Constraints on the nuclear emission of the Circinus galaxy: the torus

In the context of the unified model of Seyfert galaxies, we use observations from the literature and a radiative transfer model to investigate the near–IR to mm emission produced by the presumed torus in the Circinus galaxy, from 2μm to 1.3mm. From the infrared SED modelling, we find that the total luminosity (LIR) in this wavelength range, consists of similar contributions from the torus and starburst with a ratio of nuclear luminosity to starburst luminosity (LNUC/LSB) ∼ 0.8. By using a similar torus model to that of NGC1068, but without the conical dust, we find an upper limit to the outer torus radius of ∼12pc with a best fit of ∼2pc. The upper limit torus size estimated from the radiative transfer modelling is consistent with the 16pc torus radius estimated from near–IR imaging polarimetry of Circinus.