Research Notes of the AAS | 2021
The Distance of the Narrow FeKalpha Emitting Region for a Sample of Compton-thin Type-II Active Galactic Nuclei
Abstract
I have studied the variability of the FeKα emission line flux in response to changes in the 2–10\u2009keV unabsorbed flux in a sample of Compton thin type-II active galactic nuclei. All of the 20 sources in the sample studied by Laha et al., exhibit the presence of a narrow FeKα emission line. Except for one source (NGC\u20092992), all other sources show no correlations between the FeKα emission line flux and 2–10\u2009keV unabsorbed flux. This implies that although most of the sources have shown significant variations in their 2–10\u2009keV flux, the FeKα emission line did not get enough time to respond to those changes. This helps us put lower limits on the distance of the FeKα emitters to >10 lt-yr from the central engine, equivalent to ∼3\u2009pc which is consistent with the standard torus/narrow-line-region distance. I conclude that the FeKα emission lines of these sources arise from reflection of the hard X-ray photons off neutral materials located beyond \u2009pcscale.