Observing Cool Dust Around Active Galactic Nuclei Using the SOFIA Telescope

Dust surrounding supermassive black holes (SMBHs) in active galactic nuclei (AGN) intercepts optical and UV radiation from the center and reradiates in midinfrared (MIR) wavelengths. Observed differences in AGN properties are largely explained by a toroidal distribution this surrounding dust, blocking direct view of the center in some lines of sight. Observations show that this dust lies in the central 1 – 10 pc from the SMBH.  Subarcsecond resolution photometric and spectroscopic data between 1 – 20 μm have been used to compute the nuclear spectral energy distributions (SEDs) of many AGN tori using ground-based telescopes. Although these previous studies have effectively described torus model parameters, the lack of high spatial resolution observations at longer wavelengths leaves the SED largely unconstrained. SOFIA observations of the central 0.1 – 1kpc (~3 – 4”) of the AGN in our sample are the highest resolution images available in this wavelength range. However, for AGN at distances on the order of tens of Mpc, SOFIA cannot resolve the parsec-scale torus structure, and contamination from diffuse IR emission and star formation (SF) can contaminate nuclear observations. Using observations from SOFIA’s Cycle 2 and Cycle 4, we add 30 – 40 μm photometric data to the IR SED of the torus models, and also identify the origin of diffuse extended emission.