THE ORIENTATION OF THE NUCLEAR OBSCURER OF THE ACTIVE GALACTIC NUCLEI

We examine the distribution of axis ratios of a large sample of disk galaxies hosting type 2 active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey and compare it with a well-defined control sample of non-active galaxies. We find them significantly different, where the type 2 AGNs show both an excess of edge-on objects and deficit of round objects. This systematical bias cannot be explained by a nuclear obscurer oriented randomly with respect to the stellar disk. However, a nuclear obscurer coplanar with the stellar disk also does not fit the data very well. By assuming that the nuclear obscurer having an opening angle of similar to 60 degrees, we find that the observed axis ratio distribution can be nicely reproduced by a mean tilt angle of similar to 30 degrees between the nuclear obscurer and the stellar disk.