Investigating the dusty torus of Seyfert galaxies using SOFIA/FORCAST photometry

Fuller, L., López Rodríguez, E., Packham, C., Ramos Almeida, C., Alonso Herrero, A., Levenson, N. A., Rdomski, J., Ichikawa, K., García Bernete, I., González Martín, O., Díaz Santos, T., Martínez Paredes, M. 2016. Investigating the dusty torus of Seyfert galaxies using SOFIA/FORCAST photometry. Monthly Notices of the Royal Astronomical Society 462, 3, 2618-2630 DOI: 10.1093/mnras/stw1780

We present 31.5 mu m imaging photometry of 11 nearby Seyfert galaxies observed from the Stratospheric Observatory For Infrared Astronomy (SOFIA) using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We tentatively detect extended 31 mu m emission for the first time in our sample. In combination with this new data set, subarcsecond resolution 1-18 mu m imaging and 7.5-13 mu m spectroscopic observations were used to compute the nuclear spectral energy distribution (SED) of each galaxy. We found that the turnover of the torus emission does not occur at wavelengths <= 31.5 mu m, which we interpret as a lower-limit for the wavelength of peak emission. We used CLUMPY torus models to fit the nuclear infrared (IR) SED and infer trends in the physical parameters of the AGN torus for the galaxies in the sample. Including the 31.5 mu m nuclear flux in the SED (1) reduces the number of clumpy torus models compatible with the data, and (2) modifies the model output for the outer radial extent of the torus for 10 of the 11 objects. Specifically, six (60 per cent) objects show a decrease in radial extent while four (40 per cent) show an increase. We find torus outer radii ranging from <1 to 8.4 pc.

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