We present spectroscopic observations of the type 2 quasar SDSS J11311.05+162739.5 ( Q1131+16 hereafter ; z=0.1732 ) , which has the richest spectrum of forbidden high ionisation lines ( FHIL , e.g .
[ Fe vii ] , [ Fe x ] , [ Fe xi ] and [ Ne v ] ) yet reported for an AGN , as well as unusually strong [ O iii ] \lambda 4363 emission .
The study of this object provides a rare opportunity to investigate the physical conditions and kinematics of the region ( s ) emitting the FHILs .
By comparison with photoionisation model results , we find that the FHIL region has high densities ( 10 ^ { 5.5 } < n _ { H } < 10 ^ { 8.0 } cm -3 ) and ionisation parameters ( -1.5 < log [ U ] < 0 ) , yet its kinematics are similar to those of the low ionisation emission line region detected in the same object ( FWHM \sim 360 \pm 30 km/s ) , with no evidence for a significant shift between the velocity centroid of the FHILs and the rest frame of the host galaxy .
The deduced physical conditions lie between those of the Broad-Line ( n _ { H } > 10 ^ { 9 } cm -3 ) and Narrow-Line Regions ( n _ { H } < 10 ^ { 6 } cm -3 ) of active galactic nuclei ( AGN ) , and we demonstrate that the FHIL regions must be situated relatively close to the illuminating AGN ( 0.32 < r _ { FHIL } < 50pc ) .
We suggest that the inner torus wall is the most likely location for the FHIL region , and that the unusual strength of the FHILs in this object is due to a specific viewing angle of the far wall of the torus , coupled with a lack of dust on larger scales that might otherwise obscure our view of the torus .