WHERE IS THE CORONAL LINE REGION IN ACTIVE GALACTIC NUCLEI

We report the new finding that type 1 Seyfert nuclei (S1s) have excess [Fe VII] lambda 6087 emission with respect to type 2 Seyfert nuclei ( S2s). The S1s exhibit broad emission lines that are attributed to ioni zed gas within 1 pc of the black hole, whereas the S2s do not show suc h broad lines. The current unified model of active galactic nuclei exp lains this difference as follows: the central 1 pc region in the S2s i s hidden from the line of sight by a dusty torus if we observe it from a nearly edge-on view toward the torus. Therefore, our finding implie s that the coronal line region (CLR) traced by the [Fe VII] lambda 608 7 emission resides in the inner wall of such dusty tori. On the other hand, the frequency of occurrence of the CLR in the optical spectra is nearly the same between the S1s and the S2s. Moreover, some Seyfert n uclei exhibit a very extended (similar to 1 kpc) CLR. All these observ ational results can be unified if we introduce a three-component model for the CLR: (1) the inner wall of the dusty torus, (2) the clumpy io nized region associated with the narrow-line region at a distance from similar to 10 to similar to 100 pc, and (3) the extended ionized regi on at a distance similar to 1 kpc.