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

By D. Raban, W. Jaffe, H. Rottgering, K. Meisenheimer, K. Tristram. 2009

172 citations recorded by the source corpus.

We present new interferometric data obtained with MIDI (MID infrared Interferometric instrument) for the Seyfert II galaxy NGC 1068, with an extensive coverage of sixteen uv points. These observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, suffi cient uv points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to tho se obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner f unnel of the obscuring torus, is hot (∼800K), 1.35 parsec long, and 0.45 parsec thick in FWHM at a PA=−42 ◦ (from north to east). It has an absorption profile di fferent than standard interstellar dust and with evidence for clumpiness. The second component is 3× 4 pc in FWHM with T=∼300K, and we identify it with the cooler body of the torus. The compact component is tilted by∼ 45 ◦ with respect to the radio jet and has similar size and orientation to the obse rved water maser distribution. We show how the dust distribution relates to other observables within a few parsecs of the core of the galaxy such as the nuclear masers, the radio jet, and the i onization cone. We compare our findings to a similar study of the Circinus galaxy and other re levant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c50bc0129c9ff56a60304d00861cd3daab25fc66

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In Astronomy and Astrophysics

1. H. Netzer
2. D. M. Alexander
3. R. Hickox
4. M. Kishimoto
5. L. Hernquist
6. P. Hopkins
7. S. Hönig
8. V. Wakelam

In Instrumentation

1. D. M. Alexander
2. R. Hickox
3. J. Fritz
4. M. Stalevski
5. Maarten Baes
6. Wolfgang J. Duschl
7. D. Asmus
8. L. Tacconi

Citations in the corpus

• Adaptive Optics for Astronomy (2012, background): “…the torus may be a dynamically evolving structure with different components responsible for the various observed phenomena, including small scales structures seen with VLTI (Burtscher et al. 2009, 2010, Raban et al. 2009, Tristram et al. 2007) as well as larger scale components (Hicks et al. 2009).”
• The dusty heart of nearby active galaxies. II. From clumpy torus models to physical properties of dust around active galactic nuclei (2009, background): “…used for a number of nearby objects (Swain et al. 2003; Wittkowski et al. 2004; Weigelt et al. 2004; Jaffe et al. 2004; Poncelet et al. 2006; Meisenheimer et al. 2007; Tristram et al. 2007; Beckert et al. 2008; Raban et al. 2009; Tristram et al. 2009; Burtscher et al. 2009; Kishimoto et al. 2009b).”
• TESTING THE UNIFICATION MODEL FOR ACTIVE GALACTIC NUCLEI IN THE INFRARED: ARE THE OBSCURING TORI OF TYPE 1 AND 2 SEYFERTS DIFFERENT? (2011, background): “…in our sample have outer radii smaller than 6 pc (Ta- bles 11 and B3), in agreement with MIR direct imaging of nearby Seyferts (Packham et al. 2005; Radomski et al. 2008) and also interferometric observations (Jaffe et al. 2004; Tristram et al. 2007; Meisenheimer et al. 2007; Raban et al. 2009).”
• What drives the growth of black holes (2011, background): “These size scales correspond to that expected for (and in some cases observed; e.g., Tristram et al. 2007, 2009; Raban et al. 2009; Kishimoto et al. 2011), the dusty molecular torus that is thought to obscure the central regions of the AGN in inclined systems (e.g., as postulated in the unified AGN…”
• DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARED EMISSION OF ACTIVE GALACTIC NUCLEI (2013, background): “Similar trends have been found in other AGN on similar spatial scales (NGC 1068, Circinus, and NGC424; Raban et al. 2009; Tristram et al. 2012; Hönig et al. 2012) and may be explained by contribution from a hot-dust component at the shorter wavelength end that has a different orientation (see Sect.”
• TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY (2011, methodology): “…point of view, mid-IR interferometric observations have revealed that the torus is relatively compact, with typical sizes of a few parsecs, geometrically thick, and with evidence of clumpiness (e.g., Jaffe et al. 2004; Tristram et al. 2007, 2009; Burtscher et al. 2009; Raban et al. 2009).”
• A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies (2013, background): “For the other sources with known asymmetry in the nuclear dust component, a strong signal is also evident in these plots, i.e. NGC 1068 (Raban et al., 2009), the Circinus galaxy (Tristram et al., 2012) and NGC 424 (Hönig et al., 2012).”
• A NEW NETWORK FOR HIGHER-TEMPERATURE GAS-PHASE CHEMISTRY. I. A PRELIMINARY STUDY OF ACCRETION DISKS IN ACTIVE GALACTIC NUCLEI (2010, methodology): “…NGC 1068 was actually obtained by fitting a clumpy model to observational data on the dusty torus in NGC 1068 (Mason et al. 2006; Nenkova et al. 2008), which shows the dust temperature to be 800 K in the inner sub-pc torus and 300 K for the few-pc-sized torus (Jaffe et al. 2004; Raban et al. 2009).”
• First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN (2014, background): “Recent IR interferometric observations indeed do affirm such a co-existence of hot (800 K) and cooler (∼ 200 − 300 K) dust components in nearby AGN (Jaffe et al. 2004; Poncelet et al. 2006; Tristram et al. 2007; Raban et al. 2009).”
• Molecular line emission in NGC 1068 imaged with ALMA: I. An AGN-driven outflow in the dense molecular gas (2014, background): “…luminosity of the AGN in NGC 1068 (Lbol), estimated from MIR and Xray wavelengths, is at least three orders of magnitude larger than Lkin: Lbol ≥ 1044−45erg s−1 (Bock et al. 2000; Laurent et al. 2000; Matt et al. 2000; Raban et al. 2009; Prieto et al. 2010; AlonsoHerrero et al. 2011 and Sect.”
• The dust covering factor in active galactic nuclei (2016, background): “Finally, Raban et al. (2009) conclude that the current phase of the AGN in NGC 1068 is not likely to have significant effect on the black hole spin (and thus the orientation of the jet), and that it is the angular momentum of the infalling material together with the gravitational potential of the…”
• The dusty torus in the Circinus galaxy: a dense disk and the torus funnel (2013, background): “Two clearly separated emission components have also been found in NGC 1068 and NGC 3783 (Raban et al. 2009; Hönig et al. 2013), and a two-component morphology in the infrared appears to be common to a large number of AGN (Kishimoto et al. 2011b; Burtscher et al. 2013).”