (2010). of AGNs, which were selected by different, unrelated criteria, does not constitute a complete sample (only the Mor et al. 2009 analysis of PG quasars involved a complete sample), it does illustrate the point.”
• OUTFLOWS FROM ACTIVE GALACTIC NUCLEI: KINEMATICS OF THE NARROW-LINE AND CORONAL-LINE REGIONS IN SEYFERT GALAXIES, (2011, background): “Recently, Mor et al. (2009) analyzed mid-IR spectra of AGNs using clumpy torus models and found that for a mean number of five clouds along any equatorial radial line (number of clouds varying between 1 and 10) there is a reasonable probability (>∼1”
• Smooth and clumpy dust distributions in AGN: a direct comparison of two commonly explored infrared emission models (2012, methodology): “The same models, however, fail to reproduce the short wavelength emission emerging from the hot dust (e.g. Mor et al. 2009) in type 1 AGN.”
• REVERBERATION MEASUREMENTS OF THE INNER RADIUS OF THE DUST TORUS IN 17 SEYFERT GALAXIES (2014, background): “…grains in the clouds (Netzer & Laor 1993), which were located between the reverberation radii of the K-band dust emission region and the Hβ BLR. Mor et al. (2009) reported near-infrared excess emission in the infrared SEDs of AGNs that could not be explained by the components of emission from…”
• DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, background): “Observational evidence strongly suggest that large graphite grains dominate this hot sublimation zone (e.g. Kishimoto et al. 2007, 2009b; Mor et al. 2009; Kishimoto et al. 2011a; Mor & Netzer 2012).”
• TESTING THE UNIFICATION MODEL FOR ACTIVE GALACTIC NUCLEI IN THE INFRARED: ARE THE OBSCURING TORI OF TYPE 1 AND 2 SEYFERTS DIFFERENT? (2011, methodology): “These models are making significant progress in accounting for the MIR emission of AGNs (Mason et al. 2006, 2009; Mor et al. 2009; Horst et al. 2008, 2009; Nikutta et al. 2009; Ramos Almeida et al. 2009a; Hönig et al. 2010).”
• The dust covering factor in active galactic nuclei (2016, methodology): “The origin of this excess is unclear and plausible sources include hot graphite dust (Mor et al. 2009) and low density inter-clump dust in the twophase torus model (Stalevski et al. 2012b,a).”