It has been suggested that the narrow cores of the Fe K \alpha emission lines in Active Galactic Nuclei ( AGNs ) are likely produced in the torus , the inner radius of which can be measured by observing the lag time between the V and K band flux variations .
In this paper , we compare the virial products of the infrared time lags , and the narrow Fe K \alpha widths for 10 type 1 AGNs , with the black hole masses from other techniques .
We found the narrow Fe K \alpha line width is in average 2.6 ^ { +0.9 } _ { -0.4 } times broader than expected , assuming an isotropic velocity distribution of the torus at the distance measured by the infrared lags .
We propose the thick disk model of the torus may explain the observed larger line width .
Another possibility is the contamination by emission from the broad line region or the outer accretion disk .
Alternatively , the narrow iron line might originate from the inner most part of the obscuring torus within the sublimation radius , while the infrared emission may be from the outer cooler part .
We note the correlations between the black hole masses based on this new technique and those based on other known techniques are statistically insignificant .
We argue that this could be attributed to the small sample size and the very large uncertainties in the measurements of iron K line widths .
The next generation of X-ray observatories could help verify the origin of the narrow iron K \alpha line and the reliability of this new technique .