1999A&A...344..767C

From previous work on the Circinus galaxy we postulated that ≃50% of the molecular gas in this type 2 Seyfert nucleus is distributed in a sub-kiloparsec circumnuclear ring, probably associated with the ongoing star-burst. In addition to this, we postulated the possible presence of a molecular outflow along the galaxy's minor axis. In this work we use a modified version of the routine used previously (Curran et al., 1998A&A...338..863C) in order to model this feature. From our results we believe that a 90° wide outflow, which constitutes ≃40% of the molecular gas within the central ±600pc, extends to a distance of ≃±500pc along the rotation axis of the ring with a maximum velocity of ≃190km/s. The bulk velocity, which is somewhat lower than this, gives an estimate of >10⁷L_☉ for the mechanical luminosity of the outflow. Armed with a model of the molecular gas distribution, and the fact that the large scale molecular ring appears to be perpendicular to the outflow/radio jets, we modelled how the CO luminosity varies with ring and outflow inclination i.e. Seyfert type. Our results show that in the case of a ring+outflow system, we expect very little difference in the luminosities of a face-on and an identical edge-on system. In the case of a ring only distribution however, we do expect, due to ``hole'' in the gas, slightly more emission from a sufficiently close edge-on system, but still not enough to account for the differences in CO luminosities which have been observed between type 1 and type 2 Seyferts. This result supports the notion that something more than mere orientation comes into play when explaining these differences, thus having major implications for the unified theories of active galactic nuclei.