The Emission and Distribution of Dust of the Torus of NGC 1068

Enrique Lopez-Rodriguez, Lindsay Fuller, Almudena Alonso-Herrero, Andreas Efstathiou, Kohei Ichikawa, Nancy A. Levenson, Chris Packham, James Radomski, Cristina Ramos Almeida, Dominic J. Benford, Marc Berthoud, Ryan Hamilton, Doyal Harper, Attila Kovavcs, Fabio P. Santos, J. Staguhn, Terry Herter. 2018. The Emission and Distribution of Dust of the Torus of NGC 1068. Astrophysical Journal 859, 2, DOI: 10.3847/1538-4357/aabd7b

We present observations of NGC 1068 covering the 19.7-53.0 mu m wavelength range using FORCAST and HAWC+ on board SOFIA. Using these observations, high-angular-resolution infrared (IR) and submillimeter observations, we find an observational turnover of the torus emission in the 30-40 mu m wavelength range with a characteristic temperature of 70-100 K. This component is clearly different from the diffuse extended emission in the narrow line and star formation regions at 10-100 mu m within the central 700 pc. We compute 2.2-432 mu m 2D images using the best inferred CLUMPY torus model based on several nuclear spectral energy distribution (SED) coverages. We find that when 1-20 mu m SED is used, the inferred result gives a small torus size (<4 pc radius) and a steep radial dust distribution. The computed torus using the 1-432 mu m SED provides comparable torus sizes, 5.1(-0.4)(+0.4) pc radius, and morphology to the recently resolved 432 mu m Atacama Large Millimeter Array observations. This result indicates that the 1-20 mu m wavelength range is not able to probe the full extent of the torus. The characterization of the turnover emission of the torus using the 30-60 mu m wavelength range is sensitive to the detection of cold dust in the torus. The morphology of the dust emission in our 2D image at 432 mu m is spatially coincident with the cloud distribution, while the morphology of the emission in the 1-20 mu m wavelength range shows an elongated morphology perpendicular to the cloud distribution. We find that our 2D CLUMPY torus image at 12 mu m can produce comparable results to those observed using IR interferometry.

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