Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: revealing the inner funnel of dust

Raban, D.; Jaffe, W.; Röttgering, H. J. A.; Meisenheimer, K.; Tristram, K.

doi:10.1111/j.1365-2966.2009.14439.x

Cited by 209 publications

(306 citation statements)

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“…Through MIR interferometric observations, Jaffe et al (2004) estimated a warm (T = 320 K) dust structure with a 2.1 pc thick and 3.4 pc diameter, surrounding a hot (T > 800 K) compact (∼1 pc) structure. Additional MIR interferometric observation by Raban et al (2009) suggested a hot (∼800 K) 1.35 pc long and 0.45 pc thick structure with a larger 3 × 4 pc and warm (T ∼300 K) dust structure at a P.A. = −42 • .…”

Section: Analysis and Discussionmentioning

confidence: 93%

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

López-Rodríguez

Packham

Roche

et al. 2016

Mon. Not. R. Astron. Soc.

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We present sub-arcsecond 7.5−13 µm imaging-and spectro-polarimetric observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio CANARIAS. At all wavelengths, we find: (1) A 90 × 60 pc extended polarized feature in the northern ionization cone, with a uniform ∼44 • polarization angle. Its polarization arises from dust and gas emission in the ionization cone, heated by the active nucleus and jet, and further extinguished by aligned dust grains in the host galaxy. The polarization spectrum of the jet-molecular cloud interaction at ∼24 pc from the core is highly polarized, and does not show a silicate feature, suggesting that the dust grains are different from those in the interstellar medium. (2) A southern polarized feature at ∼9.6 pc from the core. Its polarization arises from a dust emission component extinguished by a large concentration of dust in the galaxy disc. We cannot distinguish between dust emission from magnetically aligned dust grains directly heated by the jet close to the core, and aligned dust grains in the dusty obscuring material surrounding the central engine. Silicate-like grains reproduce the polarized dust emission in this feature, suggesting different dust compositions in both ionization cones. (3) An upper limit of polarization degree of 0.3 per cent in the core. Based on our polarization model, the expected polarization of the obscuring dusty material is 0.1 per cent in the 8−13 µm wavelength range. This low polarization may be arising from the passage of radiation through aligned dust grains in the shielded edges of the clumps.

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Section: Analysis and Discussionmentioning

confidence: 93%

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

López-Rodríguez

Packham

Roche

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Swain et al (2003) presented K-band long-baseline A&A 523, A27 (2010) interferometry of the type-1 AGN NGC 4151, which arguably resolve the innermost hot region of the dust torus (see Kishimoto et al 2007, for this interpretation). More recently, VLTI/MIDI long-baseline mid-IR spectro-interferometry directly revealed the parsec-scaled dust emission sizes in the wavelength band from 8 to 13 μm for a number of nearby type 1 and type 2 AGN (Jaffe et al 2004;Tristram et al 2007;Beckert et al 2008;Raban et al 2009;Tristram et al 2009). These observations finally confirmed the basic picture of the dust torus, while more detailed characteristics remain unclear.…”

Section: Introductionmentioning

confidence: 99%

The dusty heart of nearby active galaxies

Hönig

Kishimoto

2010

A&A

200

221

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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 τ V ∼ 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.

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“…Reflection is associated with the reprocessing of the primary continuum by material either close to the central black hole, in the accretion disk (George & Fabian 1991;Matt et al 1991), or more distant, for example in a torus (Antonucci 1993;Jaffe et al 2004;Meisenheimer et al 2007;Raban et al 2009). A&A 567, A44 (2014) It can also be produced either in the narrow-or broad-line regions .…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength campaign on Mrk 509

Boissay

Paltani

Ponti

et al. 2014

A&A

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Active galactic nuclei (AGN) are the most luminous persistent objects in the universe. The X-ray domain is particularly important because the X-ray flux represents a significant fraction of the bolometric emission from such objects and probes the innermost regions of accretion disks, where most of this power is generated. An excess of X-ray emission below ∼2 keV, called soft-excess, is very common in Type 1 AGN spectra. The origin of this feature remains debated. Originally modeled with a blackbody, there are now several possibilities to model the soft-excess, including warm Comptonization and blurred ionized reflection. In this paper, we test ionized-reflection models on Mrk 509, a bright Seyfert 1 galaxy for which we have a unique data set, in order to determine whether it can be responsible for the strong soft-excess. We use ten simultaneous XMM-Newton and INTEGRAL observations performed every four days. We present here the results of the spectral analysis, the evolution of the parameters, and the variability properties of the X-ray emission. The application of blurred ionized-reflection models leads to a very strong reflection and an extreme geometry, but fails to reproduce the broad-band spectrum of Mrk 509. Two different scenarios for blurred ionized reflection are discussed: stable geometry and lamp-post configuration. In both cases we find that the model parameters do not follow the expected relations, indicating that the model is fine-tuned to fit the data without physical justification. A large, slow variation in the soft-excess without a counterpart in the hard X-rays could be explained by a change in ionization of the reflector. However, such a change does not naturally follow from the assumed geometrical configuration. Warm Comptonization remains the most probable origin of the soft-excess in this object. Nevertheless, it is possible that both ionized reflection and warm Comptonization mechanisms can explain the soft-excess in all objects, one dominating the other one, depending on the physical conditions of the disk and the corona.

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Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: revealing the inner funnel of dust

Cited by 209 publications

References 50 publications

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

The dusty heart of nearby active galaxies

Multiwavelength campaign on Mrk 509

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