Differences in the dense gas between type 1 and type 2 Seyferts

We have used observations of the CO J = 1 --> 0 transition in a sample of 2 0 Seyfert galaxies in order to, test the result of Heckman et al. (1989), w ho find that type 2 Seyferts have a higher molecular gas content than type 1 Seyferts. From our observational results alone, we possibly find that L-C O/L-FIR (Sy2) approximate to L-CO/L-FIR (Sy1) for L-FIR similar to 10(11)L( circle dot) Seyferts, but L-CO/L-FIR (Sy2) approximate to 3L(CO)/L-FIR (Sy1 ), when we use all of our sample (L-FIR similar to 10(10) - 10(11)L(circle dot)). The results suggest that star-burst activity is most dominant in the (L-FIR similar to 10(10)L(circle dot)) type 2 Seyferts. and the relative c ontribution of this activity to the FIR flux (compared to the AGN) may decr ease with increasing L-FIR. Also, in order to test whether the Seyfert classes differ in their molecula r gas distributions, we have used a simple model to estimate the inclinatio n of the sub-kpc scale molecular ring, and, upon comparison with the observ ed spectra, conclude that the ring is generally aligned with the galactic d isc, with the largest deviations from this being exhibited by the type 1 Se yferts. With regard to the nucleus, for most of the sample, the pc-scale ob scuring torus appears to be approximately (within approximate to 30 degrees ) aligned with the molecular ring for both Seyfert classes.